Vision is an essential part of our well-being. Yet, the neural mechanisms allowing for the stable perception of visual objects under variations in their position are not sufficiently understood. In particular, we currently lack specific knowledge of how neural responses are transformed in the ventral visual pathway where visual object recognition is performed. Here we propose to probe neurons in visual areas V2 and V4 within the ventral pathway with natural stimuli in order to systematically determine their stimulus selectivity preferences. Natural stimuli offer a systematic way to study neural feature selectivity because they elicit robust responses from neurons at all stages of visual processing and because they constitute a stimulus set that is not tied to a particular hypothesis about prevalent neural feature selectivity. We have recently developed statistical methods that allow the characterization of the feature selectivity of neurons that are probed with natural stimuli, and which take into account nonlinear aspects of neural responses. Extending these methods to account for the fact that the responses of neurons in extrastriate visual areas can be tolerant to shifts in stimulus position (aim 1) will allow the systematic characterization of the stimulus preferences of these neurons under natural conditions. Responses of each neuron will be characterized according to the two localized stimulus features that are most relevant for the neural responses. This will provide a direct measure of the selectivity to curved elements in visual scenes thought to occur in V4 responses (aim 2). Finally, we will test whether specific parameters of neural feature selectivity, such as orientation and curvature, determines the directions of increased tolerance to shifts in object position (aim 3). Understanding the neural mechanisms of shape perception in the healthy nervous system is a key element in developing effective therapies for neurological disorders, such as apperceptive agnosia, where visual object recognition is impaired.

Public Health Relevance

This study will elucidate the neural mechanisms responsible for shape perception. These neural processes are disrupted in several neurological disorders affecting vision. Understanding the neural mechanisms of shape perception in the healthy nervous system is a key element of developing effective therapies for neurological disorders where visual object recognition is impaired.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY019493-04
Application #
8311749
Study Section
Central Visual Processing Study Section (CVP)
Program Officer
Steinmetz, Michael A
Project Start
2009-09-01
Project End
2014-07-31
Budget Start
2012-08-01
Budget End
2013-07-31
Support Year
4
Fiscal Year
2012
Total Cost
$450,014
Indirect Cost
$212,414
Name
Salk Institute for Biological Studies
Department
Type
DUNS #
078731668
City
La Jolla
State
CA
Country
United States
Zip Code
92037
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Sharpee, Tatyana O; Calhoun, Adam J; Chalasani, Sreekanth H (2014) Information theory of adaptation in neurons, behavior, and mood. Curr Opin Neurobiol 25:47-53
Sharpee, Tatyana O (2013) Computational identification of receptive fields. Annu Rev Neurosci 36:103-20
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Aljadeff, Johnatan; Segev, Ronen; Berry 2nd, Michael J et al. (2013) Spike triggered covariance in strongly correlated gaussian stimuli. PLoS Comput Biol 9:e1003206
Saremi, Saeed; Sejnowski, Terrence J; Sharpee, Tatyana O (2013) Double-gabor filters are independent components of small translation-invariant image patches. Neural Comput 25:922-39
Kaardal, Joel; Fitzgerald, Jeffrey D; Berry 2nd, Michael J et al. (2013) Identifying functional bases for multidimensional neural computations. Neural Comput 25:1870-90
Sharpee, Tatyana O; Kouh, Minjoon; Reynolds, John H (2013) Trade-off between curvature tuning and position invariance in visual area V4. Proc Natl Acad Sci U S A 110:11618-23

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