A Model of the Early Visual System Based on Parallel Spike-Sequence Detection, Showing Orientation Selectivity

Since the first half of the twentieth century, numerous studies have been conducted on how the visual cortex encodes basic image features. One of the hallmarks of basic feature extraction is the phenomenon of orientation selectivity, of which the underlying neuronal-level computational mechanisms remain partially unclear despite being intensively investigated. In this work we present a reduced visual system model (RVSM) of the first level of scene analysis, involving the retina, the lateral geniculate nucleus and the primary visual cortex (V1), showing orientation selectivity. The detection core of the RVSM is the neuromorphic spike-decoding structure MNSD, which is able to learn and recognize parallel spike sequences and considerably resembles the neuronal microcircuits of V1 in both topology and operation. This structure is equipped with plasticity of intrinsic excitability to embed recent findings about V1 operation. The RVSM, which embeds 81 groups of MNSD arranged in 4 oriented columns, is tested using sets of rotated Gabor patches as input. Finally, synthetic visual evoked activity generated by the RVSM is compared with real neurophysiological signal from V1 area: (1) postsynaptic activity of human subjects obtained by magnetoencephalography and (2) spiking activity of macaques obtained by multi-tetrode arrays. The system is implemented using the NEST simulator. The results attest to a good level of resemblance between the model response and real neurophysiological recordings. As the RVSM is available online, and the model parameters can be customized by the user, we propose it as a tool to elucidate the computational mechanisms underlying orientation selectivity.

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Image statistics at the point of gaze during human navigation

Visual Neuroscience ◽

10.1017/s0952523808080978 ◽

2009 ◽

Vol 26 (1) ◽

pp. 81-92 ◽

Cited By ~ 16

Author(s):

CONSTANTIN A. ROTHKOPF ◽

DANA H. BALLARD

Keyword(s):

Visual System ◽

Selection Process ◽

Human Subjects ◽

Image Features ◽

Complex Cells ◽

Cell Responses ◽

Active Selection ◽

Active Nature ◽

Simple And Complex Cells ◽

Distinct Features

AbstractTheories of efficient sensory processing have considered the regularities of image properties due to the structure of the environment in order to explain properties of neuronal representations of the visual world. The regularities imposed on the input to the visual system due to the regularities of the active selection process mediated by the voluntary movements of the eyes have been considered to a much lesser degree. This is surprising, given that the active nature of vision is well established. The present article investigates statistics of image features at the center of gaze of human subjects navigating through a virtual environment and avoiding and approaching different objects. The analysis shows that contrast can be significantly higher or lower at fixation location compared to random locations, depending on whether subjects avoid or approach targets. Similarly, significant differences in the distribution of responses of model simple and complex cells between horizontal and vertical orientations are found over timescales of tens of seconds. By clustering the model simple cell responses, it is established that gaze was directed toward three distinct features of intermediate complexity the vast majority of time. Thus, this study demonstrates and quantifies how the visuomotor tasks of approaching and avoiding objects during navigation determine feature statistics of the input to the visual system through the combined influence on body and eye movements.

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Orientation tuning depends on spatial frequency in mouse visual cortex

10.1101/069997 ◽

2016 ◽

Cited By ~ 1

Author(s):

Inbal Ayzenshtat ◽

Jesse Jackson ◽

Rafael Yuste

Keyword(s):

Visual Cortex ◽

Spatial Frequency ◽

Visual System ◽

Primary Visual Cortex ◽

Receptive Fields ◽

Orientation Selectivity ◽

Natural Scenes ◽

Response Properties ◽

Layer 2 ◽

Mouse Visual Cortex

AbstractThe response properties of neurons to sensory stimuli have been used to identify their receptive fields and functionally map sensory systems. In primary visual cortex, most neurons are selective to a particular orientation and spatial frequency of the visual stimulus. Using two-photon calcium imaging of neuronal populations from the primary visual cortex of mice, we have characterized the response properties of neurons to various orientations and spatial frequencies. Surprisingly, we found that the orientation selectivity of neurons actually depends on the spatial frequency of the stimulus. This dependence can be easily explained if one assumed spatially asymmetric Gabor-type receptive fields. We propose that receptive fields of neurons in layer 2/3 of visual cortex are indeed spatially asymmetric, and that this asymmetry could be used effectively by the visual system to encode natural scenes.Significance StatementIn this manuscript we demonstrate that the orientation selectivity of neurons in primary visual cortex of mouse is highly dependent on the stimulus SF. This dependence is realized quantitatively in a decrease in the selectivity strength of cells in non-optimum SF, and more importantly, it is also evident qualitatively in a shift in the preferred orientation of cells in non-optimum SF. We show that a receptive-field model of a 2D asymmetric Gabor, rather than a symmetric one, can explain this surprising observation. Therefore, we propose that the receptive fields of neurons in layer 2/3 of mouse visual cortex are spatially asymmetric and this asymmetry could be used effectively by the visual system to encode natural scenes.Highlights–Orientation selectivity is dependent on spatial frequency.–Asymmetric Gabor model can explain this dependence.

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Studies of suppression of epileptic seizures with serotonin-modulating anticonsolidation protein (SMAP)

European Psychiatry ◽

10.1016/s0924-9338(11)72612-8 ◽

2011 ◽

Vol 26 (S2) ◽

pp. 907-907

Author(s):

E.N. Panahova ◽

A.A. Mekhtiev

Keyword(s):

Visual Cortex ◽

Visual System ◽

Inhibitory Activity ◽

Basolateral Amygdala ◽

Epileptic Seizures ◽

Positive Component ◽

Interictal Spikes ◽

Inverse Effect ◽

Evoked Activity ◽

The Brain

Earlier studies revealed that tandem of brain amygdala complex and visual system is related directly to development of a number of the brain pathologies. In the present study the model of amygdala epilepsy in rabbits was formed and on its background the evoked activity in the visual cortex, colliculus superior (CS) and retina was analyzed. Tentative studies showed that penicillin-induced epileptic locus in the basolateral amygdala led to sharp (to 200–300%) enhancement of the evoked potentials (EP) in the cortex and retina, whereas in the CS the responses were suppressed significantly. During seizure fit of V-VI stage, according to Racine scale, in the visual cortex, CS and (that is especially interesting) in the retina the regular interictal spikes were fixed. Intramuscular administration (1 mg/kg) of SMAP, purified earlier from rat brain and being in linear relationship with serotonin, into rabbit led to suppression of seizures 30–40 min later. Administration of polyclonal anti-SMAP antibodies into amygdala (10 μl; 1.5 mg/ml) originally induced clear interictal spikes in the visual cortex, CS and retina, while after 30 min inverse effect was observed: elimination of the initial positive component and strong enhancement of the negative phase in the visual cortex. The latter, probably, indicates to switching on compensatory SMAP synthesis after antibody-mediated SMAP inactivation. So, the results indicate to inhibitory activity of SMAP in cessation of epileptic seizures, while its downregulation may bring to seizure initiation.

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Superimposed gratings induce diverse response patterns of gamma oscillations in primary visual cortex

Scientific Reports ◽

10.1038/s41598-021-83923-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Bin Wang ◽

Chuanliang Han ◽

Tian Wang ◽

Weifeng Dai ◽

Yang Li ◽

...

Keyword(s):

Visual Cortex ◽

Primary Visual Cortex ◽

Field Potential ◽

Gamma Oscillations ◽

Neural Mechanisms ◽

Model Parameters ◽

Response Patterns ◽

Region Difference ◽

High Gamma ◽

Spiking Activity

AbstractStimulus-dependence of gamma oscillations (GAMMA, 30–90 Hz) has not been fully understood, but it is important for revealing neural mechanisms and functions of GAMMA. Here, we recorded spiking activity (MUA) and the local field potential (LFP), driven by a variety of plaids (generated by two superimposed gratings orthogonal to each other and with different contrast combinations), in the primary visual cortex of anesthetized cats. We found two distinct narrow-band GAMMAs in the LFPs and a variety of response patterns to plaids. Similar to MUA, most response patterns showed that the second grating suppressed GAMMAs driven by the first one. However, there is only a weak site-by-site correlation between cross-orientation interactions in GAMMAs and those in MUAs. We developed a normalization model that could unify the response patterns of both GAMMAs and MUAs. Interestingly, compared with MUAs, the GAMMAs demonstrated a wider range of model parameters and more diverse response patterns to plaids. Further analysis revealed that normalization parameters for high GAMMA, but not those for low GAMMA, were significantly correlated with the discrepancy of spatial frequency between stimulus and sites’ preferences. Consistent with these findings, normalization parameters and diversity of high GAMMA exhibited a clear transition trend and region difference between area 17 to 18. Our results show that GAMMAs are also regulated in the form of normalization, but that the neural mechanisms for these normalizations might differ from those of spiking activity. Normalizations in different brain signals could be due to interactions of excitation and inhibitions at multiple stages in the visual system.

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Visual Cortex Alterations in Early and Late Blind Subjects During Tactile Perception

Perception ◽

10.1177/0301006621991953 ◽

2021 ◽

Vol 50 (3) ◽

pp. 249-265

Author(s):

A. Ankeeta ◽

S. Senthil Kumaran ◽

Rohit Saxena ◽

Sada N. Dwivedi ◽

Naranamangalam R. Jagannathan

Keyword(s):

Visual Cortex ◽

Children And Adolescents ◽

Age Of Onset ◽

Human Subjects ◽

Functional Results ◽

Blood Oxygen Level Dependent ◽

Tactile Perception ◽

Blood Oxygen Level ◽

Sensory Motor ◽

Post Hoc

Involvement of visual cortex varies during tactile perception tasks in early blind (EB) and late blind (LB) human subjects. This study explored differences in sensory motor networks associated with tactile task in EB and LB subjects and between children and adolescents. A total of 40 EB subjects, 40 LB subjects, and 30 sighted controls were recruited in two subgroups: children (6–12 years) and adolescents (13–19 years). Data were acquired using a 3T MR scanner. Analyses of blood oxygen level dependent (BOLD), functional connectivity (FC), correlation, and post hoc test for multiple comparisons were carried out. Difference in BOLD activity was observed in EB and LB groups in visual cortex during tactile perception, with increased FC of visual with dorsal attention and sensory motor networks in EB. EB adolescents exhibited increased connectivity with default mode and salience networks when compared with LB. Functional results correlated with duration of training, suggestive of better performance in EB. Alteration in sensory and visual networks in EB and LB correlated with duration of tactile training. Age of onset of blindness has an effect in cross-modal reorganization of visual cortex in EB and multimodal in LB in children and adolescents.

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Prediction of Orientation Selectivity from Receptive Field Architecture in Simple Cells of Cat Visual Cortex

Neuron ◽

10.1016/s0896-6273(01)00278-1 ◽

2001 ◽

Vol 30 (1) ◽

pp. 263-274 ◽

Cited By ~ 57

Author(s):

Ilan Lampl ◽

Jeffrey S. Anderson ◽

Deda C. Gillespie ◽

David Ferster

Keyword(s):

Visual Cortex ◽

Receptive Field ◽

Orientation Selectivity ◽

Simple Cells ◽

Cat Visual Cortex

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Man, Monkey, and Blindsight

The Neuroscientist ◽

10.1177/107385849800400410 ◽

1998 ◽

Vol 4 (4) ◽

pp. 227-230 ◽

Cited By ~ 17

Author(s):

Tirin Moore ◽

Hillary R. Rodman ◽

Charles G. Gross

Keyword(s):

Visual Cortex ◽

Visual System ◽

Primary Visual Cortex ◽

Visual Function ◽

Forced Choice ◽

Neural Mechanisms ◽

Residual Vision ◽

Choice Testing

The visual function that survives damage to the primary visual cortex (V1) in humans is often unaccompanied by awareness. This type of residual vision, called “blindsight,” has raised considerable interest because it implies a separation of conscious from unconscious vision mechanisms. The monkey visual system has proven to be a useful model in elucidating the possible neural mechanisms of residual vision and blindsight in humans. Clear similarities, however, between the phenomenology of human and monkey residual vision have only recently become evident. This article summarizes parallels between residual vision in monkeys and humans with damage to V1. These parallels Include the tendency of the remaining vision to require forced-choice testing and the fact that more robust residual vision remains when V1 damage is sustained early in life. NEUROSCIENTIST 4:227–230

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Visual search for object categories is predicted by the representational architecture of high-level visual cortex

Journal of Neurophysiology ◽

10.1152/jn.00569.2016 ◽

2017 ◽

Vol 117 (1) ◽

pp. 388-402 ◽

Cited By ~ 14

Author(s):

Michael A. Cohen ◽

George A. Alvarez ◽

Ken Nakayama ◽

Talia Konkle

Keyword(s):

Visual Cortex ◽

Visual Search ◽

Visual System ◽

Visual Processing ◽

Search Task ◽

Visual Search Task ◽

Visual Object ◽

Neural Responses ◽

Object Categories ◽

High Level

Visual search is a ubiquitous visual behavior, and efficient search is essential for survival. Different cognitive models have explained the speed and accuracy of search based either on the dynamics of attention or on similarity of item representations. Here, we examined the extent to which performance on a visual search task can be predicted from the stable representational architecture of the visual system, independent of attentional dynamics. Participants performed a visual search task with 28 conditions reflecting different pairs of categories (e.g., searching for a face among cars, body among hammers, etc.). The time it took participants to find the target item varied as a function of category combination. In a separate group of participants, we measured the neural responses to these object categories when items were presented in isolation. Using representational similarity analysis, we then examined whether the similarity of neural responses across different subdivisions of the visual system had the requisite structure needed to predict visual search performance. Overall, we found strong brain/behavior correlations across most of the higher-level visual system, including both the ventral and dorsal pathways when considering both macroscale sectors as well as smaller mesoscale regions. These results suggest that visual search for real-world object categories is well predicted by the stable, task-independent architecture of the visual system. NEW & NOTEWORTHY Here, we ask which neural regions have neural response patterns that correlate with behavioral performance in a visual processing task. We found that the representational structure across all of high-level visual cortex has the requisite structure to predict behavior. Furthermore, when directly comparing different neural regions, we found that they all had highly similar category-level representational structures. These results point to a ubiquitous and uniform representational structure in high-level visual cortex underlying visual object processing.

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Emergent orientation selectivity from random networks in mouse visual cortex

10.1101/285197 ◽

2018 ◽

Author(s):

J.J. Pattadkal ◽

G. Mato ◽

C. van Vreeswijk ◽

N. J. Priebe ◽

D. Hansel

Keyword(s):

Visual Cortex ◽

Calcium Imaging ◽

Receptive Fields ◽

Orientation Selectivity ◽

Random Networks ◽

Two Dimensional ◽

V1 Neurons ◽

Mouse Visual Cortex ◽

Whole Cell Recordings ◽

Random Connectivity

SummaryWe study the connectivity principles underlying the emergence of orientation selectivity in primary visual cortex (V1) of mammals lacking an orientation map. We present a computational model in which random connectivity gives rise to orientation selectivity that matches experimental observations. It predicts that mouse V1 neurons should exhibit intricate receptive fields in the two-dimensional frequency domain, causing shift in orientation preferences with spatial frequency. We find evidence for these features in mouse V1 using calcium imaging and intracellular whole cell recordings.

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Transformation from independent to integrative coding of multi-object arrangements in human visual cortex

10.1101/117432 ◽

2017 ◽

Cited By ~ 1

Author(s):

Daniel Kaiser ◽

Marius V. Peelen

Keyword(s):

Visual Cortex ◽

Visual System ◽

Activity Patterns ◽

Spatial Arrangement ◽

Living Room ◽

Natural Scenes ◽

Response Patterns ◽

Object Representations ◽

Individual Object ◽

Object Coding

AbstractTo optimize processing, the human visual system utilizes regularities present in naturalistic visual input. One of these regularities is the relative position of objects in a scene (e.g., a sofa in front of a television), with behavioral research showing that regularly positioned objects are easier to perceive and to remember. Here we use fMRI to test how positional regularities are encoded in the visual system. Participants viewed pairs of objects that formed minimalistic two-object scenes (e.g., a “living room” consisting of a sofa and television) presented in their regularly experienced spatial arrangement or in an irregular arrangement (with interchanged positions). Additionally, single objects were presented centrally and in isolation. Multi-voxel activity patterns evoked by the object pairs were modeled as the average of the response patterns evoked by the two single objects forming the pair. In two experiments, this approximation in object-selective cortex was significantly less accurate for the regularly than the irregularly positioned pairs, indicating integration of individual object representations. More detailed analysis revealed a transition from independent to integrative coding along the posterior-anterior axis of the visual cortex, with the independent component (but not the integrative component) being almost perfectly predicted by object selectivity across the visual hierarchy. These results reveal a transitional stage between individual object and multi-object coding in visual cortex, providing a possible neural correlate of efficient processing of regularly positioned objects in natural scenes.

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