scholarly journals Unconscious Number Discrimination in the Human Visual System

2020 ◽  
Vol 30 (11) ◽  
pp. 5821-5829 ◽  
Author(s):  
Ché Lucero ◽  
Geoffrey Brookshire ◽  
Clara Sava-Segal ◽  
Roberto Bottini ◽  
Susan Goldin-Meadow ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Sensory Modality ◽  
Occipital Lobe ◽  
Spectral Amplitude ◽  
Intraparietal Sulcus ◽  
Backward Masking ◽  
Number Discrimination ◽  
Number Representations ◽  
Influential Theory

Abstract How do humans compute approximate number? According to one influential theory, approximate number representations arise in the intraparietal sulcus and are amodal, meaning that they arise independent of any sensory modality. Alternatively, approximate number may be computed initially within sensory systems. Here we tested for sensitivity to approximate number in the visual system using steady state visual evoked potentials. We recorded electroencephalography from humans while they viewed dotclouds presented at 30 Hz, which alternated in numerosity (ranging from 10 to 20 dots) at 15 Hz. At this rate, each dotcloud backward masked the previous dotcloud, disrupting top-down feedback to visual cortex and preventing conscious awareness of the dotclouds’ numerosities. Spectral amplitude at 15 Hz measured over the occipital lobe (Oz) correlated positively with the numerical ratio of the stimuli, even when nonnumerical stimulus attributes were controlled, indicating that subjects’ visual systems were differentiating dotclouds on the basis of their numerical ratios. Crucially, subjects were unable to discriminate the numerosities of the dotclouds consciously, indicating the backward masking of the stimuli disrupted reentrant feedback to visual cortex. Approximate number appears to be computed within the visual system, independently of higher-order areas, such as the intraparietal sulcus.

Man, Monkey, and Blindsight

1998 ◽  
Vol 4 (4) ◽  
pp. 227-230 ◽  
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

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

2017 ◽  
Vol 117 (1) ◽  
pp. 388-402 ◽  
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.

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

2017 ◽  
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.

scholarly journals Unique spatial integration in mouse primary visual cortex and higher visual areas

2019 ◽  
Author(s):  
Kevin A. Murgas ◽  
Ashley M. Wilson ◽  
Valerie Michael ◽  
Lindsey L. Glickfeld
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Primary Visual Cortex ◽  
Spatial Information ◽  
Spatial Scales ◽  
Spatial Integration ◽  
Global Features ◽  
Wide Range ◽  
Visual Areas ◽  
Higher Visual Areas

AbstractNeurons in the visual system integrate over a wide range of spatial scales. This diversity is thought to enable both local and global computations. To understand how spatial information is encoded across the mouse visual system, we use two-photon imaging to measure receptive fields in primary visual cortex (V1) and three downstream higher visual areas (HVAs): LM (lateromedial), AL (anterolateral) and PM (posteromedial). We find significantly larger receptive field sizes and less surround suppression in PM than in V1 or the other HVAs. Unlike other visual features studied in this system, specialization of spatial integration in PM cannot be explained by specific projections from V1 to the HVAs. Instead, our data suggests that distinct connectivity within PM may support the area’s unique ability to encode global features of the visual scene, whereas V1, LM and AL may be more specialized for processing local features.

scholarly journals Using perceptual tasks to selectively measure magnocellular and parvocellular performance: Rationale and a user’s guide

2021 ◽  
Author(s):  
Mark Edwards ◽  
Stephanie C. Goodhew ◽  
David R. Badcock
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Lateral Geniculate Nucleus ◽  
Cognitive Functions ◽  
Visual Information ◽  
Visual Stimuli ◽  
Visual Scene ◽  
Ongoing Debate ◽  
Parvocellular Pathway ◽  
Lesion Studies

AbstractThe visual system uses parallel pathways to process information. However, an ongoing debate centers on the extent to which the pathways from the retina, via the Lateral Geniculate nucleus to the visual cortex, process distinct aspects of the visual scene and, if they do, can stimuli in the laboratory be used to selectively drive them. These questions are important for a number of reasons, including that some pathologies are thought to be associated with impaired functioning of one of these pathways and certain cognitive functions have been preferentially linked to specific pathways. Here we examine the two main pathways that have been the focus of this debate: the magnocellular and parvocellular pathways. Specifically, we review the results of electrophysiological and lesion studies that have investigated their properties and conclude that while there is substantial overlap in the type of information that they process, it is possible to identify aspects of visual information that are predominantly processed by either the magnocellular or parvocellular pathway. We then discuss the types of visual stimuli that can be used to preferentially drive these pathways.

scholarly journals Cortical reorganization of the visual system in post-stroke hemianopia studied with fMRI

Stroke ◽  
2001 ◽  
Vol 32 (suppl_1) ◽  
pp. 334-334
Author(s):  
Gereon Nelles ◽  
Guido Widmann ◽  
Joachim Esser ◽  
Anette Meistrowitz ◽  
Johannes Weber ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Visual System ◽  
Primary Visual Cortex ◽  
Visual Stimuli ◽  
Checkerboard Pattern ◽  
Partial Recovery ◽  
Area 18 ◽  
Area 19 ◽  
Stimulation Of

102 Introduction: Restitution of unilateral visual field defects following occipital cortex lesions occurs rarely. Partial recovery, however, can be observed in patients with incomplete lesion of the visual cortex. Our objective was to study the neuroplastic changes in the visual system that underlie such recovery. Methods and Results: Six patients with a left PCA-territory cortical stroke and 6 healthy control subjects were studied during rest and during visual stimulation using a 1.5 T fMRI with a 40 mT gradient. Visual stimuli were projected with a laptop computer onto a 154 x 115 cm screen, placed 90 cm in front of the gantry. Subjects were asked to fixate a red point in the center of the screen during both conditions. During stimulation, a black-and-white checkerboard pattern reversal was presented in each hemifield. For each side, 120 volumes of 48 contiguous axial fMRI images were obtained during rest and during hemifield stimulation in alternating order (60 volumes for each condition). Significant differences of rCBF between stimulation and rest were assessed as group analyses using statistical parametric mapping (SPM 99; p<0.01, corrected for multiple comparison). In controls, strong increases of rCBF (Z=7.6) occurred in the contralateral primary visual cortex V1 (area 17) and in V3a (area 18) and V5 (area 19). No differences were found between the right and left side in controls. During stimulation of the unaffected (left) visual field in hemianopic patients, activation occurred in contralateral V1, but the strongest increases of rCBF (Z>10) were seen in contralateral V3a (area 18) and V5 (area 19). During stimulation of the hemianopic (right) visual field, no activation was found in the primary visual cortex of either hemisphere. The most significant activation (Z=9.2) was seen in the ipsilateral V3a and V5 areas, and contralateral (left) V3a. Conclusions: Partial recovery from hemianopia is associated with strong ipsilateral activation of the visual system. Processing of visual stimuli in the hemianopic side spares the primary visual cortex and may involve recruitment of neurons in ipsilateral (contralesional) areas V3a and V5.

The Insect Visual System: Correspondence with Vertebrates and with Olfactory Processing

2017 ◽  
pp. 293-306
Author(s):  
Nicholas J. Strausfeld
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Nobel Prize ◽  
Insect Visual System ◽  
Dendritic Trees ◽  
Optic Lobes ◽  
Visual Systems ◽  
Valid Comparison ◽  
Olfactory Processing ◽  
Lateral Protocerebrum

A 1915 monograph by the Nobel Prize–winning neuroanatomist Santiago Ramón y Cajal and Domingo Sánchez y Sánchez, describing neurons and their organization in the optic lobes of insects, is now standard fare for those studying the microcircuitry of the insect visual system. The work contains prescient assumptions about possible functional arrangements, such as lateral interactions, centrifugal pathways, and the convergence of neurons onto wider dendritic trees, to provide central integration of information processed at peripheral levels of the system. This chapter will consider further indications of correspondence between the insect-crustacean and the vertebrate visual systems, with particular reference to the deep organization of the optic lobe’s third optic neuropil, the lobula, and part of the lateral forebrain (protocerebrum) that receives inputs from it. Together, the lobula and lateral protocerebrum suggest valid comparison with the visual cortex and olfactory centers.

scholarly journals Number detectors spontaneously emerge in a deep neural network designed for visual object recognition

2019 ◽  
Vol 5 (5) ◽  
pp. eaav7903 ◽  
Author(s):  
Khaled Nasr ◽  
Pooja Viswanathan ◽  
Andreas Nieder
Keyword(s):  
Neural Network ◽  
Object Recognition ◽  
Visual System ◽  
Deep Neural Network ◽  
Number Sense ◽  
Discrimination Performance ◽  
Visual Object ◽  
Visual Object Recognition ◽  
Biologically Inspired ◽  
Number Discrimination

Humans and animals have a “number sense,” an innate capability to intuitively assess the number of visual items in a set, its numerosity. This capability implies that mechanisms to extract numerosity indwell the brain’s visual system, which is primarily concerned with visual object recognition. Here, we show that network units tuned to abstract numerosity, and therefore reminiscent of real number neurons, spontaneously emerge in a biologically inspired deep neural network that was merely trained on visual object recognition. These numerosity-tuned units underlay the network’s number discrimination performance that showed all the characteristics of human and animal number discriminations as predicted by the Weber-Fechner law. These findings explain the spontaneous emergence of the number sense based on mechanisms inherent to the visual system.

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