Sex differences in response to visual sexual stimuli: a review.
Rupp Heather A,Wallen Kim
Archives of sexual behavior
This article reviews what is currently known about how men and women respond to the presentation of visual sexual stimuli. While the assumption that men respond more to visual sexual stimuli is generally empirically supported, previous reports of sex differences are confounded by the variable content of the stimuli presented and measurement techniques. We propose that the cognitive processing stage of responding to sexual stimuli is the first stage in which sex differences occur. The divergence between men and women is proposed to occur at this time, reflected in differences in neural activation, and contribute to previously reported sex differences in downstream peripheral physiological responses and subjective reports of sexual arousal. Additionally, this review discusses factors that may contribute to the variability in sex differences observed in response to visual sexual stimuli. Factors include participant variables, such as hormonal state and socialized sexual attitudes, as well as variables specific to the content presented in the stimuli. Based on the literature reviewed, we conclude that content characteristics may differentially produce higher levels of sexual arousal in men and women. Specifically, men appear more influenced by the sex of the actors depicted in the stimuli while women's response may differ with the context presented. Sexual motivation, perceived gender role expectations, and sexual attitudes are possible influences. These differences are of practical importance to future research on sexual arousal that aims to use experimental stimuli comparably appealing to men and women and also for general understanding of cognitive sex differences.
The role of anterior and posterior insula in male genital response and in visual attention: an exploratory multimodal fMRI study.
Cera Nicoletta,Castelhano João,Oliveira Cátia,Carvalho Joana,Quinta Gomes Ana Luísa,Peixoto Maria Manuela,Pereira Raquel,Janssen Erick,Castelo-Branco Miguel,Nobre Pedro
Several studies highlighted the role of insula on several functions and in sexual behavior. This exploratory study examines the relationships among genital responses, brain responses, and eye movements, to disentangle the role played by the anterior and posterior insula during different stages of male sexual response and during visual attention to sexual stimuli. In 19 healthy men, fMRI, eye movement, and penile tumescence data were collected during a visual sexual stimulation task. After a whole-brain analysis comparing neutral and sexual clips and confirming a role for the bilateral insulae, we selected two bilateral seed regions in anterior and posterior insula for functional connectivity analysis. Single-ROI-GLMs were run for the FC target regions. Single-ROI-GLMs were performed based on areas to which participants fixate: "Faces", "Genitals," and "Background" with the contrast "Genitals > Faces". Single-ROI-GLMs with baseline, onset, and sustained PT response for the sexual clips were performed. We found stronger effects for the posterior than the anterior insula. In the target regions of the posterior insula, we found three different pathways: the first involved in visual attention, onset of erection, and sustained erection; the second involved only in the onset of erection, and the third limited to sustained erection.
Sex differences in main olfactory system pathways involved in psychosexual function.
Cherry James A,Baum Michael J
Genes, brain, and behavior
We summarize literature from animal and human studies assessing sex differences in the ability of the main olfactory system to detect and process sex-specific olfactory signals ("pheromones") that control the expression of psychosexual functions in males and females. A case is made in non primate mammals for an obligatory role of pheromonal signaling via the main olfactory system (in addition to the vomeronasal-accessory olfactory system) in mate recognition and sexual arousal, with male-specific as well as female-specific pheromones subserving these functions in the opposite sex. Although the case for an obligatory role of pheromones in mate recognition and mating among old world primates, including humans, is weaker, we review the current literature assessing the role of putative human pheromones (eg, AND, EST, "copulin"), detected by the main olfactory system, in promoting mate choice and mating in men and women. Based on animal studies, we hypothesize that sexually dimorphic effects of putative human pheromones are mediated via main olfactory inputs to the medial amygdala which, in turn, transmits olfactory information to sites in the hypothalamus that regulate reproduction.
The sensory cortical representation of the human penis: revisiting somatotopy in the male homunculus.
Kell Christian A,von Kriegstein Katharina,Rösler Alexander,Kleinschmidt Andreas,Laufs Helmut
The Journal of neuroscience : the official journal of the Society for Neuroscience
Pioneering mapping studies of the human cortex have established the notion of somatotopy in sensory representation, which transpired into Penfield and Rasmussen's famous sensory homunculus diagram. However, regarding the primary cortical representation of the genitals, classical and modern findings appear to be at odds with the principle of somatotopy, often assigning it to the cortex on the mesial wall. Using functional neuroimaging, we established a mediolateral sequence of somatosensory foot, penis, and lower abdominal wall representation on the contralateral postcentral gyrus in primary sensory cortex and a bilateral secondary somatosensory representation in the parietal operculum.
Neuroimaging and sexual behavior: identification of regional and functional differences.
Cheng Joseph C,Secondary Joseph,Burke William H,Fedoroff J Paul,Dwyer R Gregg
Current psychiatry reports
The neuroanatomical correlates of human sexual desire, arousal, and behavior have been characterized in recent years with functional brain imaging techniques such as magnetic resonance imaging (MRI) and positron emission tomography (PET). Here, we briefly review the results of functional neuroimaging studies in humans, whether healthy or suffering from sexual disorders, and the current models of regional and network activation in sexual arousal. Attention is paid, in particular, to findings from both regional and network studies in the past 3 years. We also identify yet unanswered and pressing questions of interest to areas of ongoing investigations for psychiatric, scientific, and forensic disciplines.
Film excerpts shown to specifically elicit various affects lead to overlapping activation foci in a large set of symmetrical brain regions in males.
Karama Sherif,Armony Jorge,Beauregard Mario
While the limbic system theory continues to be part of common scientific parlance, its validity has been questioned on multiple grounds. Nonetheless, the issue of whether or not there exists a set of brain areas preferentially dedicated to emotional processing remains central within affective neuroscience. Recently, a widespread neural reference space for emotion which includes limbic as well as other regions was characterized in a large meta-analysis. As methodologically heterogeneous studies go into such meta-analyses, showing in an individual study in which all parameters are kept constant, the involvement of overlapping areas for various emotion conditions in keeping with the neural reference space for emotion, would serve as valuable confirmatory evidence. Here, using fMRI, 20 young adult men were scanned while viewing validated neutral and effective emotion-eliciting short film excerpts shown to quickly and specifically elicit disgust, amusement, or sexual arousal. Each emotion-specific run included, in random order, multiple neutral and emotion condition blocks. A stringent conjunction analysis revealed a large overlap across emotion conditions that fit remarkably well with the neural reference space for emotion. This overlap included symmetrical bilateral activation of the medial prefrontal cortex, the anterior cingulate, the temporo-occipital junction, the basal ganglia, the brainstem, the amygdala, the hippocampus, the thalamus, the subthalamic nucleus, the posterior hypothalamus, the cerebellum, as well as the frontal operculum extending towards the anterior insula. This study clearly confirms for the visual modality, that processing emotional stimuli leads to widespread increases in activation that cluster within relatively confined areas, regardless of valence.
Brain activation by visual erotic stimuli in healthy middle aged males.
Kim S W,Sohn D W,Cho Y-H,Yang W S,Lee K-U,Juh R,Ahn K-J,Chung Y-A,Han S-I,Lee K H,Lee C U,Chae J-H
International journal of impotence research
The objective of the present study was to identify brain centers, whose activity changes are related to erotic visual stimuli in healthy, heterosexual, middle aged males. Ten heterosexual, right-handed males with normal sexual function were entered into the present study (mean age 52 years, range 46-55). All potential subjects were screened over 1 h interview, and were encouraged to fill out questionnaires including the Brief Male Sexual Function Inventory. All subjects with a history of sexual arousal disorder or erectile dysfunction were excluded. We performed functional brain magnetic resonance imaging (fMRI) in male volunteers when an alternatively combined erotic and nonerotic film was played for 14 min and 9 s. The major areas of activation associated with sexual arousal to visual stimuli were occipitotemporal area, anterior cingulate gyrus, insula, orbitofrontal cortex, caudate nucleus. However, hypothalamus and thalamus were not activated. We suggest that the nonactivation of hypothalamus and thalamus in middle aged males may be responsible for the lesser physiological arousal in response to the erotic visual stimuli.
Brain areas activated after ejaculation in healthy young human subjects.
Mallick H N,Tandon S,Jagannathan N R,Gulia K K,Kumar V M
Indian journal of physiology and pharmacology
Brain mechanisms for the refractory period that characteristically follows ejaculation in animals and human are poorly understood. The possibility of active inhibition of brain areas being responsible for the post-ejaculatory inhibitory state has not been ruled out. Using Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) we have mapped brain areas in healthy young volunteers immediately after ejaculation. Functional imaging of the brain for 30 minutes beginning after three minutes of ejaculation induced by masturbation showed spatio-temporal activation in amygdala, temporal lobes and septal areas. The septal areas were observed to be active for a shorter duration than the amygdala and the temporal lobe. Thus the temporal sequence of involvement of the above neural structures may contribute to temporary inhibition of sexual arousal/penile erection during the post-ejaculatory refractory period in humans.
A new potential of blood oxygenation level dependent (BOLD) functional MRI for evaluating cerebral centers of penile erection.
Park K,Seo J J,Kang H K,Ryu S B,Kim H J,Jeong G W
International journal of impotence research
It is well known that penile erection is dependent on commands from the central nervous system. However, there has been little research on the central control of penile erection. The aim of this study was to evaluate, for the first time, the cerebral centers of penile erection using BOLD-functional MRI. Functional magnetic resonance imaging (fMRI) on a 1.5T MR scanner was performed in 12 sexually potent male volunteers (mean age: 23) and two hypogonadal impotent patients. In this study, blood oxygenation level dependent (BOLD) technique was utilized to create fMRI reflecting local brain activities. Real-time visual stimulation was performed with an alternatively combined erotic and non-erotic film to identify and quantify the activated brain regions associated with sexual response. Subjective sexual arousal and penile erection responses were assessed using 5-point scales ranging from 1 (no change) to 5 (maximal increase). In normal volunteers, the mean scores on subjective sexual arousal and penile erection by sexual stimulation with erotic film were 3.0 and 3.3 respectively, whereas there were no changes by non-erotic stimulation. During the visual stimulation the occipital cortex was activated by either an erotic or non-erotic film, the erotic film gave 150-200% stronger activation. However, more than seven of the 12 healthy subjects were significantly activated in the areas of inferior frontal lobe, cingulate gyrus, insula gyrus, corpus callosum, thalamus, caudate nucleus, globus pallidus, and inferior temporal lobe by erotic stimulation. In the hypogonadal patients, brain activation in response to the erotic film decreased compared to normal volunteers, however, it was restored by testosterone supplementation. These results are the first demonstration to show the functional neuroanatomy of the brain associated with sexual arousal by visual sexual stimulation using BOLD-based fMRI. Further studies are needed to verify that fMRI provides an important new tool in evaluating the cerebral center of the penile erection.
Areas of brain activation in males and females during viewing of erotic film excerpts.
Karama Sherif,Lecours André Roch,Leroux Jean-Maxime,Bourgouin Pierre,Beaudoin Gilles,Joubert Sven,Beauregard Mario
Human brain mapping
Various lines of evidence indicate that men generally experience greater sexual arousal (SA) to erotic stimuli than women. Yet, little is known regarding the neurobiological processes underlying such a gender difference. To investigate this issue, functional magnetic resonance imaging was used to compare the neural correlates of SA in 20 male and 20 female subjects. Brain activity was measured while male and female subjects were viewing erotic film excerpts. Results showed that the level of perceived SA was significantly higher in male than in female subjects. When compared to viewing emotionally neutral film excerpts, viewing erotic film excerpts was associated, for both genders, with bilateral blood oxygen level dependent (BOLD) signal increases in the anterior cingulate, medial prefrontal, orbitofrontal, insular, and occipitotemporal cortices, as well as in the amygdala and the ventral striatum. Only for the group of male subjects was there evidence of a significant activation of the thalamus and hypothalamus, a sexually dimorphic area of the brain known to play a pivotal role in physiological arousal and sexual behavior. When directly compared between genders, hypothalamic activation was found to be significantly greater in male subjects. Furthermore, for male subjects only, the magnitude of hypothalamic activation was positively correlated with reported levels of SA. These findings reveal the existence of similarities and dissimilarities in the way the brain of both genders responds to erotic stimuli. They further suggest that the greater SA generally experienced by men, when viewing erotica, may be related to the functional gender difference found here with respect to the hypothalamus.
Romantic love: an fMRI study of a neural mechanism for mate choice.
Fisher Helen,Aron Arthur,Brown Lucy L
The Journal of comparative neurology
Scientists have described myriad traits in mammalian and avian species that evolved to attract mates. But the brain mechanisms by which conspecifics become attracted to these traits is largely unknown. Yet mammals and birds express mate preferences and make mate choices, and data suggest that this "attraction system" is associated with the dopaminergic reward system. It has been proposed that intense romantic love, a cross-cultural universal, is a developed form of this attraction system. To determine the neural mechanisms associated with romantic love we used functional magnetic resonance imaging (fMRI) and studied 17 people who were intensely "in love" (Aron et al.  J Neurophysiol 94:327-337). Activation specific to the beloved occurred in the right ventral tegmental area and right caudate nucleus, dopamine-rich areas associated with mammalian reward and motivation. These and other results suggest that dopaminergic reward pathways contribute to the "general arousal" component of romantic love; romantic love is primarily a motivation system, rather than an emotion; this drive is distinct from the sex drive; romantic love changes across time; and romantic love shares biobehavioral similarities with mammalian attraction. We propose that this attraction mechanism evolved to enable individuals to focus their mating energy on specific others, thereby conserving energy and facilitating mate choice-a primary aspect of reproduction. Last, the corticostriate system, with its potential for combining diverse cortical information with reward signals, is an excellent anatomical substrate for the complex factors contributing to romantic love and mate choice.
Men and women differ in amygdala response to visual sexual stimuli.
Hamann Stephan,Herman Rebecca A,Nolan Carla L,Wallen Kim
Men are generally more interested in and responsive to visual sexually arousing stimuli than are women. Here we used functional magnetic resonance imaging (fMRI) to show that the amygdala and hypothalamus are more strongly activated in men than in women when viewing identical sexual stimuli. This was true even when women reported greater arousal. Sex differences were specific to the sexual nature of the stimuli, were restricted primarily to limbic regions, and were larger in the left amygdala than the right amygdala. Men and women showed similar activation patterns across multiple brain regions, including ventral striatal regions involved in reward. Our findings indicate that the amygdala mediates sex differences in responsiveness to appetitive and biologically salient stimuli; the human amygdala may also mediate the reportedly greater role of visual stimuli in male sexual behavior, paralleling prior animal findings.
Magnetic resonance imaging of male and female genitals during coitus and female sexual arousal.
Schultz W W,van Andel P,Sabelis I,Mooyaart E
BMJ (Clinical research ed.)
OBJECTIVE:To find out whether taking images of the male and female genitals during coitus is feasible and to find out whether former and current ideas about the anatomy during sexual intercourse and during female sexual arousal are based on assumptions or on facts. DESIGN:Observational study. SETTING:University hospital in the Netherlands. METHODS:Magnetic resonance imaging was used to study the female sexual response and the male and female genitals during coitus. Thirteen experiments were performed with eight couples and three single women. RESULTS:The images obtained showed that during intercourse in the "missionary position" the penis has the shape of a boomerang and 1/3 of its length consists of the root of the penis. During female sexual arousal without intercourse the uterus was raised and the anterior vaginal wall lengthened. The size of the uterus did not increase during sexual arousal. CONCLUSION:Taking magnetic resonance images of the male and female genitals during coitus is feasible and contributes to understanding of anatomy.
Specific cerebral activation due to visual erotic stimuli in male-to-female transsexuals compared with male and female controls: an fMRI study.
Gizewski Elke R,Krause Eva,Schlamann Marc,Happich Friederike,Ladd Mark E,Forsting Michael,Senf Wolfgang
The journal of sexual medicine
INTRODUCTION:Transsexuals harbor the strong feeling of having been born to the wrong sex. There is a continuing controversial discussion of whether or not transsexualism has a biological representation. Differences between males and females in terms of functional imaging during erotic stimuli have been previously described, revealing gender-specific results. AIM:Therefore, we postulated that male-to-female (MTF) transsexuals may show specific cerebral activation differing from their biological gender. MAIN OUTCOME MEASURE:Cerebral activation patterns during viewing of erotic film excerpts in functional magnetic resonance imaging (fMRI). METHODS:Twelve male and 12 female heterosexual volunteers and 12 MTF transsexuals before any treatment viewed erotic film excerpts during fMRI. Additionally, subjective rating of sexual arousal was assessed. Statistics were performed using the Statistical Parametric Mapping software. RESULTS:Significantly enhanced activation for men compared with women was revealed in brain areas involved in erotic processing, i.e., the thalamus, the amygdala, and the orbitofrontal and insular cortex, whereas no specific activation for women was found. When comparing MTF transsexuals with male volunteers, activation patterns similar to female volunteers being compared with male volunteers were revealed. Sexual arousal was assessed using standard rating scales and did not differ significantly for the three groups. CONCLUSIONS:We revealed a cerebral activation pattern in MTF transsexuals compared with male controls similar to female controls compared with male controls during viewing of erotic stimuli, indicating a tendency of female-like cerebral processing in transsexualism.
[Identifying distinct components in the cerebral treatment of visual sexual information through functional neuroimaging].
Journal de la Societe de biologie
For now several years, the growing developement of neuroimaging techniques such as Positron Emission Tomography (PET) or functional Magnetic Resonance Imaging (fMRI) allowed a better understanding of neural processes involved in human emotions and goal-directed behaviors. In particular, several studies are now available on the neural correlates of male sexual arousal. A neurobehavioral model of neural processes involved in sexual arousal has been proposed (Redouté et al., 2000) comprising: i) a cognitive component; ii) an emotional component; iii) a motivational component and iv) an autonomic component. Among other regions, several cerebral areas have been found to be linked to: 1) the cognitive component which comprises: i) the orbitofrontal cortex involved in attentional processes directed toward the target and the superior parietal lobules; ii) the inferior parietal lobules involved in motor imagery processes; 2) the motivational component which involves the caudal part of the anterior cingulate cortex, related to motor preparation processes; 3) the autonomic component: concurrent measures of cerebral activations by functional neuroimaging and of erectile response by penile plethysmography allow the demonstration of the involvement of the hypothalamus, the insula, and the rostral part of the anterior cingulate cortex in this component.
Neuroimaging of sexual arousal: research and clinical utility.
Sumich A L,Kumari V,Sharma T
Hospital medicine (London, England : 1998)
The treatment of sexual dysfunction or deviancy requires an understanding of the underlying neural substrates. Neuroimaging techniques offer insight into brain regions involved in sexual arousal and inhibition. The development of robust paradigms has implications for the assessment and treatment of sexual disorder in men and women.
Brain activation areas of sexual arousal with olfactory stimulation in men: a preliminary study using functional MRI.
Huh Joon,Park Kwangsung,Hwang In Sang,Jung Seung Il,Kim Hyeong-Jung,Chung Tae-Woong,Jeong Gwang-Woo
The journal of sexual medicine
INTRODUCTION:There have been extensive studies evaluating the functional neuroanatomy of the brain during visual sexual stimulation. However, little data exist concerning the role of olfactory stimulation in human sexuality. AIM:This preliminary study intended to elucidate the brain areas responding to an olfactory sexual stimulus using functional magnetic resonance imaging (fMRI). METHODS:Eight healthy right-handed heterosexual male volunteers (20-35 years of age), having normal olfaction and no brain diseases, were recruited. During fMRI, a women's perfume was given as an olfactory sexual stimulant in an alternating block design with a 30-second stimulation period followed by a 30-second rest. After the fMRI sessions, the participants provided ratings for both the odorant's intensity and perceived arousal. MAIN OUTCOME MEASURES:The study subjects rated the odorant stimulation and perceived sexual arousal response by Likert-type rating scales. Brain activation maps were made by blood oxygenation level-dependent (BOLD)-based fMRI with an echo-planar imaging pulse sequence. RESULTS:Two out of eight subjects experienced "strong" sexual arousal, and three subjects experienced "moderate" arousal during olfactory stimulation, resulting in a mean score of 2.25 on a 4-point scale. The common brain areas activated in response to the odor stimulus in all eight subjects included the insula, the inferior and middle frontal gyrus, and the hypothalamus. The median cingulate gyrus, thalamus, angular gyrus, lingual gyrus, and cerebellar cortex were activated in subjects who had moderate or strong sexual arousal response. CONCLUSION:Olfactory stimulation with women's perfume produces the activation of specific brain areas in men. The brain areas activated differed according to the degree of perceived sexual arousal response. Further studies are needed to elucidate brain activation response according to the different kinds and intensities of olfactory stimulation.
Brain response to visual sexual stimuli in heterosexual and homosexual males.
Paul Thomas,Schiffer Boris,Zwarg Thomas,Krüger Tillmann H C,Karama Sherif,Schedlowski Manfred,Forsting Michael,Gizewski Elke R
Human brain mapping
Although heterosexual and homosexual individuals clearly show differences in subjective response to heterosexual and homosexual sexual stimuli, the neurobiological processes underlying sexual orientation are largely unknown. We addressed the question whether the expected differences in subjective response to visual heterosexual and homosexual stimuli may be reflected in differences in brain activation pattern. Twenty-four healthy male volunteers, 12 heterosexuals and 12 homosexuals, were included in the study. BOLD signal was measured while subjects were viewing erotic videos of heterosexual and homosexual content. SPM02 was used for data analysis. Individual sexual arousal was assessed by subjective rating. As compared to viewing sexually neutral videos, viewing erotic videos led to a brain activation pattern characteristic for sexual arousal in both groups only when subjects were viewing videos of their respective sexual orientation. Particularly, activation in the hypothalamus, a key brain area in sexual function, was correlated with sexual arousal. Conversely, when viewing videos opposite to their sexual orientation both groups showed absent hypothalamic activation. Moreover, the activation pattern found in both groups suggests that stimuli of opposite sexual orientation triggered intense autonomic response and may be perceived, at least to some extent, as aversive.
Neural circuits of disgust induced by sexual stimuli in homosexual and heterosexual men: an fMRI study.
Zhang Minming,Hu Shaohua,Xu Lijuan,Wang Qidong,Xu Xiaojun,Wei Erqing,Yan Leqin,Hu Jianbo,Wei Ning,Zhou Weihua,Huang Manli,Xu Yi
European journal of radiology
Few studies demonstrated neural circuits related to disgust were influenced by internal sexual orientation in male. Here we used fMRI to study the neural responses to disgust in homosexual and heterosexual men to investigate that issue. Thirty-two healthy male volunteers (sixteen homosexual and sixteen heterosexual) were scanned while viewing alternating blocks of three types of erotic film: heterosexual couples (F-M), male homosexual couples (M-M), and female homosexual couples (F-F) engaged in sexual activity. All the participants rated their level of disgust and sexual arousal as well. The F-F and M-M stimuli induced disgust in homosexual and heterosexual men, respectively. The common activations related to disgusting stimuli included: bilateral frontal gyrus and occipital gyrus, right middle temporal gyrus, left superior temporal gyrus, right cerebellum, and right thalamus. Homosexual men had greater neural responses in the left medial frontal gyrus than did heterosexual men to the sexual disgusting stimuli; in contrast, heterosexual men showed significantly greater activation than homosexual men in the left cuneus. ROI analysis showed that negative correlation were found between the magnitude of MRI signals in the left medial frontal gyrus and scores of disgust in homosexual subjects (p<0.05). This study indicated that there were regions in common as well as regions specific for each type of erotic stimuli during disgust of homosexual and heterosexual men.
[Brain mechanisms of male sexual function].
Wang Ying,Dou Xin,Li Jun-Fa,Luo Yan-Lin
Zhonghua nan ke xue = National journal of andrology
In this paper, we reviewed the brain imaging studies of male sexual function in recent years from three aspects: the brain mechanism of normal sexual function, the brain mechanism of sexual dysfunction, and the mechanism of drug therapy for sexual dysfunction. Studies show that the development stages of male sexual activities, such as the excitement phase, plateau phase and orgasm phase, are controlled by different neural networks. The mesodiencephalic transition zone may play an important role in the start up of male ejaculation. There are significant differences between sexual dysfunction males and normal males in activation patterns of the brain in sexual arousal. The medial orbitofrontal cortex and inferior frontal gyrus in the abnormal activation pattern are correlated with sexual dysfunction males in sexual arousal. Serum testosterone and morphine are commonly used drugs for male sexual dysfunction, whose mechanisms are to alter the activating levels of the medial orbitofrontal cortex, insula, claustrum and inferior temporal gyrus.
Brain processing of visual sexual stimuli in healthy men: a functional magnetic resonance imaging study.
Mouras Harold,Stoléru Serge,Bittoun Jacques,Glutron Dominique,Pélégrini-Issac Mélanie,Paradis Anne-Lise,Burnod Yves
The brain plays a central role in sexual motivation. To identify cerebral areas whose activation was correlated with sexual desire, eight healthy male volunteers were studied with functional magnetic resonance imaging (fMRI). Visual stimuli were sexually stimulating photographs (S condition) and emotionally neutral photographs (N condition). Subjective responses pertaining to sexual desire were recorded after each condition. To image the entire brain, separate runs focused on the upper and the lower parts of the brain. Statistical Parametric Mapping was used for data analysis. Subjective ratings confirmed that sexual pictures effectively induced sexual arousal. In the S condition compared to the N condition, a group analysis conducted on the upper part of the brain demonstrated an increased signal in the parietal lobes (superior parietal lobules, left intraparietal sulcus, left inferior parietal lobule, and right postcentral gyrus), the right parietooccipital sulcus, the left superior occipital gyrus, and the precentral gyri. In addition, a decreased signal was recorded in the right posterior cingulate gyrus and the left precuneus. In individual analyses conducted on the lower part of the brain, an increased signal was found in the right and/or left middle occipital gyrus in seven subjects, and in the right and/or left fusiform gyrus in six subjects. In conclusion, fMRI allows to identify brain responses to visual sexual stimuli. Among activated regions in the S condition, parietal areas are known to be involved in attentional processes directed toward motivationally relevant stimuli, while frontal premotor areas have been implicated in motor preparation and motor imagery. Further work is needed to identify those specific features of the neural responses that distinguish sexual desire from other emotional and motivational states.
Self-related processing in the sexual domain: a parametric event-related fMRI study reveals neural activity in ventral cortical midline structures.
Heinzel Alexander,Walter Martin,Schneider Felix,Rotte Michael,Matthiae Christian,Tempelmann Claus,Heinze Hans-Jochen,Bogerts Bernhard,Northoff Georg
Self-related processing, reflecting the evaluation of environmental signals with regard to personal relevance, is fundamental for decision-making and subsequent behavioral responses. While self-related processing has already been investigated in several domains, one important domain, the sexual domain, has been spared so far. Recent imaging studies suggest that self-related processing in different domains involves common regions in medial orbitofrontal and prefrontal cortex, the so-called ventral cortical midline structures (CMS). However, the same regions have also been implicated in sexual arousal, especially with regard to emotional processing in sexual arousal. Therefore it remains unclear whether this involvement of ventral cortical midline regions reflects emotional processing in sexual arousal or associated self-relatedness. We here report data from a parametric event-related fMRI study that investigated the neural correlates of self-related processing in sexual arousal, using erotic pictures from the International Affective Picture System. It was found that self-related activity associated with sexual arousal showed neural activity in ventral CMS regions such as the venteromedial prefrontal cortex (VMPFC) and the perigenual anterior cingulate cortex (PACC), while self-related activity not associated with sexual arousal showed neural activity in the dorsomedial prefrontal cortex (DMPFC). Our study indicates that self-relatedness may be considered a crucial component in sexual arousal that is mediated by neural activity in ventral cortical midline structures.
Neural activation toward erotic stimuli in homosexual and heterosexual males.
Kagerer Sabine,Klucken Tim,Wehrum Sina,Zimmermann Mark,Schienle Anne,Walter Bertram,Vaitl Dieter,Stark Rudolf
The journal of sexual medicine
INTRODUCTION:Studies investigating sexual arousal exist, yet there are diverging findings on the underlying neural mechanisms with regard to sexual orientation. Moreover, sexual arousal effects have often been confounded with general arousal effects. Hence, it is still unclear which structures underlie the sexual arousal response in homosexual and heterosexual men. AIM:Neural activity and subjective responses were investigated in order to disentangle sexual from general arousal. Considering sexual orientation, differential and conjoint neural activations were of interest. METHODS:The functional magnetic resonance imaging (fMRI) study focused on the neural networks involved in the processing of sexual stimuli in 21 male participants (11 homosexual, 10 heterosexual). Both groups viewed pictures with erotic content as well as aversive and neutral stimuli. The erotic pictures were subdivided into three categories (most sexually arousing, least sexually arousing, and rest) based on the individual subjective ratings of each participant. MAIN OUTCOME MEASURES:Blood oxygen level-dependent responses measured by fMRI and subjective ratings. RESULTS:A conjunction analysis revealed conjoint neural activation related to sexual arousal in thalamus, hypothalamus, occipital cortex, and nucleus accumbens. Increased insula, amygdala, and anterior cingulate gyrus activation could be linked to general arousal. Group differences emerged neither when viewing the most sexually arousing pictures compared with highly arousing aversive pictures nor compared with neutral pictures. CONCLUSION:Results suggest that a widespread neural network is activated by highly sexually arousing visual stimuli. A partly distinct network of structures underlies sexual and general arousal effects. The processing of preferred, highly sexually arousing stimuli recruited similar structures in homosexual and heterosexual males.
Neural correlates of sexual arousal in homosexual and heterosexual men.
Safron Adam,Barch Bennett,Bailey J Michael,Gitelman Darren R,Parrish Todd B,Reber Paul J
Men exhibit much higher levels of genital and subjective arousal to sexual stimuli containing their preferred sex than they do to stimuli containing only the nonpreferred sex. This study used event-related functional magnetic resonance imaging to investigate how this category-specific pattern would be reflected in the brains of homosexual (n = 11) and heterosexual (n = 11) men. Comparisons of activation to preferred sexual stimuli, nonpreferred sexual stimuli, and sports stimuli revealed large networks correlated with sexual arousal, spanning multiple cortical and subcortical areas. Both homosexual and heterosexual men exhibited category-specific arousal in brain activity. Within the amygdala, greater preference-related activity was observed in homosexual men, but it is unclear whether this is a cause or a consequence of their sexuality. In a subsequent analysis of regions hypothesized to support arousal, both participant groups demonstrated widespread increases in evoked activity for preferred stimuli. Aggregate data from these regions produced significant differences between stimulus types in 16 out of 22 participants. Significant activational differences matched reported sexual orientation in 15 of these 16 participants, representing an advance in psychophysiological measures of arousal.
Neural Correlates of Sexual Orientation in Heterosexual, Bisexual, and Homosexual Men.
Safron Adam,Sylva David,Klimaj Victoria,Rosenthal A M,Li Meng,Walter Martin,Bailey J Michael
Studies of subjective and genital sexual arousal in monosexual (i.e. heterosexual and homosexual) men have repeatedly found that erotic stimuli depicting men's preferred sex produce strong responses, whereas erotic stimuli depicting the other sex produce much weaker responses. Inconsistent results have previously been obtained in bisexual men, who have sometimes demonstrated distinctly bisexual responses, but other times demonstrated patterns more similar to those observed in monosexual men. We used fMRI to investigate neural correlates of responses to erotic pictures and videos in heterosexual, bisexual, and homosexual men, ages 25-50. Sixty participants were included in video analyses, and 62 were included in picture analyses. We focused on the ventral striatum (VS), due to its association with incentive motivation. Patterns were consistent with sexual orientation, with heterosexual and homosexual men showing female-favoring and male-favoring responses, respectively. Bisexual men tended to show less differentiation between male and female stimuli. Consistent patterns were observed in the whole brain, including the VS, and also in additional regions such as occipitotemporal, anterior cingulate, and orbitofrontal cortices. This study extends previous findings of gender-specific neural responses in monosexual men, and provides initial evidence for distinct brain activity patterns in bisexual men.
Neural correlates of sexual arousal in the spinal cords of able-bodied men: a spinal fMRI investigation.
Kozyrev Natalie,Figley Chase R,Alexander Marcalee S,Richards J Scott,Bosma Rachael L,Stroman Patrick W
Journal of sex & marital therapy
The purpose of this study was to determine whether spinal cord functional magnetic resonance imaging could be used to map neural activity throughout the lower thoracic, lumbar, and sacral spinal cord regions during sexual arousal in healthy men. The authors found that viewing erotic films and genital self-stimulation elicited predominantly increased signal, indicative of amplified neuronal input to the dorsal and ventral horns and in the autonomic preganglionic nuclei of the lower thoracic, lumbar, and sacral spinal cord. In addition, linear regression analyses revealed a number of robust correlations (|R| ≥ 0.7) between signal intensity changes in these spinal cord regions and self-reported ratings of mental and physical sexual arousal. Taken together, these results demonstrate that spinal cord functional magnetic resonance imaging is an effective and sensitive technique for mapping the neural correlates of sexual arousal in the spinal cords of able-bodied men. Most important, the results from this study indicate that spinal cord functional magnetic resonance imaging may have important applications as a clinical tool for assessing and mapping the changes that occur in the spinal cords of men suffering from sexual dysfunction as a result of spinal cord trauma.
Time-course analysis of the neuroanatomical correlates of sexual arousal evoked by erotic video stimuli in healthy males.
Sundaram Thirunavukkarasu,Jeong Gwang-Woo,Kim Tae-Hoon,Kim Gwang-Won,Baek Han-Su,Kang Heoung-Keun
Korean journal of radiology
OBJECTIVE:To assess the dynamic activations of the key brain areas associated with the time-course of the sexual arousal evoked by visual sexual stimuli in healthy male subjects. MATERIALS AND METHODS:Fourteen right-handed heterosexual male volunteers participated in this study. Alternatively combined rest period and erotic video visual stimulation were used according to the standard block design. In order to illustrate and quantify the spatiotemporal activation patterns of the key brain regions, the activation period was divided into three different stages as the EARLY, MID and LATE stages. RESULTS:For the group result (p < 0.05), when comparing the MID stage with the EARLY stage, a significant increase of the brain activation was observed in the areas that included the inferior frontal gyrus, the supplementary motor area, the hippocampus, the head of the caudate nucleus, the midbrain, the superior occipital gyrus and the fusiform gyrus. At the same time, when comparing the EARLY stage with the MID stage, the putamen, the globus pallidus, the pons, the thalamus, the hypothalamus, the lingual gyrus and the cuneus yielded significantly increased activations. When comparing the LATE stage with the MID stage, all the above mentioned brain regions showed elevated activations except the hippocampus. CONCLUSION:Our results illustrate the spatiotemporal activation patterns of the key brain regions across the three stages of visual sexual arousal.
Dynamic subcortical blood flow during male sexual activity with ecological validity: a perfusion fMRI study.
Georgiadis Janniko R,Farrell Michael J,Boessen Ruud,Denton Derek A,Gavrilescu Maria,Kortekaas Rudie,Renken Remco J,Hoogduin Johannes M,Egan Gary F
This study used arterial spin labeling (ASL) fMRI to measure brain perfusion in a group of healthy men under conditions that closely resembled customary sexual behavior. Serial perfusion measures for 30 min during two self-limited periods of partnered penis stimulation, and during post-stimulatory periods, revealed novel sexual activity-related cerebral blood flow (rCBF) changes, mainly in subcortical parts of the brain. Ventral pallidum rCBF was highest during the onset of penile erection, and lowest after the termination of penis stimulation. The perceived level of sexual arousal showed the strongest positive association with rCBF in the right basal forebrain. In addition, our results demonstrate that distinct subregions of the hypothalamus and cingulate cortex subserve opposite functions during human male sexual behavior. The lateral hypothalamus and anterior part of the middle cingulate cortex showed increased rCBF correlated with penile erection. By contrast, the anteroventral hypothalamus and subgenual anterior cingulate cortex exhibited rCBF changes correlated with penile detumescence after penile stimulation. Continuous rapid and high-resolution brain perfusion imaging during normal sexual activity has provided novel insights into the central mechanisms that control male sexual arousal.
The functional neuroanatomy of male psychosexual and physiosexual arousal: a quantitative meta-analysis.
Poeppl Timm B,Langguth Berthold,Laird Angela R,Eickhoff Simon B
Human brain mapping
Reproductive behavior is mandatory for conservation of species and mediated by a state of sexual arousal (SA), involving both complex mental processes and bodily reactions. An early neurobehavioral model of SA proposes cognitive, emotional, motivational, and autonomic components. In a comprehensive quantitative meta-analysis on previous neuroimaging findings, we provide here evidence for distinct brain networks underlying psychosexual and physiosexual arousal. Psychosexual (i.e., mental sexual) arousal recruits brain areas crucial for cognitive evaluation, top-down modulation of attention and exteroceptive sensory processing, relevance detection and affective evaluation, as well as regions implicated in the representation of urges and in triggering autonomic processes. In contrast, physiosexual (i.e., physiological sexual) arousal is mediated by regions responsible for regulation and monitoring of initiated autonomic processes and emotions and for somatosensory processing. These circuits are interconnected by subcortical structures (putamen and claustrum) that provide exchange of sensorimotor information and crossmodal processing between and within the networks. Brain deactivations may imply attenuation of introspective processes and social cognition, but be necessary to release intrinsic inhibition of SA.
Neural activations of the acquisition of conditioned sexual arousal: effects of contingency awareness and sex.
Klucken Tim,Schweckendiek Jan,Merz Christian J,Tabbert Katharina,Walter Bertram,Kagerer Sabine,Vaitl Dieter,Stark Rudolf
The journal of sexual medicine
INTRODUCTION:Learning processes like classical conditioning are involved in mediating sexual behavior. Yet, the neural bases underlying these processes have not been investigated so far. AIM:The aim of this study was to explore neural activations of classical conditioning of sexual arousal with respect to sex differences and contingency awareness. METHODS:In the acquisition phase, a geometric figure (CS+) was presented for 8 seconds and was followed by highly sexual arousing pictures (UCS), whereas another figure (CS-) predicted neutral pictures. Ratings and contingency awareness were assessed after the entire conditioning procedure. Forty subjects (20 females) were classified into one of four groups according to their sex and the development of contingency awareness (aware females, aware males, unaware females, and unaware males). MAIN OUTCOME MEASURES:Blood oxygen level dependent (BOLD) responses measured by functional magnetic resonance imaging (fMRI), skin conductance responses (SCRs), and subjective ratings. RESULTS:fMRI analysis showed two effects (awareness and sex) when comparing CS+ with CS-: (i) aware compared to unaware subjects showed enhanced differentiation (e.g., ventral striatum, orbitofrontal cortex, occipital cortex); and (ii) men showed increased activity compared to women in the amygdala, thalamus, and brainstem. CS+ and CS- ratings differed in aware subjects only. However, no conditioned SCRs occurred in any group. CONCLUSION:The increased activity in men is in line with theories postulating that men are generally more prone to conditioning of sexual arousal. Further, contingency awareness seems to be an important factor in appetitive learning processes, which facilitates conditioning processes.
Gender commonalities and differences in the neural processing of visual sexual stimuli.
Wehrum Sina,Klucken Tim,Kagerer Sabine,Walter Bertram,Hermann Andrea,Vaitl Dieter,Stark Rudolf
The journal of sexual medicine
INTRODUCTION:Few studies so far have directly compared the neural processing of visual sexual stimuli in men and women. Also, most of these studies only compared sexual with neutral stimuli, making it difficult to disentangle sexual stimulus processing from general emotional processing. AIM:The current study aimed to explore gender commonalities and differences in neural activity associated with the processing of visual sexual stimuli in a large sample of 50 men and 50 women. In order to disentangle effects of sexual processing from those of general emotional processing, we employed sexual, neutral, positive, and negative emotional pictures. METHODS:Subjects passively viewed sexual, neutral, positive, and negative emotional pictures during a functional magnetic resonance imaging (fMRI) session. Pictures were presented in 24 blocks of five pictures each. Every block was rated immediately after its presentation with respect to valence, arousal, and sexual arousal. MAIN OUTCOME MEASURES:Blood oxygen level dependent responses measured by fMRI and subjective ratings. RESULTS:fMRI analysis revealed a distributed network for the neural processing of sexual stimuli comprising the hypothalamus, the nucleus accumbens, as well as orbitofrontal, occipital, and parietal areas. This network could be identified (i) for both men and women, with men showing overall stronger activations than women and (ii) independent of general emotional arousal or valence effects. CONCLUSION:Our data speak in favor of a common neural network associated with the processing of visual sexual stimuli in men and women. Apart from the observed gender commonalities, overall stronger responses in men were observed that might indicate stronger sexual responsivity in men.
Distinguishing specific sexual and general emotional effects in fMRI-subcortical and cortical arousal during erotic picture viewing.
Walter Martin,Bermpohl Felix,Mouras Harold,Schiltz Kolja,Tempelmann Claus,Rotte Michael,Heinze Hans Jochen,Bogerts Bernhard,Northoff Georg
Sexual activity involves excitement with high arousal and pleasure as typical features of emotions. Brain activations specifically related to erotic feelings and those related to general emotional processing are therefore hard to disentangle. Using fMRI in 21 healthy subjects (11 males and 10 females), we investigated regions that show activations specifically related to the viewing of sexually intense pictures while controlling for general emotional arousal (GEA) or pleasure. Activations in the ventral striatum and hypothalamus were found to be modulated by the stimulus' specific sexual intensity (SSI) while activations in the anterior cingulate cortex were associated with an interaction between sexual intensity and emotional valence. In contrast, activation in other regions like the dorsomedial prefrontal cortex, the mediodorsal thalamus and the amygdala was associated only with a general emotional component during sexual arousal. No differences were found in these effects when comparing females and males. Our findings demonstrate for the first time neural differentiation between emotional and sexual components in the neural network underlying sexual arousal.
Neural correlates of subliminally presented visual sexual stimuli.
Wernicke Martina,Hofter Corinna,Jordan Kirsten,Fromberger Peter,Dechent Peter,Müller Jürgen L
Consciousness and cognition
In the context of forensic psychiatry, it is crucial that diagnoses of deviant sexual interests are resistant to manipulation. In a first attempt to promote the development of such tools, the current fMRI study focusses on the examination of hemodynamic responses to preferred, in contrast to non-preferred, sexual stimuli with and without explicit sexual features in 24 healthy heterosexual subjects. The subliminal stimulus presentation of sexual stimuli could be a new approach to reduce vulnerability to manipulation. Meaningful images and scrambled images were applied as masks. Recognition performance was low, but interestingly, sexual preference and explicitness modulated stimulus visibility, suggesting interactions between networks of sexual arousal and consciousness. With scrambled masks, higher activations for sexually preferred images and for explicit images were found in areas associated with sexual arousal (Stoleru, Fonteille, Cornelis, Joyal, & Moulier, 2012). We conclude that masked sexual stimuli can evoke activations in areas associated with supraliminal induced sexual arousal.
A quantitative meta-analysis on cue-induced male sexual arousal.
Kühn Simone,Gallinat Jürgen
The journal of sexual medicine
INTRODUCTION:Visually induced sexual arousal is a common occurrence in human behavior. The cerebral underpinnings of this response have been explored in recent neuroimaging studies. AIM:We set out to test the strength of evidence for the presence of a core network of brain regions involved in male sexual arousal elicited by erotic stimuli. METHODS:Eleven functional magnetic resonance imaging studies that presented erotic visual stimuli and compared the associated brain activity with the brain activity elicited by neutral visual stimuli were identified. MAIN OUTCOMES MEASURES:Activation likelihood estimation was employed to perform quantitative meta-analyses on coordinates of brain activation in order to assess significant concordance across studies. RESULTS:The meta-analysis included studies on heterosexual males and revealed consistent activation in the hypothalamus, thalamus, amygdala, anterior cingulate gyrus (ACC), insula, fusiform gyrus, precentral gyrus, parietal cortex, and occipital cortex across studies. Moreover, we explored brain responses associated with a physiological marker of sexual arousal (penile tumescence) and found concurrence in hypothalamus, thalamus, bilateral insula, ACC, postcentral gyrus, and occipital gyrus. CONCLUSIONS:This is the first quantitative meta-analysis on sexual cue reactivity and identifies a neural network consisting of cognitive (parietal cortex, ACC, thalamus, insula), emotional (amygdala, insula), motivational (precentral gyrus, parietal cortex), and physiological (hypothalamus/thalamus, insula) components constituting a core circuit of male sexual arousal in humans.
At the second glance: stability of neural responses toward visual sexual stimuli.
Wehrum-Osinsky Sina,Klucken Tim,Kagerer Sabine,Walter Bertram,Hermann Andrea,Stark Rudolf
The journal of sexual medicine
INTRODUCTION:Studies investigating the neural responses toward sexual stimuli can provide an important basis for further understanding disorders of sexual functioning. Although our knowledge of the neural correlates of sexual stimulus processing has increased considerably in the last decade, the stability of the observed effects in studies on neural sexual responses has been rather neglected. AIMS:The current study aimed to test the stability of behavioral and neural responses to visual sexual stimuli in men and women over a time span of 1 to 1.5 years. To disentangle valence and arousal-related aspects of sexual stimulus processing, we employed not only sexual and neutral, but also positive and negative emotional stimuli. METHODS:A sample of 56 subjects (24 women) was assessed twice, with an interval of 1 to 1.5 years between assessments. During a functional magnetic resonance imaging (fMRI) session, participants passively viewed sexual, neutral, positive, and negative emotional pictures. Pictures were presented in 24 blocks of five pictures each. Every block was rated immediately after its presentation with respect to valence, arousal, and sexual arousal. MAIN OUTCOME MEASURES:Blood oxygen level dependent (BOLD) responses measured by fMRI and stimulus ratings. RESULTS:fMRI analyses revealed a distributed network involved in the processing of sexual stimuli, with large parts of this network being consistently activated at both assessment points. Nucleus accumbens, anterior cingulate, occipital and parietal cortex showed the most robust results with respect to group stability. Responses of anterior cingulate, orbitofrontal, parietal and occipital cortex showed interindividual stability. Gender differences were restricted to a few regions of interest. CONCLUSIONS:Our data indicate stability of neural responses toward sexual stimuli not only on the group but also on the individual level. Activation of parietal and occipital cortex might reflect a trait like character of attention related responses toward sexual stimuli.
Brain activation in response to visually evoked sexual arousal in male-to-female transsexuals: 3.0 tesla functional magnetic resonance imaging.
Oh Seok-Kyun,Kim Gwang-Won,Yang Jong-Chul,Kim Seok-Kwun,Kang Heoung-Keun,Jeong Gwang-Woo
Korean journal of radiology
OBJECTIVE:This study used functional magnetic resonance imaging (fMRI) to contrast the differential brain activation patterns in response to visual stimulation with both male and female erotic nude pictures in male-to-female (MTF) transsexuals who underwent a sex reassignment surgery. MATERIALS AND METHODS:A total of nine healthy MTF transsexuals after a sex reassignment surgery underwent fMRI on a 3.0 Tesla MR Scanner. The brain activation patterns were induced by visual stimulation with both male and female erotic nude pictures. RESULTS:The sex hormone levels of the postoperative MTF transsexuals were in the normal range of healthy heterosexual females. The brain areas, which were activated by viewing male nude pictures when compared with viewing female nude pictures, included predominantly the cerebellum, hippocampus, putamen, anterior cingulate gyrus, head of caudate nucleus, amygdala, midbrain, thalamus, insula, and body of caudate nucleus. On the other hand, brain activation induced by viewing female nude pictures was predominantly observed in the hypothalamus and the septal area. CONCLUSION:Our findings suggest that distinct brain activation patterns associated with visual sexual arousal in postoperative MTF transsexuals reflect their sexual orientation to males.
Neural correlates of gender differences in distractibility by sexual stimuli.
Strahler J,Kruse O,Wehrum-Osinsky S,Klucken T,Stark R
Attentional interference control is a prominent feature of human cognition. To what extent sexual stimuli attract attention and interfere with cognitive tasks has still little been studied. Our study aimed to identify associations between attentional interference, sexual arousal, trait sexual motivation, and neural activity to sexual distractors while accounting for gender differences. Therefore, the present study examined the neural correlates of attentional interference by arousing sexual distractors using functional magnetic resonance imaging (fMRI). Fifty women and 47 men underwent fMRI while indicating the orientation of two lines (equal or unequal) next to an explicit sexual (as compared to a neutral) picture. Results confirmed prolonged response times when a sexual image was shown. There was neither a difference between genders nor an effect of sexual arousal ratings or trait sexual motivation on distractibility. Neural activity specific to sexual images was found in brain regions implicated in motivation and reward processing. Men as compared to women showed stronger responses in the nucleus caudatus, the anterior cingulate cortex, and the nucleus accumbens. Trait sexual motivation was selectively correlated with nucleus caudatus activity. Taken together, findings support the notion that even when not in the focus, sexual images activate the brains' reward circuitry. Men's higher sensitivity to the rewarding value of sexual cues may be critical for their higher risk of addictive/compulsive sexual behaviors.
The neural basis of sex differences in sexual behavior: A quantitative meta-analysis.
Poeppl Timm B,Langguth Berthold,Rupprecht Rainer,Safron Adam,Bzdok Danilo,Laird Angela R,Eickhoff Simon B
Frontiers in neuroendocrinology
Sexuality as to its etymology presupposes the duality of sexes. Using quantitative neuroimaging meta-analyses, we demonstrate robust sex differences in the neural processing of sexual stimuli in thalamus, hypothalamus, and basal ganglia. In a narrative review, we show how these relate to the well-established sex differences on the behavioral level. More specifically, we describe the neural bases of known poor agreement between self-reported and genital measures of female sexual arousal, of previously proposed male proneness to affective sexual conditioning, as well as hints of unconscious activation of bonding mechanisms during sexual stimulation in women. In summary, our meta-analytic review demonstrates that neurofunctional sex differences during sexual stimulation can account for well-established sex differences in sexual behavior.
Neural Responses to Sexual Stimuli in Heterosexual and Homosexual Men and Women: Men's Responses Are More Specific.
Safron Adam,Sylva David,Klimaj Victoria,Rosenthal A M,Bailey J Michael
Archives of sexual behavior
Patterns of genital arousal in response to gendered sexual stimuli (i.e., sexual stimuli presenting members of only one sex at a time) are more predictive of men's than of women's sexual orientations. Additional lines of evidence may shed light on the nature of these differences. We measured neural activation in homosexual and heterosexual men and women using fMRI while they viewed three kinds of gendered sexual stimuli: pictures of nude individuals, pictures of same-sex couples interacting, and videos of individuals self-stimulating. The primary neural region of interest was the ventral striatum (VS), an area of central importance for reward processing. For all three kinds of stimuli and for both VS activation and self-report, men's responses were more closely related to their sexual orientations compared with women's. Furthermore, men showed a much greater tendency to respond more positively to stimuli featuring one sex than to stimuli featuring the other sex, leading to higher correlations among men's responses as well as higher correlations between men's responses and their sexual orientations. Whole-brain analyses identified several other regions showing a similar pattern to the VS, and none showed an opposite pattern. Because fMRI is measured identically in men and women, our results provide the most direct evidence to date that men's sexual arousal patterns are more gender specific than women's.
The Impact of Sexual Arousal and Emotion Regulation on Men's Sexual Aggression Proclivity.
Craig Amber N,Peterson Zoë D,Janssen Erick,Goodrich Mba David,Heiman Julia R
Journal of interpersonal violence
Extant literature supports a relationship between sexual arousal and increased likelihood of sexually coercive behavior in men. The present study investigated the impact of sexual arousal on sexual coercion proclivity and the degree to which emotion regulation moderated this relationship in the context of two separate affect inductions. We predicted that sexual arousal would more strongly predict sexual coercion likelihood for men scoring lower on emotion regulation ability compared with men with above average emotion regulation abilities. Male participants with ( = 38) and without ( = 40) self-reported histories of sexual coercion were recruited from urban sexually transmitted infection testing clinics. Participants completed a measure of emotion regulation, underwent a positive and negative affect induction, viewed an erotic video, and reported on their level of sexual arousal immediately prior to completing a hypothetical sexual coercion likelihood laboratory task. Relationships between emotion regulation, sexual arousal, and sexual coercion likelihood were examined using moderation analyses. Sexual arousal was associated with greater reported sexual coercion likelihood. For men with poorer emotion regulation, sexual arousal significantly and positively predicted sexual coercion likelihood in the positive affect condition. Sexual arousal did not significantly predict sexual coercion for men with above average emotion regulation. Findings may have implications for the assessment of individual risk for coercive sexual behavior as well as primary prevention efforts.
Neural substrates of sexual arousal in heterosexual males: event-related fMRI investigation.
Seok Ji-Woo,Sohn Jin-Hun,Cheong Chaejoon
Journal of physiological anthropology
BACKGROUND:Sexual behavior is an important role for the survival of species. The advancement of brain imaging methods has enabled the understanding of the brain mechanism related to sexual arousal. The previous studies on the brain mechanism related to sexual arousal have mostly conducted on block design paradigm. METHODS:Despite its requirement for stricter experimental control, the event-related paradigm is known to be more efficient in detecting instant emotional and cognitive responses. The paradigm also enables the observation of hemodynamic responses through time. Therefore, this study used the event-related fMRI to examine the brain activation in various areas associated with sexual arousal as well as changes in hemodynamic responses with time. RESULTS:Strong activations were observed in the various areas associated with sexual arousal comprised of various factors: (1) activation areas related to cognitive factors: the occipital lobe and parietal lobe; (2) activation areas related to emotional factors: the thalamus and amygdala; (3) activation areas related to motivational factors: the anterior cingulate gyrus, orbitofrontal cortex, and insula; and (4) activation areas related to physiological factors: the precentral gyrus, putamen, and globus pallidus. We also identified the activation of the putamen and globus pallidus that were not well observed in previous block design studies. In the result of the hemodynamic response, the neural activity in those areas showed more transient aspects of the hemodynamic responses relative to the neural activity of other areas. CONCLUSIONS:These results suggested that the event-related paradigm is better at detecting the neural activity of the brain regions, which tend to appear suddenly, but disappear soon.
Endocrinologic Control of Men's Sexual Desire and Arousal/Erection.
Corona Giovanni,Isidori Andrea M,Aversa Antonio,Burnett Arthur L,Maggi Mario
The journal of sexual medicine
INTRODUCTION:Several hormones and neurotransmitters orchestrate men's sexual response, including the appetitive (sexual desire) and consummative (arousal and penile erection) phases. AIM:To provide an overview and recommendations regarding endocrinologic control of sexual desire and arousal and erection and their disturbances. METHODS:Medical literature was reviewed by the subcommittee of the International Consultation of Sexual Medicine, followed by extensive internal discussion, and then public presentation and discussion with other experts. The role of pituitary (prolactin, oxytocin, growth hormone, and α-melanocyte-stimulating hormone), thyroid, and testicular hormones was scrutinized and discussed. MAIN OUTCOME MEASURES:Recommendations were based on grading of evidence-based medical literature, followed by interactive discussion. RESULTS:Testosterone has a primary role in controlling and synchronizing male sexual desire and arousal, acting at multiple levels. Accordingly, meta-analysis indicates that testosterone therapy for hypogonadal individuals can improve low desire and erectile dysfunction. Hyperprolactinemia is associated with low desire that can be successfully corrected by appropriate treatments. Oxytocin and α-melanocyte-stimulating hormone are important in eliciting sexual arousal; however, use of these peptides, or their analogs, for stimulating sexual arousal is still under investigation. Evaluation and treatment of other endocrine disorders are suggested only in selected cases. CONCLUSION:Endocrine abnormalities are common in patients with sexual dysfunction. Their identification and treatment is strongly encouraged in disturbances of sexual desire and arousal.
Neural pathways in processing of sexual arousal: a dynamic causal modeling study.
Seok J-W,Park M-S,Sohn J-H
International journal of impotence research
Three decades of research have investigated brain processing of visual sexual stimuli with neuroimaging methods. These researchers have found that sexual arousal stimuli elicit activity in a broad neural network of cortical and subcortical brain areas that are known to be associated with cognitive, emotional, motivational and physiological components. However, it is not completely understood how these neural systems integrate and modulated incoming information. Therefore, we identify cerebral areas whose activations were correlated with sexual arousal using event-related functional magnetic resonance imaging and used the dynamic causal modeling method for searching the effective connectivity about the sexual arousal processing network. Thirteen heterosexual males were scanned while they passively viewed alternating short trials of erotic and neutral pictures on a monitor. We created a subset of seven models based on our results and previous studies and selected a dominant connectivity model. Consequently, we suggest a dynamic causal model of the brain processes mediating the cognitive, emotional, motivational and physiological factors of human male sexual arousal. These findings are significant implications for the neuropsychology of male sexuality.
[Connection between subjective sexual arousal and genital response: differences between men and women].
Sierra Juan Carlos,Álvarez-Muelas Ana,Arcos-Romero Ana Isabel,Calvillo Cristóbal,Torres-Obregón Reyna,Granados Reina
Revista internacional de andrologia
OBJECTIVE:The level of agreement between subjective and objective measures of sexual arousal is referred as sexual concordance. Sex is one of the principal moderators and there is a higher level of correspondence in men than in women. The aim of this study is to evaluate the predictive validity of the scales Ratings of Sexual Arousal (RSA) and Ratings of Genital Sensations (RGS), relating their scores with the genital response to visual sexual stimuli in men and women. MATERIAL AND METHOD:A sample of 159 young heterosexuals was used (69 men and 90 women) which completed, firstly, a sociodemographic and sexual story questionnaire, the Sexual Inhibition/Sexual Excitation Scales Short-Form and the SOS-6. At the laboratory, they were exposed to a neutral film and to an explicit sexual content film. The subjective sexual arousal was evaluated with the RSA and RGS scales and the genital response was registered through a plethysmography (men) and a photo-plethysmography (women). RESULTS:Significant correlations were obtained between subjective and objective sexual arousal only in men. The RGS scale has the capacity to predict the erection response toward sexual stimuli. CONCLUSIONS:The theory of differences in sexual concordance between men and women was endorsed. Modest evidence about the predictive validity of the subjective sexual arousal evaluation scale was found only in men. It arises the need for subjective and objective assessment of sexual arousal, in clinical settings and research area.
Neural Representation of Subjective Sexual Arousal in Men and Women.
Parada Mayte,Gérard Marina,Larcher Kevin,Dagher Alain,Binik Yitzchak M
The journal of sexual medicine
INTRODUCTION:Studies investigating brain indices of sexual arousal have begun to elucidate the brain's role in processing subjective arousal; however, most research has focused on men, used discrete ratings of subjective arousal, and used stimuli too short to induce significant arousal in women. AIM:To examine brain regions modulated by changes in subjective sexual arousal (SSA) rating intensity in men and women. METHODS:Two groups (20 men, 20 women) viewed movie clips (erotic or humorous) while continuously evaluating changes in their SSA using a Likert-like scale (0 = not aroused, 10 = most aroused) and answering discrete questions about liking the movies and wanting sexual stimulation. Brain activity was measured using functional magnetic resonance imaging. MAIN OUTCOME MEASURES:Blood oxygen level-dependent responses and continuous and discrete measurements of sexual arousal. RESULTS:Erotic movies induced significant SSA in men and women. No sex difference in mean SSA was found in response to the erotic movies on continuous or discrete measurements. Several brain regions were correlated with changes in SSA. Parametric modulation with rating intensity showed a specific group of regions within the parietal lobe that showed significant differences in activity among low, medium, and high SSA. CONCLUSION:Multiple regions were concordant with changes in SSA; however, a subset of regions in men and women was modulated by SSA intensity, a subset previously linked to attentional processes, monitoring of internal body representation, and processing of sensory information from the genitals. This study highlights that similar brain regions are activated during subjective assessment of sexual arousal in men and women. The data further highlight the fact that SSA is a complex phenomenon made up of multiple interoceptive and attentional processes.
The Impacts of Sexual Arousal and Its Suppression on Executive Functioning.
Suchy Yana,Holmes Laura G,Strassberg Donald S,Gillespie Austin A,Nilssen A Renee,Niermeyer Madison A,Huntbach Bryce A
Journal of sex research
Suppression of certain types of reflexive emotional responses is thought to temporarily deplete executive functions (EF), as evidenced by poorer performance on measures of EF, but does not deplete other, lower-order cognitive processes. This study examined whether similar decrements in performance on EF tests would occur following suppression of sexual arousal. A sample of 44 male college students underwent baseline cognitive assessment (EF and lower-order cognitive processes), followed by experimental manipulation consisting of exposure to sexually explicit audiovisual stimuli. Sexual arousal was monitored using penile plethysmography. In this study, 21 participants were assigned to a suppression condition and were instructed to suppress sexual arousal during the video, while 23 were assigned to an arousal condition and were instructed to allow themselves to become aroused. Following experimental manipulation, cognition was reassessed. Unexpectedly, results showed EF decrements in the arousal group but not in the suppression group. As expected, only EF was affected by experimental manipulation, with no group differences in lower-order cognitive processes. Thus, the findings suggest that sexual arousal is associated with temporary decrements in EF performance, at least among young, primarily White, male college students. The results contribute to understanding why sexually charged situations are sometimes associated with poor decisions or unsafe/reckless sexual practices.
The Impact of Sexual Arousal on Sexual Risk-Taking and Decision-Making in Men and Women.
Skakoon-Sparling Shayna,Cramer Kenneth M,Shuper Paul A
Archives of sexual behavior
Sexual arousal has emerged as an important contextual feature in sexual encounters that can impact safer-sex decision-making. We conducted two experiments that investigated the effects of sexual arousal among male and female participants. Experiment 1 (N = 144) examined the impact of sexual around on sexual health decision-making. Sexually explicit and neutral video clips as well as hypothetical romantic scenarios were used to evaluate the effects of sexual arousal on sexual risk-taking intentions. Men and women who reported higher levels of sexual arousal also displayed greater intentions to participate in risky sexual behavior (e.g., unprotected sex with a new sex partner). Experiment 2 (N = 122) examined the impact of sexual arousal on general risk-taking, using the same videos clips as in Experiment 1 and a modified version of a computerized Blackjack card game. Participants were offered a chance to make either a risky play or a safe play during ambiguous conditions. Increased sexual arousal in Experiment 2 was associated with impulsivity and a greater willingness to make risky plays in the Blackjack game. These findings suggest that, in situations where there are strong sexually visceral cues, both men and women experiencing strong sexual arousal may have lower inhibitions and may experience impaired decision-making. This phenomenon may have an impact during sexual encounters and may contribute to a failure to use appropriate prophylactic protection.
Changes in Male Rat Sexual Behavior and Brain Activity Revealed by Functional Magnetic Resonance Imaging in Response to Chronic Mild Stress.
Chen Guotao,Yang Baibing,Chen Jianhuai,Zhu Leilei,Jiang Hesong,Yu Wen,Zang Fengchao,Chen Yun,Dai Yutian
The journal of sexual medicine
BACKGROUND:Non-organic erectile dysfunction (noED) at functional imaging has been related to abnormal brain activity and requires animal models for further research on the associated molecular mechanisms. AIM:To develop a noED animal model based on chronic mild stress and investigate brain activity changes. METHODS:We used 6 weeks of chronic mild stress to induce depression. The sucrose consumption test was used to assess the hedonic state. The apomorphine test and sexual behavior test were used to select male rats with ED. Rats with depression and ED were considered to have noED. Blood oxygen level-dependent-based resting-state functional magnetic resonance imaging (fMRI) studies were conducted on these rats, and the amplitude of low-frequency fluctuations and functional connectivity were analyzed to determine brain activity changes. OUTCOMES:The sexual behavior test and resting-state fMRI were used for outcome measures. RESULTS:The induction of depression was confirmed by the sucrose consumption test. A low intromission ratio and increased mount and intromission latencies were observed in male rats with depression. No erection was observed in male rats with depression during the apomorphine test. Male rats with depression and ED were considered to have noED. The possible central pathologic mechanism shown by fMRI involved the amygdaloid body, dorsal thalamus, hypothalamus, caudate-putamen, cingulate gyrus, insular cortex, visual cortex, sensory cortex, motor cortex, and cerebellum. Similar findings have been found in humans. CLINICAL TRANSLATION:The present study provided a novel noED rat model for further research on the central mechanism of noED. STRENGTHS AND LIMITATIONS:The present study developed a novel noED rat model and analyzed brain activity changes based at fMRI. The observed brain activity alterations might not extend to humans. CONCLUSION:The present study developed a novel noED rat model with brain activity alterations related to sexual arousal and erection, which will be helpful for further research involving the central mechanism of noED. Chen G, Yang B, Chen J, et al. Changes in Male Rat Sexual Behavior and Brain Activity Revealed by Functional Magnetic Resonance Imaging in Response to Chronic Mild Stress. J Sex Med 2018;15:136-147.
Neuroanatomy and function of human sexual behavior: A neglected or unknown issue?
Calabrò Rocco S,Cacciola Alberto,Bruschetta Daniele,Milardi Demetrio,Quattrini Fabrizio,Sciarrone Francesca,la Rosa Gianluca,Bramanti Placido,Anastasi Giuseppe
Brain and behavior
INTRODUCTION:Sexual desire, arousal, and orgasm are mediated by complex, yet still not fully understood, interactions of the somatic and autonomic nervous systems operating at the central and peripheral levels. Disruption of endocrine, neural, or vascular response, caused by aging, medical illness, neurological diseases, surgery, or drugs, can lead to sexual dysfunctions, thus significantly affecting patients' quality of life. PURPOSE:This narrative review aims at characterizing the involvement of the central nervous system in human sexual behavior. METHODS:A literature search was conducted using PubMed in its entirety up to June 2018, analyzing the studies dealing with the neurobiological and neurophysiological basis of human sexuality. RESULTS:Sexual behavior is regulated by both subcortical structures, such as the hypothalamus, brainstem, and spinal cord, and several cortical brain areas acting as an orchestra to finely adjust this primitive, complex, and versatile behavior. At the central level, dopaminergic and serotonergic systems appear to play a significant role in various factors of sexual response, although adrenergic, cholinergic, and other neuropeptide transmitter systems may contribute as well. CONCLUSIONS:Providing healthcare professionals with information concerning sexual behavior may overcome useless and sometimes dangerous barriers and improve patient management, since sexual well-being is considered one of the most important aspects of one's quality of life.
Dynamics of male sexual arousal: distinct components of brain activation revealed by fMRI.
Ferretti Antonio,Caulo Massimo,Del Gratta Cosimo,Di Matteo Rosalia,Merla Arcangelo,Montorsi Francesco,Pizzella Vittorio,Pompa Paolo,Rigatti Patrizio,Rossini Paolo Maria,Salonia Andrea,Tartaro Armando,Romani Gian Luca
The peripheral mechanisms of male sexual arousal are well known. Recently, neuroimaging techniques, such as PET or fMRI, allowed the investigation of the subjacent cerebral mechanisms. In ten healthy subjects, we have simultaneously recorded fMRI images of brain activation elicited by viewing erotic scenes, and the time course of penile tumescence by means of a custom-built MRI-compatible pneumatic cuff. We have compared activation elicited by video clips with a long duration, that led to sexual arousal and penile erection, and activation elicited by briefly presented still images, that did induce sexual arousal without erection. This comparison and the use of the time course of penile tumescence in video clips allowed to perform a time resolved data analysis and to correlate different patterns of brain activation with different phases of sexual response. The activation maps highlighted a complex neural circuit involved in sexual arousal. Of this circuit, only a few areas (anterior cingulate, insula, amygdala, hypothalamus, and secondary somatosensory cortices) were specifically correlated with penile erection. Finally, these areas showed distinct dynamic relationships with the time course of sexual response. These differences might correspond to different roles in the development and appraisal of the sexual response. These findings shed light on the psychophysiology of male sexuality and open new perspectives for the diagnosis, therapy, and possible rehabilitation of sexual dysfunction.
The role of left superior parietal lobe in male sexual behavior: dynamics of distinct components revealed by FMRI.
Cera Nicoletta,Di Pierro Ezio D,Sepede Gianna,Gambi Francesco,Perrucci Mauro Gianni,Merla Arcangelo,Tartaro Armando,Del Gratta Cosimo,Galatioto Paradiso Giuseppe,Vicentini Carlo,Romani Gian Luca,Ferretti Antonio
The journal of sexual medicine
INTRODUCTION:Despite the interest for the brain correlates of male sexual arousal, few studies investigated neural mechanisms underlying psychogenic erectile dysfunction (ED). Although these studies showed several brain regions active in ED patients during visual erotic stimulation, the dynamics of inhibition of sexual response is still unclear. AIM:This study investigated the dynamics of brain regions involved in the psychogenic ED. METHODS:Functional magnetic resonance imaging (fMRI) and simultaneous penile tumescence (PT) were used to study brain activity evoked in 17 outpatients with psychogenic ED and 19 healthy controls during visual erotic stimulation. Patterns of brain activation related to different phases of sexual response in the two groups were compared. MAIN OUTCOME MEASURES:Simultaneous recording of blood oxygen level-dependent fMRI responses and PT during visual erotic stimulation. RESULTS:During visual erotic stimuli, a larger activation was observed for the patient group in the left superior parietal lobe, ventromedial prefrontal cortex, and posterior cingulate cortex, whereas the control group showed larger activation in the right middle insula and dorsal anterior cingulate cortex and hippocampus. Moreover, the left superior parietal lobe showed a larger activation in patients than controls especially during the later stage of sexual response. CONCLUSION:Our results suggest that, among regions more active in patient group, the left superior parietal lobe plays a crucial role in inhibition of sexual response. Previous studies showed that left superior parietal lobe is involved in monitoring of internal body representation. The larger activation of this region in patients during later stages of sexual response suggests a high monitoring of the internal body representation, possibly affecting the behavioral response. These findings provide insight on brain mechanisms involved in psychogenic ED.
Subcortical BOLD responses during visual sexual stimulation vary as a function of implicit porn associations in women.
Borg Charmaine,de Jong Peter J,Georgiadis Janniko R
Social cognitive and affective neuroscience
Lifetime experiences shape people's attitudes toward sexual stimuli. Visual sexual stimulation (VSS), for instance, may be perceived as pleasurable by some, but as disgusting or ambiguous by others. VSS depicting explicit penile-vaginal penetration (PEN) is relevant in this respect, because the act of penetration is a core sexual activity. In this study, 20 women without sexual complaints participated. We used functional magnetic resonance imaging and a single-target implicit association task to investigate how brain responses to PEN were modulated by the initial associations in memory (PEN-'hot' vs PEN-disgust) with such hardcore pornographic stimuli. Many brain areas responded to PEN in the same way they responded to disgust stimuli, and PEN-induced brain activity was prone to modulation by subjective disgust ratings toward PEN stimuli. The relative implicit PEN-disgust (relative to PEN-'hot') associations exclusively modulated PEN-induced brain responses: comparatively negative (PEN-disgust) implicit associations with pornography predicted the strongest PEN-related responses in the basal forebrain (including nucleus accumbens and bed nucleus of stria terminalis), midbrain and amygdala. Since these areas are often implicated in visual sexual processing, the present findings should be taken as a warning: apparently their involvement may also indicate a negative or ambivalent attitude toward sexual stimuli.
Hypothalamus, sexual arousal and psychosexual identity in human males: a functional magnetic resonance imaging study.
Brunetti M,Babiloni C,Ferretti A,Del Gratta C,Merla A,Olivetti Belardinelli M,Romani G L
The European journal of neuroscience
In a recent functional magnetic resonance imaging study, a complex neural circuit was shown to be involved in human males during sexual arousal [A. Ferretti et al. (2005) Neuroimage, 26, 1086]. At group level, there was a specific correlation between penile erection and activations in anterior cingulate, insula, amygdala, hypothalamus and secondary somatosensory regions. However, it is well known that there are remarkable inter-individual differences in the psychological view and attitude to sex of human males. Therefore, a crucial issue is the relationship among cerebral responses, sexual arousal and psychosexual identity at individual level. To address this issue, 18 healthy male subjects were recruited. Their deep sexual identity (DSI) was assessed following the construct revalidation by M. Olivetti Belardinelli [(1994) Sci. Contrib. Gen. Psychol., 11, 131] of the Franck drawing completion test, a projective test providing, according to this revalidation, quantitative scores on 'accordance/non-accordance' between self-reported and psychological sexual identity. Cerebral activity was evaluated by means of functional magnetic resonance imaging during hard-core erotic movies and sport movies. Results showed a statistically significant positive correlation between the blood oxygen level-dependent signal in bilateral hypothalamus and the Franck drawing completion test score during erotic movies. The higher the blood oxygen level-dependent activation in bilateral hypothalamus, the higher the male DSI profile. These results suggest that, in male subjects, inter-individual differences in the DSI are strongly correlated with blood flow to the bilateral hypothalamus, a dimorphic brain region deeply implicated in instinctual drives including reproduction.
Oxytocinergic modulation of brain activation to cues related to reproduction and attachment: Differences and commonalities during the perception of erotic and fearful social scenes.
Sauer Carina,Montag Christian,Reuter Martin,Kirsch Peter
International journal of psychophysiology : official journal of the International Organization of Psychophysiology
In animal research, the neuropeptide oxytocin (OT) has been known for its role in reproduction and attachment for a longer time. There is strong evidence for an involvement of the mesolimbic dopaminergic system for these effects of OT. In contrast, human research rather concentrated on more human concepts of social cognition and behavior (e.g. trust or processing of fearful faces) and mainly focused on the amygdala as the main neurobiological substrate. To extend this view, we wanted to gain more insight into the neurobiological effects of OT in the context of reproduction and attachment in humans and compare these effects to its well-known effects on fear processing. In a double-blind placebo-controlled fMRI study, we investigated 55 healthy young men using intranasal OT administration. During fMRI, participants saw attachment-related erotic scenes and fearful social scenes. Over all participants, OT had a differential effect on processing of erotic and fearful scenes. While OT administration led to a relative increase of neural activation in mesolimbic structures during processing of erotic stimuli, it decreased amygdala activation for fearful stimuli. On the individual level, we observed significant positive correlations between OT induced activation changes across different brain regions and under different stimulus conditions. Our findings extend the already existing animal literature and provide evidence for a similar involvement of the mesolimbic dopaminergic system for OT effects in the context of reproduction and attachment in humans.
Functional Magnetic Resonance Imaging Detects Between-Group Differences in Neural Activation Among Men with Delayed Orgasm Compared with Normal Controls: Preliminary Report.
Flannigan Ryan,Heier Linda,Voss Henning,Chazen J Levi,Paduch Darius A
The journal of sexual medicine
BACKGROUND:Mechanisms underlying delayed orgasm (DO) are poorly understood; however, known effects of psychotropic medications on sexual function provides a rationale for aberrant central nervous system signaling as a cause. AIM:To compare brain activation between men with normal orgasm and those with lifelong DO during sexual stimulation using brain fMRI algorithms. METHODS:3 subjects with self-reported life-long DO and 6 normal controls were included in this study. The International Index of Erectile Function, Male Sexual Health Questionnaire, and self-reported time to orgasm were used to assess sexual function. Subjects underwent a 3-T fMRI study while viewing 3 video clips: a neutral control (NC), a positive emotional control (EC), and a sexual condition (SC). Each video sequence was repeated 5 times, with 50-second clips presented in a randomized fashion. fMRI data were analyzed in a block design manner to determine areas of differential brain activation between groups. The Allen Brain Atlas of gene expression in the human brain was used to identify signaling pathways in the areas of differential fMRI activation between the DO and control groups. OUTCOMES:The primary outcome was differential activation of fMRI neural activation between groups. RESULTS:Analysis of differential activation in the SC compared with the NC and EC revealed increased activation in the right frontal operculum (P = .003), right prefrontal gyrus (P = .003), and inferior occipital gyrus (P = .003). Increased activation in the right fusiform gyrus of the occipital lobe and the right hippocampus (P = .0004) was seen in the DO group compared with controls. Using the Allen Atlas of Human Brain Expression, we identified corresponding neurotransmitter receptors to this region, including adenosine receptors, muscarinic and nicotinic cholinergic receptors, cannabinoid receptors, and dopamine receptors, among others. CLINICAL IMPLICATIONS:Lifelong DO in men may be due to abnormal neurotransmitter signaling leading to poor progression of arousal due to aberrant processing of sexual cues. Identification of neurotransmitter pathways by fMRI will aid the development of pharmacotherapeutic agents. STRENGTHS & LIMITATIONS:Strengths of this study include the novel application of functional neuroimaging to investigate the pathogenesis of DO. Limitations include the small sample size, making this study exploratory in nature. CONCLUSION:This study revealed differences in brain activation on visualization of sexual stimuli in men with a history of DO compared with controls. Identified regions are rich in numerous neurotransmitter receptor subtypes and may be amenable to pharmacologic targeting to identify novel therapies for these men. Flannigan R, Heier L, Voss H, et al. Functional Magnetic Resonance Imaging Detects Between-Group Differences in Neural Activation Among Men with Delayed Orgasm Compared with Normal Controls: Preliminary Report. J Sex Med 2019:16;1246-1254.
[Brain magnetic resonance imaging in exploring the central neurophysiological mechanisms of penile erection: Progress in studies].
Chen Jian-Huai,Chen Yun
Zhonghua nan ke xue = National journal of andrology
Previous studies have found that penile erection is not only dependent on the peripheral nervous and vascular systems, but also controlled by the central nervous system. Some brain regions are responsible for promoting and suppressing penile erection, respectively. Studies on the brain functions showed both activation and inactivation of the brain regions when receiving sexual stimulation, and those on the brain structure of ED patients revealed atrophy of the gray matter structure and abnormal connection of the white matter fibers. In addition, abnormal connections within emotional, cognitive and default and salience networks were found in patients with psychogenic ED. This article reviews the brain MRI-based studies on the central neurophysiological mechanisms of penile erection, aiming to gain a deeper insight into human neurophysiological mechanisms of the neural circuits controlling erectile function.
Reduced segregation and integration of structural brain network associated with sympathetic and dorsal penile nerve activity in anejaculation patients: a graph-based connectome study.
Chen J,Yang J,Huang X,Ni L,Fan Q,Liu T,Yao Z,Chen Y
INTRODUCTION:Recent neuroimaging studies have indicated that some brain areas are involved in the sexual behavior process. Pre-mature ejaculation patients exhibit altered brain activation and abnormal cortical structures. However, there has been no research evaluating the topological organization of structural brain network in anejaculation (AE). METHODS:We employed diffusion tensor imaging data and graph theory to examine the whole-brain structural networks among 16 AE patients and 23 healthy controls. In addition, the results of sexual function assessment were also obtained from each patient for symptom assessment. Moreover, the relationships between these clinical features and the altered topological characteristics of AE patients were also explored. RESULTS:Decreased clustering coefficient was found in the right amygdala, inferior temporal gyrus, and left pallidum of AE. AE also showed increased path length in the right post-central gyrus, supramarginal gyrus, putamen, pallidum and left heschl gyrus, temporal pole (superior temporal gyrus); however, these altered brain regions showed no significant differences after false discovery rate correction. Moreover, the path length between subcortical and frontal regions was increased in AE. In addition, negative correlations were found between the altered nodal parameters and the amplitudes of somatosensory evoked potentials of dorsal nerve, sympathetic skin response located in the penis. CONCLUSION:Together, our results suggest that AE was associated with disruptions in the topological organization of structural brain networks. The decreased clustering coefficient in temporal and subcortical regions and the increased path length between subcortical and frontal regions may contribute to AE. These findings provide new insights into the pathophysiological mechanisms of AE.
Neuroanatomical correlates of penile erection evoked by photographic stimuli in human males.
Moulier V,Mouras H,Pélégrini-Issac M,Glutron D,Rouxel R,Grandjean B,Bittoun J,Stoléru S
The objective of this study was to identify the cerebral correlates of the early phase, and of low to moderate levels, of penile tumescence using for the first time a volumetric measure of the penile response. We hypothesized that (i) regions whose response had been found correlated with circumferential penile responses in previous studies would be identified with volumetric plethysmography and (ii) that other brain regions, including the amygdalae, would be found using the more sensitive volumetric measurement. In ten healthy males, functional magnetic resonance imaging (fMRI) was used to study brain responses to sexually stimulating photographs and to various categories of control photographs. Both ratings of perceived erection and penile plethysmography demonstrated an erectile response to the presentation of sexually stimulating photographs. Regions where the BOLD signal was correlated with penile volumetric responses included the right medial prefrontal cortex, the right and left orbitofrontal cortices, the insulae, the paracentral lobules, the right ventral lateral thalamic nucleus, the right anterior cingulate cortex and regions involved in motor imagery and motor preparation (supplementary motor areas, left ventral premotor area). This study suggests that the development of low levels of penile tumescence in response to static sexual stimuli is controlled by a network of frontal, parietal, insular and cingulate cortical areas and that penile tumescence reciprocally induces activation in somatosensory regions of the brain.
Molecular mechanisms of penile erection.
Archivos espanoles de urologia
The penis physiological states of flaccidity or erection, result from the contraction or relaxation, respectively, of smooth muscle cells in the corpora cavernosa (CSMCs). They result from the interaction of various inter and intracellular molecular signaling pathways. During the more usual state of flaccidity seems to predominate a tonic sympathetic activity, releasing noradrenaline (NA) and other agonists that generate contractile signals in the CSMCs, with the likely cooperation of endothelium-derived messengers. Through activation of membrane receptors in the CSMCs they raise the intracellular messengers inositol triphosphate (IP3) and diacylglycerol (DAG). This results in a transient increase in cytosolic calcium concentration [Ca2+]i that starts the contractile response which is further sustained by the parallel agonist-induced activation of a "calcium sensitizing" mechanism involving the RhoA/Rho-kinase pathway. Overexpression of the latter might contribute to several vascular disorders as hypertension, vasospasm or erectile dysfunction. On sexual stimulation the cavernous nerves release nitric oxide (NO) that starts the erectile response. They also release acetylcholine that stimulates the endothelium to generate a more sustained release of NO. NO diffuses into CSMCs and increases their intracellular levels of cyclic guanosin monophosphate (cGMP) which decreases [Ca2+]i and deactivates the calcium sensitizing mechanism, thus relaxing CSMCs. This main physiological pathway for CSMCs relaxation is helped by the cyclic adenosin monophosphate (cAMP) pathway activated by various intercellular messengers from neural or paracrine sources, including prostaglandins E (PGE). Different phosphodiesterase enzymes (PDEs) inactivate the cyclic nucleotides thereby limiting their erectogenic action. Indeed the pharmacological inhibition of PDEs, especially the cGMP-specific PDE5, greatly enhances the erectile responses. There are crosstalk mechanisms between the cGMP and cAMP signaling pathways that offer additional possibilities for the pharmacotherapy of erectile dysfunction.
Central Somatosensory Networks Respond to a De Novo Innervated Penis: A Proof of Concept in Three Spina Bifida Patients.
Kortekaas Rudie,Nanetti Luca,Overgoor Max L E,de Jong Bauke M,Georgiadis Janniko R
The journal of sexual medicine
INTRODUCTION:Spina bifida (SB) causes low spinal lesions, and patients often have absent genital sensation and a highly impaired sex life. TOMAX (TO MAX-imize sensation, sexuality and quality of life) is a surgical procedure whereby the penis is newly innervated using a sensory nerve originally targeting the inguinal area. Most TOMAX-treated SB patients initially experience penile stimulation as inguinal sensation, but eventually, the perception shifts to penis sensation with erotic feelings. The brain mechanisms mediating this perceptual shift, which are completely unknown, could hold relevance for understanding the brain's role in sexual development. AIM:The aim of this study was to study how a newly perceived penis would be mapped onto the brain after a lifelong disconnection. METHODS:Three TOMAX-treated SB patients participated in a functional magnetic resonance imagery experiment while glans penis, inguinal area, and index finger were stimulated with a paint brush. MAIN OUTCOME MEASURE:Brush stimulation-induced activation of the primary somatosensory cortex (SI) and functional connectivity between SI and remote cerebral regions. RESULTS:Stimulation of the re-innervated side of the glans penis and the intact contralateral inguinal area activated a very similar location on SI. Yet, connectivity analysis identified distinct SI functional networks. In all three subjects, the middle cingulate cortex (MCC) and the parietal operculum-insular cortex (OIC) were functionally connected to SI activity during glans penis stimulation, but not to SI activity induced by inguinal stimulation. CONCLUSIONS:Investigating central somatosensory network activity to a de novo innervated penis in SB patients is feasible and informative. The consistent involvement of MCC and OIC above and beyond the brain network expected on the basis of inguinal stimulation suggests that these areas mediate the novel penis sensation in these patients. The potential role of MCC and OIC in this process is discussed, along with recommendations for further research.
Neuroanatomy and physiology of ejaculation.
Giuliano François,Clement Pierre
Annual review of sex research
Ejaculation is the final stage of coitus in the mammalian male and results in the expulsion of sperm out of the urethral meatus. Two successive phases, emission and expulsion, can be distinguished during ejaculatory response. Normal anterograde ejaculation requires close coordination of sympathetic, parasympathetic, and somatic components commanding the different peripheral anatomical structures (accessory sexual glands, ducti, and striated muscles) involved in ejaculation. The efferent pathways innervating these anatomical structures drive motor outputs originating from spinal thoracolumbar and lumbosacral nuclei. These spinal ejaculatory centers, the synchronized activation of which is likely carried out by a group of spinal cells, are under the control of both peripheral sensory afferents coming from genital areas and supraspinal information arising from specific brain regions.
Activation and inhibition of the micturition reflex by penile afferents in the cat.
Woock John P,Yoo Paul B,Grill Warren M
American journal of physiology. Regulatory, integrative and comparative physiology
Coordination of the urinary bladder and the external urethral sphincter is controlled by descending projections from the pons and is also subject to modulation by segmental afferents. We quantified the effects on the micturition reflex of sensory inputs from genital afferents traveling in the penile component of the somatic pudendal nerve by electrical stimulation of the dorsal nerve of the penis (DNP) in alpha-chloralose anesthetized male cats. Depending on the frequency of stimulation (range, 1-40 Hz), activation of penile afferents either inhibited contractions of the bladder and promoted urine storage or activated the bladder and produced micturition. Stimulation of the DNP at 5-10 Hz inhibited distension-evoked contractions and increased the maximum bladder capacity before incontinence. Conversely, stimulation at 33 and 40 Hz augmented distension-evoked contractions. When the bladder was filled above a threshold volume (70% of the volume necessary for distension-evoked contractions), stimulation at 20-40 Hz activated de novo the micturition reflex and elicited detrusor contractions that increased voiding efficiency compared with distension-evoked voiding. Electrical stimulation of the DNP with a cuff electrode or percutaneous wire electrode produced similar results. The ability to evoke detrusor contractions by activation of the DNP was preserved following acute spinal cord transection. These results demonstrate a clear role of genital afferents in modulating the micturition reflex and suggest the DNP as a potential target for functional restoration of bladder control using electrical stimulation.
Effects of morphine or naloxone on cocaine-induced genital reflexes in paradoxical sleep-deprived rats.
Andersen M L,Frussa-Filho R,Tufik S
Pharmacology, biochemistry, and behavior
The involvement of opioidergic neurotransmission in the modulation of genital reflexes induced by paradoxical sleep deprivation (PSD) and cocaine in rats was the aim of the present study. Morphine (0, 1, 5 and 10 mg/kg) and naloxone (0, 0.3, 3 and 30 mg/kg) were administered prior to saline or cocaine to rats that had been deprived of sleep and the incidence of penile erections (PE) and ejaculations (EJ) was measured. PSD alone induced PE in 50% and EJ in 20% of the rats, but these behaviors were not influenced by morphine or naloxone. Cocaine potentiated the incidence of genital reflexes in PSD rats to 90% (PE) and 70% (EJ). Morphine and not naloxone significantly reduced the percentage of rats displaying this response at the highest doses. Morphine also significantly reduced PE and EJ frequencies at 10 mg/kg. Furthermore, this inhibitory effect of morphine on genital reflexes was prevented by the prior injection of naloxone. Although a number of factors are involved in such a complex phenomenon as PE and EJ, our data show that activation of the opioidergic systems by the agonist morphine reduces genital reflexes-induced by cocaine in PSD males while the antagonist, naloxone, did not have any significant effect. The findings suggest that the stimulating effects of cocaine in potentiating genital reflexes in PSD rats can be unidirectionally modified by opioidergic systems.
Central regulation of ejaculation.
Coolen Lique M,Allard Julien,Truitt William A,McKenna Kevin E
Physiology & behavior
Ejaculation is a reflex mediated by a spinal control center, referred to as a spinal ejaculation generator. This spinal ejaculation generator coordinates sympathetic, parasympathetic and motor outflow to induce the two phases of ejaculation, i.e., emission and expulsion. In addition, the spinal ejaculation generator integrates this outflow with inputs that are related to the summation of sexual activity prior to ejaculation that are required to trigger ejaculation. Recently, a group of spinothalamic neurons in the lumbar spinal cord (LSt cells) were demonstrated to comprise an integral part of the spinal ejaculation generator. Specifically, lesions of LSt cells completely ablate ejaculatory function. Moreover, LSt cells are activated following ejaculation, but not following other components of sexual behavior. Furthermore, based on their relationship with autonomic nuclei, motoneurons and genital sensory inputs, LSt cells are also in the ideal anatomical position to integrate sensory inputs and autonomic and motor outflow. Additionally, the spinal ejaculation generator is under inhibitory and excitatory influence of supraspinal sites, including the nucleus paragigantocellularis (nPGi), the paraventricular nucleus of the hypothalamus (PVN) and the medial preoptic area (MPOA). Finally, sensory information related to ejaculation is processed in the spinal cord and brain, possibly contributing to the rewarding properties of ejaculation. One candidate pathway for relay of ejaculation-related cues consists of LSt cells and their projections to the parvocellular subparafascicular thalamic nucleus. Moreover, neural activation specifically related to ejaculation is observed in the brain and may reflect of processing of ejaculation-related sensory cues.
The spinal pattern generator for ejaculation.
Carro-Juárez Miguel,Rodríguez-Manzo Gabriela
Brain research reviews
Ejaculation is the physiological process that describes the expulsion of the semen from the urethra. This physiological response is a remarkably sophisticated phenomenon that requires the participation of several stereotyped motor patterns for its expression and when taking place, it starts a constellation of short- and long-lasting physiological and behavioural processes. Little is known about the neural mechanisms accounting for its activation. It has been recently proposed that a central pattern generator located at the spinal level is involved in the control of ejaculation. The aim of this paper is to review the evidence supporting this notion. Thus, the mechanics of ejaculation, its anatomical substrates and innervation are described. Besides, evidence from behavioural, physiological and pharmacological studies that support the existence of an intraspinal rhythm modulating the ejaculatory response are provided. Data are discussed in the context of the physiology of male sexual function.
Temporal pattern of stimulation modulates reflex bladder activation by pudendal nerve stimulation.
McGee Meredith J,Grill Warren M
Neurourology and urodynamics
AIMS:Reflex bladder activation and inhibition by electrical stimulation of pudendal nerve (PN) afferents is a promising approach to restore control of bladder function in persons with lower urinary tract dysfunction caused by disease or injury. The objective of this work was to determine whether bladder activation evoked by pudendal afferent stimulation was dependent on the temporal pattern of stimulation, and whether specific temporal patterns of stimulation produced larger bladder contractions than constant frequency stimulation. METHODS:The mean and maximum contraction pressures evoked by different temporal patterns of stimulation of the dorsal genital branch of the pudendal nerve were measured under isovolumetric conditions in α-chloralose anesthetized cats. A computational model of the spinal neural network mediating the pudendo-vesical reflex was used to understand the mechanisms of different bladder responses to patterned stimulation. RESULTS:The pattern of stimulation significantly affected the magnitude of evoked bladder contractions; several temporal patterns were as effective as regular stimulation, but no pattern evoked larger bladder contractions. Random patterns and patterns with pauses, burst-like activity, or high frequency components evoked significantly smaller bladder contractions, supporting the use of regular frequency stimulation in the development of neural prosthetic approaches for bladder control. CONCLUSIONS:These results reveal that the bladder response to pudendal afferent stimulation is dependent on the pattern, as well as the frequency, of stimulation. The computational model revealed that the effects of patterned pudendal afferent stimulation were determined by the dynamic properties of excitatory and inhibitory interneurons in the lumbosacral spinal cord. Neurourol. Urodynam. 35:882-887, 2016. © 2015 Wiley Periodicals, Inc.
Genital and heart rate response to erotic stimulation in men with and without premature ejaculation.
Rowland D L
International journal of impotence research
This study compared genital and penile response patterns in men with and without premature ejaculation (PE) so as to identify the potential anomalous psychosomatic relationships among men with PE. Genital and heart rate response profiles of 25 men with PE were compared with those of 13 age-matched sexually functional counterparts during visual sexual stimulation presented in combination with vibrotactile penile stimulation. Although no differences were found between men with PE and controls on maximum penile circumference change, overall penile response was significantly lower in the PE group and PE men who ejaculated during the session exhibited shorter latencies to maximum circumference change. Furthermore, significant differences were found between groups in patterns of heart rate. These findings indicate differences in physiological responses between men with PE and sexually functional counterparts during erectile tumescence and progression toward ejaculation. Such differences might be explained by 'premature' sympathetic activation during the sexual response cycle in men with PE, thereby diminishing parasympathetically controlled penile response and triggering sympathetically mediated seminal emission prematurely.
[Anatomy and physiology of sexuality].
Cour F,Droupy S,Faix A,Methorst C,Giuliano F
Progres en urologie : journal de l'Association francaise d'urologie et de la Societe francaise d'urologie
Knowledge of the physiology of male and female sexuality has advanced considerably. Initially there is always desire with its biological neuroendocrine components and its emotional field which is particularly marked in women. There is a distinction between "spontaneous" sexual desire related to intrinsic affective, cognitive stimuli, and fantasies, and "reactive" sexual desire in response to physical arousal. There are similarities between men and women concerning the activation of cerebral zones in sexual arousal contexts in laboratory conditions. The neural pathways for sexual arousal are similar between men and women, bringing into play the sympathetic centres of the thoracic and lumbar spinal cord and, at the sacral level, the parasympathetic center and the motoneurons controlling the muscular contractions of the pelviperineal striated muscles. Genital sensitivity is mainly transmitted by the pudendal nerve in both men and women. Sexual arousal in men consists of penile erection, and ejaculation accompanied with orgasm. In women, sexual arousal causes increase in blood to flow to the vagina leading to lubrication and to the vulva leading to the erection of the clitoris and vulvar hyperaemia. The orgasm which can be multiple in women is accompanied by contractions of the striated perineal muscles. Several neurotransmitters are closely involved in the control of sexuality at the central level: dopamine, ocytocin, serotonin, and peripheral: nitric oxide and noradrenaline in men, vasoactive intestinal peptide and neuropeptide Y in women.
Gender difference in brain activation to audio-visual sexual stimulation; do women and men experience the same level of arousal in response to the same video clip?
Chung W S,Lim S M,Yoo J H,Yoon H
International journal of impotence research
Factors related to sexual arousal are different in men and women. The conditions for women to become aroused are more complex. However, the conventional audio-visual stimulation (AVS) materials used to evaluate sexual arousal are universal. In the present study, we investigated sexual differences in the response to different types of AVS by studying activated areas of the brain using functional magnetic resonance imaging (fMRI). fMRI was performed during two types of AVS in 20 healthy heterosexual volunteers (aged 20-28 years, 10 men and 10 women). The two AVS types were: (1) mood type, erotic video clips with a concrete story and (2) physical type, directly exposing sexual intercourse and genitalia. fMRI images were analyzed and compared for each stimulation with a Mann-Whitney U test, with statistical significance set at P<0.05. Men preferred the physical type of AVS to the mood type (mean arousal score 2.14 vs 1.86 in females) and women preferred the mood type (mean arousal score 2.14 vs 1.86 in males) (P<0.05). Degrees of activation in brain areas differed between genders and types of AVS for each gender. This should be considered when applying the AVS method to evaluate and diagnose female sexual dysfunction.
Male Urogenital System Mapped Onto the Sensory Cortex: Functional Magnetic Resonance Imaging Evidence.
Allen Kachina,Wise Nan,Frangos Eleni,Komisaruk Barry
The journal of sexual medicine
INTRODUCTION:The projection of the human male urogenital system onto the paracentral lobule has not previously been mapped comprehensively. AIM:To map specific urogenital structures onto the primary somatosensory cortex toward a better understanding of sexual response in men. METHODS:Using functional magnetic resonance imaging, we mapped primary somatosensory cortical responses to self-stimulation of the penis shaft, glans, testicles, scrotum, rectum, urethra, prostate, perineum, and nipple. We further compared neural response with erotic and prosaic touch of the penile shaft. MAIN OUTCOME MEASURE:We identified the primary mapping site of urogenital structures on the paracentral lobule and identified networks involved in perceiving touch as erotic. RESULTS:We mapped sites on the primary somatosensory cortex to which components of the urogenital structures project in men. Evidence is provided that penile cutaneous projection is different from deep penile projection. Similar to a prior report in women, we show that the nipple projects to the same somatosensory cortical region as the genitals. Evidence of differential representation of erotic and nonerotic genital self-stimulation is also provided, the former activating sensory networks other than the primary sensory cortex, indicating a role of "top-down" activity in erotic response. CLINICAL IMPLICATIONS:We map primary sites of projection of urogenital structures to the primary somatosensory cortex and differentiate cortical sites of erotic from nonerotic genital self-stimulation. STRENGTH & LIMITATIONS:To our knowledge, this is the first comprehensive mapping onto the primary somatosensory cortex of the projection of the components of the urogenital system in men and the difference in cortical activation in response to erotic vs nonerotic self-stimulation. The nipple was found to project to the same cortical region as the genitals. Evidence is provided that superficial and deep penile stimulation project differentially to the cortex, suggesting that sensory innervation of the penis is provided by more than the (pudendal) dorsal nerve. CONCLUSION:This study reconciles prior apparently conflicting findings and offers a comprehensive mapping of male genital components to the paracentral lobule. We provide evidence of differential projection of light touch vs pressure applied to the penile shaft, suggesting differential innervation of its superficial, vs deep structure. Similar to the response in women, we found nipple projection to genital areas of the paracentral lobule. We also provide evidence of differential representation of erotic and nonerotic genital self-stimulation, the former activating sensory networks other than the primary sensory cortex, indicating a role of top-down activity in erotic response. Allen K, Wise N, Frangos E, et al. Male Urogenital System Mapped Onto the Sensory Cortex: Functional Magnetic Resonance Imaging Evidence. J Sex Med 2020;17:603-613.
How Hot Are They? Neural Correlates of Genital Arousal: An Infrared Thermographic and Functional Magnetic Resonance Imaging Study of Sexual Arousal in Men and Women.
Parada Mayte,Gérard Marina,Larcher Kevin,Dagher Alain,Binik Yitzchak M
The journal of sexual medicine
BACKGROUND:The few studies that have examined the neural correlates of genital arousal have focused on men and are methodologically hard to compare. AIM:To investigate the neural correlates of peripheral physiologic sexual arousal using identical methodology for men and women. METHODS:2 groups (20 men, 20 women) viewed movie clips (erotic, humor) while genital temperature was continuously measured using infrared thermal imaging. Participants also continuously evaluated changes in their subjective arousal and answered discrete questions about liking the movies and wanting sexual stimulation. Brain activity, indicated by blood oxygen level-dependent (BOLD) response, was measured using functional magnetic resonance imaging. OUTCOMES:BOLD responses, genital temperature, and subjective sexual arousal. RESULTS:BOLD activity in a number of brain regions was correlated with changes in genital temperature in men and women; however, activation in women appeared to be more extensive than in men, including the anterior and posterior cingulate cortex, right cerebellum, insula, frontal operculum, and paracingulate gyrus. Examination of the strength of the correlation between BOLD response and genital temperature showed that women had a stronger brain-genital relation compared with men in a number of regions. There were no brain regions in men with stronger brain-genital correlations than in women. CLINICAL TRANSLATION:Our findings shed light on the neurophysiologic processes involved in genital arousal for men and women. Further research examining the specific brain regions that mediate our findings is necessary to pave the way for clinical application. STRENGTHS AND LIMITATIONS:A strength of the study is the use of thermography, which allows for a direct comparison of the neural correlates of genital arousal in men and women. This study has the common limitations of most laboratory-based sexual arousal research, including sampling bias, lack of ecologic validity, and equipment limitations, and those common to neuroimaging research, including BOLD signal interpretation and neuroimaging analysis issues. CONCLUSIONS:Our findings provide direct sex comparisons of the neural correlates of genital arousal in men and women and suggest that brain-genital correlations could be stronger in women. Parada M, Gérard M, Larcher K, et al. How Hot Are They? Neural Correlates of Genital Arousal: An Infrared Thermographic and Functional Magnetic Resonance Imaging Study of Sexual Arousal in Men and Women. J Sex Med 2018;15:217-229.
underlies the evolution of male genital morphology.
Hagen Joanna F D,Mendes Cláudia C,Blogg Amber,Payne Alexander,Tanaka Kentaro M,Gaspar Pedro,Figueras Jimenez Javier,Kittelmann Maike,McGregor Alistair P,Nunes Maria D S
Proceedings of the National Academy of Sciences of the United States of America
Male genital structures are among the most rapidly evolving morphological traits and are often the only features that can distinguish closely related species. This process is thought to be driven by sexual selection and may reinforce species separation. However, while the genetic bases of many phenotypic differences have been identified, we still lack knowledge about the genes underlying evolutionary differences in male genital organs and organ size more generally. The claspers (surstyli) are periphallic structures that play an important role in copulation in insects. Here, we show that divergence in clasper size and bristle number between and is caused by evolutionary changes in (), which encodes a transmembrane leucine-rich repeat domain protein that mediates cell-cell interactions and affinity. There are no fixed amino acid differences in between and , but differences in the expression of this gene in developing genitalia suggest that cis-regulatory changes in underlie the evolution of clasper morphology in these species. Finally, analyses of reciprocal hemizygotes that are genetically identical, except for the species from which the functional allele of originates, determined that the allele of specifies larger claspers with more bristles than the allele of Therefore, we have identified a gene underlying evolutionary change in the size of a male genital organ, which will help to better understand not only the rapid diversification of these structures, but also the regulation and evolution of organ size more broadly.
Anatomy and physiology of genital organs - men.
Clement Pierre,Giuliano François
Handbook of clinical neurology
Male sexual functions involve a number of organs and structures in genitalia whose role is to produce fertilizing gametes and to allow female-partner insemination. The testes belong to the reproductive and endocrine systems as they synthesize spermatozoa and androgens, and are under finely regulated hormonal control by the hypothalamopituitary axis. Sexual responses are controlled by a complex and coordinated interplay of both the somatic and the autonomic nervous system in multiple components of the brain, spinal cord, and relevant peripheral organs. Erectile bodies are an essential element of the penis and engorgement of the penis with blood leads to penile tumescence. Blood engorgement is due to relaxation of smooth-muscle cells of erectile tissue and endothelium of the penile arteries. The penis gains additional rigidity when the ischiocavernosus muscles contract. Stimuli from peripheral and/or central origins activate particular spinal nuclei, causing penile erection. Ejaculation consists of two phases, emission and expulsion, which correspond, respectively, to secretion of the different components of the semen by sex glands and forceful expulsion of semen due to rhythmic contractions of the bulbospongiosus muscle. A spinal generator of ejaculation integrates genital stimuli and sexual cues and, when the excitatory threshold is reached, triggers ejaculation by orchestrating the activation of autonomic and somatic pathways commanding the peripheral events of ejaculation.