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Sunday, July 19 • 7:00pm - 8:00pm
P175: Analytic Model for Feature Maps in the Primary Visual Cortex

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Xiaochen Liu, Peter Robinson

This study proposes a compact analytic model that describes the orientation preference (OP) and ocular dominance (OD) maps of the primary visual cortex (V1) in hypercolumns, within which OP and OD are arranged as pinwheels and stripes. This model consists of two parts: (i) an OP operator, which uses a linear combination of weighted partial derivatives to incorporate the small- scale local neuron sensitivity to the preferred orientation of the visual inputs; and (ii) a receptive field (RF) operator, which models the spatial RF structure of V1 simple cell, and it is derived from finding the neural activities at arbitrary location with a directional anisotropic modulation of projections from neighboring neurons at scales of a few tenths of a millimetre. The parameters of the proposed OP-OD map model are tuned to maximize the neural response at the desired OP, by matching the width of OP tuning curves with experimental results. Moreover, we find that the weights of the partial derivatives in OP operator do not significantly affect the OP selectivity of the neuron, whereas the overall envelope of the RF operator does. This agrees with Hubel and Wiesel’s prediction [1], that orientation tuning width of V1 simple cell is related to the elongation of its RF.

The simplified OP-OD map is used to provide inputs to neural field theory (NFT) analysis of the approximate periodic OP-OD structure of V1. This is done by decomposing the OP-OD map representation in Fourier domain to generate a sparse set of Fourier coefficients. In addition, only the least number of coefficients, which are enough to preserves the basic spatial arrangement of OP-OD map, are passed to NFT for investigating OP map related neural activities. The decomposition is also applied on more realistic OP maps generated from published models and its properties are discussed.

1. Hubel, D.H. and Wiesel, T.N. Receptive fields, binocular interaction and functional architecture in the cat’s visual cortex. J Physiol. 1962,160(1): 106-154.

Speakers
XL

Xiaochen Liu

SCHOOL OF PHYSICS, University of Sydney, Australia



Sunday July 19, 2020 7:00pm - 8:00pm CEST
Slot 17