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Neural Information ProcessingComputational Models of Primary Visual Cortex

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Computational Models of Primary Visual Cortex

Lupe

Primary visual cortex in higher animals like cats and non-human primates is one of the best characterized cortical areas. Therefore, it serves as a paradigmatic area for understanding visual processing and for understanding cortical computation in general. Here we use computational approaches, which are based on network models of different complexity (rate models vs. spiking models, integrate-and-fire vs. Hodgkin-Huxley models, columnar models vs. map models), in order to characterize the functional organization of visual cortex, to study the dynamics of the cortical network, and to evaluate hypotheses about the mechanisms shaping the response properties of visual cortical neurons. A recent model-based analysis of experimental data provided evidence, that cortical networks may operate in a regime which is close to the transition to self-sustained firing. This finding will serve as one starting point for further investigations.

Acknowledgement: Research was funded by BMBF, DFG, HFSPO, Welcome Trust and the Technische Universität Berlin.

Selected Publications:

Geometry of Orientation and Ocular Dominance Columns in Monkey Striate Cortex
Citation key Obermayer1993a
Author Obermayer, K. and Blasdel, G.G.
Pages 4114 – 4129
Year 1993
Journal Journal of Neuroscience
Volume 13
Abstract In addition to showing that ocular dominance is organized in slabs and that orientation preferences are organized in linear sequences likely to reflect slabs, Hubel and Wiesel (1974a) discussed the intriguing possibility that slabs of orientation might intersect slabs of ocular dominance at some consistent angle. Advances in optical imaging now make it possible to test this possibility directly. When maps of orientation are analyzed quantitatively, they appear to arise from a combination of at least two competing themes: one where orientation preferences change linearly along straight axes, remaining constant along perpendicular axes and forming iso-orientation slabs along the way, and one where orientation preferences change continuously along circular axes, remaining constant along radial axes and forming singularities at the centers of the spaces enclosed. When orientation patterns are compared with ocular dominance patterns from the same cortical regions, quantitative measures reveal (1) that singularities tend to lie at the centers of ocular dominance columns, (2) that linear zones (arising where orientation preferences change along straight axes) tend to lie at the edges of ocular dominance columns, and (3) that the short iso-orientation bands within each linear zone tend to intersect the borders of ocular dominance slabs at angles of approximately 90 degrees.
Bibtex Type of Publication Selected:v1
Link to original publication Download Bibtex entry

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