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    Volume and neuron number of the lateral geniculate nucleus in schizophrenia and mood disorders. Dorph-Petersen Karl-Anton,Caric Damira,Saghafi Ramin,Zhang Wei,Sampson Allan R,Lewis David A Acta neuropathologica Subjects with schizophrenia show deficits in visual perception that suggest changes predominantly in the magnocellular pathway and/or the dorsal visual stream important for visiospatial perception. We previously found a substantial 25% reduction in neuron number of the primary visual cortex (Brodmann's area 17, BA17) in postmortem tissue from subjects with schizophrenia. Also, many studies have found reduced volume and neuron number of the pulvinar--the large thalamic association nucleus involved in higher-order visual processing. Here, we investigate if the lateral geniculate nucleus (LGN), the visual relay nucleus of the thalamus, has structural changes in schizophrenia. We used stereological methods based on unbiased principles of sampling (Cavalieri's principle and the optical fractionator) to estimate the total volume and neuron number of the magno- and parovocellular parts of the left LGN in postmortem brains from nine subjects with schizophrenia, seven matched normal comparison subjects and 13 subjects with mood disorders. No significant schizophrenia-related structural differences in volume or neuron number of the left LGN or its major subregions were found, but we did observe a significantly increased total volume of the LGN, and of the parvocellular lamina and interlaminar regions, in the mood group. These findings do not support the hypothesis that subjects with schizophrenia have structural changes in the LGN. Therefore, our previous observation of a schizophrenia-related reduction of the primary visual cortex is probably not secondary to a reduction in the LGN. 10.1007/s00401-008-0410-2
    Topological structure in visual perception. Chen L Science (New York, N.Y.) Three experiments on tachistoscopic perception of visual stimuli demonstrate that the visual system is sensitive to global topological properties. The results indicate that extraction of global topological properties is a basic factor in perceptual organization. 10.1126/science.7134969
    Multidimensional brain activity dictated by winner-take-all mechanisms. Tozzi Arturo,Peters James F Neuroscience letters A novel demon-based architecture is introduced to elucidate brain functions such as pattern recognition during human perception and mental interpretation of visual scenes. Starting from the topological concepts of invariance and persistence, we introduce a Selfridge pandemonium variant of brain activity that takes into account a novel feature, namely, demons that recognize short straight-line segments, curved lines and scene shapes, such as shape interior, density and texture. Low-level representations of objects can be mapped to higher-level views (our mental interpretations): a series of transformations can be gradually applied to a pattern in a visual scene, without affecting its invariant properties. This makes it possible to construct a symbolic multi-dimensional representation of the environment. These representations can be projected continuously to an object that we have seen and continue to see, thanks to the mapping from shapes in our memory to shapes in Euclidean space. Although perceived shapes are 3-dimensional (plus time), the evaluation of shape features (volume, color, contour, closeness, texture, and so on) leads to n-dimensional brain landscapes. Here we discuss the advantages of our parallel, hierarchical model in pattern recognition, computer vision and biological nervous system's evolution. 10.1016/j.neulet.2018.05.014
    The effects of a mid-task break on the brain connectome in healthy participants: A resting-state functional MRI study. Sun Yu,Lim Julian,Dai Zhongxiang,Wong KianFoong,Taya Fumihiko,Chen Yu,Li Junhua,Thakor Nitish,Bezerianos Anastasios NeuroImage Although rest breaks are commonly administered as a countermeasure to reduce mental fatigue and boost cognitive performance, the effects of taking a break on behavior are not consistent. Moreover, our understanding of the underlying neural mechanisms of rest breaks and how they modulate mental fatigue is still rudimentary. In this study, we investigated the effects of receiving a rest break on the topological properties of brain connectivity networks via a two-session experimental paradigm, in which one session comprised four successive blocks of a mentally demanding visual selective attention task (No-rest session), whereas the other contained a rest break between the second and third task blocks (Rest session). Functional brain networks were constructed using resting-state functional MRI data recorded from 20 healthy adults before and after the performance of the task blocks. Behaviorally, subjects displayed robust time-on-task (TOT) declines, as reflected by increasingly slower reaction time as the test progressed and lower post-task self-reported ratings of engagement. However, we did not find a significant effect on task performance due to administering a mid-task break. Compared to pre-task measurements, post-task functional brain networks demonstrated an overall decrease of optimal small-world properties together with lower global efficiency. Specifically, we found TOT-related reduced nodal efficiency in brain regions that mainly resided in the subcortical areas. More interestingly, a significant block-by-session interaction was revealed in local efficiency, attributing to a significant post-task decline in No-rest session and a preserved local efficiency when a mid-task break opportunity was introduced in the Rest session. Taken together, these findings augment our understanding of how the resting brain reorganizes following the accumulation of prolonged task, suggest dissociable processes between the neural mechanisms of fatigue and recovery, and provide some of the first quantitative insights into the cognitive neuroscience of work and rest. 10.1016/j.neuroimage.2017.02.084
    Different levels of visual perceptual skills are associated with specific modifications in functional connectivity and global efficiency. Danti Sabrina,Handjaras Giacomo,Cecchetti Luca,Beuzeron-Mangina Helen,Pietrini Pietro,Ricciardi Emiliano International journal of psychophysiology : official journal of the International Organization of Psychophysiology The disembedding ability (i.e., the ability to identify a simple masked figure within a complex one) depends on attentional mechanisms, executive functions and working memory. Recent cognitive models ascribed different levels of disembedding task performance to the efficiency of the subtended mental processes engaged during visuo-spatial perception. Here we aimed at assessing whether different levels of the disembedding ability were associated to the functional signatures of neural efficiency, defined as a specific modulation in response magnitude and functional connectivity strength in task-related areas. Consequently, brain activity evoked by a visual task involving the disembedding ability was acquired using functional magnetic resonance imaging (fMRI) in a sample of 23 right-handed healthy individuals. Brain activity was analyzed at different levels of information processing, from local responses to connectivity interactions between brain nodes, as far as to network topological properties. All different levels of information processing were significantly modulated by individual behavioral performance. Specifically, single voxel response magnitude, connectivity strength of the right intrahemispheric and interhemispheric edges, and graph measures (i.e., local and global efficiency) were negatively associated to behavioral performance. Altogether, these results indicate that efficiency during a disembedding task cannot be merely attributed to a reduced neural recruitment of task-specific regions, but can be better characterized as an enhanced functional hemispherical asymmetry. 10.1016/j.ijpsycho.2017.10.002
    What determines the object-level visual masking: The bottom-up role of topological change. Huang Yan,He Lixia,Wang Wenbo,Meng Qianli,Zhou Tiangang,Chen Lin Journal of vision Object substitution masking (OSM) is said to occur on an object level without a close spatiotemporal proximity of target and mask. An influential account for OSM is "object updating," which espouses that OSM occurs when the target is updated by the mask as they share a single object representation. However, it is unclear what attribute determines whether the mask shares the same object representation as the target. We hypothesize that topological property determines whether a new object representation is built, and hence topological perception modulates object-level masking. We systematically manipulated the similarity between the target and the mask by changing a topological property (number of holes), color, shape, and orientation. We found that the topological change between the target and the mask reduced masking effects of all the other properties. Changing color, shape, or orientation, however, did not affect the masking effect of any other property. The global effect of the topological change remained across a variety of temporal and spatial distances between the target and the mask and was not limited to masking paradigms. Thus, our results suggest that the object representation, constrained by its topological properties, serves as a higher and global level of OSM, influencing the ongoing visual processing of features that are at a lower and local level. 10.1167/18.1.3
    Visual working memory representation as a topological defined perceptual object. Wei Ning,Zhou Tiangang,Zhang Zihao,Zhuo Yan,Chen Lin Journal of vision The question of what the basic unit is of visual working memory remains one of the most fundamental and controversial issues. In the current study, we proposed a unique perspective based on early topological perception to describe the nature of representation in visual working memory. In a series of updating change-detection tasks, the repetition-benefit effect on color memory was not affected when items in the second memory array underwent massive changes of nontopological features from the first memory array. However, when the topological properties of an item changed, the repetition-benefit effect was destroyed, suggesting that the item was perceived as a new object impairing the original memory. Hence, our results suggest that a perceptual object defined by its topological invariance might be a unique perspective from which to describe representations of visual working memory. 10.1167/19.7.12
    A Neural Network Model With Gap Junction for Topological Detection. Wang Chaoming,Lian Risheng,Dong Xingsi,Mi Yuanyuan,Wu Si Frontiers in computational neuroscience Visual information processing in the brain goes from global to local. A large volume of experimental studies has suggested that among global features, the brain perceives the topological information of an image first. Here, we propose a neural network model to elucidate the underlying computational mechanism. The model consists of two parts. The first part is a neural network in which neurons are coupled through gap junctions, mimicking the neural circuit formed by alpha ganglion cells in the retina. Gap junction plays a key role in the model, which, on one hand, facilitates the synchronized firing of a neuron group covering a connected region of an image, and on the other hand, staggers the firing moments of different neuron groups covering disconnected regions of the image. These two properties endow the network with the capacity of detecting the connectivity and closure of images. The second part of the model is a read-out neuron, which reads out the topological information that has been converted into the number of synchronized firings in the retina network. Our model provides a simple yet effective mechanism for the neural system to detect the topological information of images in ultra-speed. 10.3389/fncom.2020.571982
    Topological dominance in peripheral vision. Wu Ruijie,Wang Bo,Zhuo Yan,Chen Lin Journal of vision The question of what peripheral vision is good for, especially in pattern recognition, is one of the most important and controversial issues in cognitive science. In a series of experiments, we provide substantial evidence that observers' behavioral performance in the periphery is consistently superior to central vision for topological change detection, while nontopological change detection deteriorates with increasing eccentricity. These experiments generalize the topological account of object perception in the periphery to different kinds of topological changes (i.e., including introduction, disappearance, and change in number of holes) in comparison with a broad spectrum of geometric properties (e.g., luminance, similarity, spatial frequency, perimeter, and shape of the contour). Moreover, when the stimuli were scaled according to cortical magnification factor and the task difficulty was well controlled by adjusting luminance of the background, the advantage of topological change detection in the periphery remained. The observed advantage of topological change detection in the periphery supports the view that the topological definition of objects provides a coherent account for object perception in peripheral vision, allowing pattern recognition with limited acuity. 10.1167/jov.21.10.19
    Behavior-dependent directional tuning in the human visual-navigation network. Nau Matthias,Navarro Schröder Tobias,Frey Markus,Doeller Christian F Nature communications The brain derives cognitive maps from sensory experience that guide memory formation and behavior. Despite extensive efforts, it still remains unclear how the underlying population activity unfolds during spatial navigation and how it relates to memory performance. To examine these processes, we combined 7T-fMRI with a kernel-based encoding model of virtual navigation to map world-centered directional tuning across the human cortex. First, we present an in-depth analysis of directional tuning in visual, retrosplenial, parahippocampal and medial temporal cortices. Second, we show that tuning strength, width and topology of this directional code during memory-guided navigation depend on successful encoding of the environment. Finally, we show that participants' locomotory state influences this tuning in sensory and mnemonic regions such as the hippocampus. We demonstrate a direct link between neural population tuning and human cognition, where high-level memory processing interacts with network-wide visuospatial coding in the service of behavior. 10.1038/s41467-020-17000-2
    Late Development of Early Visual Perception: No Topology-Priority in Peripheral Vision Until Age 10. Tang Hongsi,Song Rujiao,Hu Yueyan,Tian Yixin,Lu Zhonghua,Chen Lin,Huang Yan Child development Topological property (TP) is a basic geometric attribute of objects, which is preserved over continuous and one-to-one transformations and considered to be processed in early vision. This study investigated the global TP perception of 773 children aged 6-14, as compared to 179 adults. The results revealed that adults and children aged 10 or over show a TP priority trend in both central and peripheral vision, that is, less time is required to discriminate TP differences than non-TP differences. Children aged 6-8 show a TP priority trend for central stimuli, but not in their peripheral vision. The TP priority effect in peripheral vision does not emerge until age ˜10 years, and the development of central and peripheral vision seems to be different. 10.1111/cdev.13629
    Semi-Supervised Perception Augmentation for Aerial Photo Topologies Understanding. Zhang Luming,Pan Zhigeng,Shao Ling IEEE transactions on image processing : a publication of the IEEE Signal Processing Society Intelligently understanding the sophisticated topological structures from aerial photographs is a useful technique in aerial image analysis. Conventional methods cannot fulfill this task due to the following challenges: 1) the topology number of an aerial photo increases exponentially with the topology size, which requires a fine-grained visual descriptor to discriminatively represent each topology; 2) identifying visually/semantically salient topologies within each aerial photo in a weakly-labeled context, owing to the unaffordable human resources required for pixel-level annotation; and 3) designing a cross-domain knowledge transferal module to augment aerial photo perception, since multi-resolution aerial photos are taken asynchronistically in practice. To handle the above problems, we propose a unified framework to understand aerial photo topologies, focusing on representing each aerial photo by a set of visually/semantically salient topologies based on human visual perception and further employing them for visual categorization. Specifically, we first extract multiple atomic regions from each aerial photo, and thereby graphlets are built to capture the each aerial photo topologically. Then, a weakly-supervised ranking algorithm selects a few semantically salient graphlets by seamlessly encoding multiple image-level attributes. Toward a visualizable and perception-aware framework, we construct gaze shifting path (GSP) by linking the top-ranking graphlets. Finally, we derive the deep GSP representation, and formulate a semi-supervised and cross-domain SVM to partition each aerial photo into multiple categories. The SVM utilizes the global composition from low-resolution counterparts to enhance the deep GSP features from high-resolution aerial photos which are partially-annotated. Extensive visualization results and categorization performance comparisons have demonstrated the competitiveness of our approach. 10.1109/TIP.2021.3079820