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Charles E. Connor; Dynamic integration of object structure information in primate visual cortex. Journal of Vision 2009;9(8):26. doi: 10.1167/9.8.26.
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© ARVO (1962-2015); The Authors (2016-present)
Object perception depends on extensive processing of visual information through multiple stages in the ventral pathway of visual cortex. We use neural recording to study how information about object structure is processed in intermediate and higher-level ventral pathway cortex of macaque monkeys. We find that neurons in area V4 (an intermediate stage) represent object boundary fragments by means of basis function tuning for position, orientation, and curvature. At subsequent stages in posterior, central, and anterior inferotemporal cortex (PIT/CIT/AIT), we find that neurons integrate information about multiple object fragments and their relative spatial configurations. The dynamic nature of this integration process can be observed in the evolution of neural activity patterns across time following stimulus onset. At early time points, neurons are responsive to individual object fragments, and their responses to combined fragments are linearly additive. Over the course of approximately 60 ms, responses to individual object fragments decline and responses to specific fragment combinations increase. This evolution toward nonlinear selectivity for multi-fragment configurations involves both shifts in response properties within neurons and shifts in population activity levels between primarily linear and primarily nonlinear neurons. This pattern is consistent with a simple network model in which the strength of feedforward and recurrent inputs varies continuously across neurons.
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