The marginal phase in a two-dimensional mean-field model of the primary visual cortex
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1
Leibniz University Hannover, Germany
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2
BCCN Berlin, Germany
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3
Technical University Berlin, Germany
We study a two-dimensional mean-field model of orientation-selective neurons in the primary visual cortex (V1). The main question addressed in this work is whether the system is able to operate in the marginal phase, a parameter regime that, in one-dimensional ring models, has been shown to reproduce the experimental finding of contrast-invariant orientation tuning by a symmetry-breaking mechanism. Our model is based on a spatially isotropic network that receives afferent, pinwheel-structured input from the lateral geniculate nucleus (LGN). The work shows that the two-dimensional model possesses an operating regime that behaves as a two-dimensional analogue of the marginal phase. By a symmetry-breaking mechanism, even weakly tuned LGN inputs generate localized and sharply tuned activity bumps. The input determines the location of the bumps and their amplitude. Their width, however, only depends on the network connectivity. Orientation tuning is sharp and contrast-invariant. Thus, the transition from one to two dimensions, necessary to capture the pinwheel architecture of orientation maps, does not affect the system's ability to work in the marginal phase. Interestingly, in this operating regime, orientation tuning maps do not necessarily reflect the spatial organization of the afferent LGN input, but may exhibit new pinwheel-singularities.
Conference:
Bernstein Symposium 2008, Munich, Germany, 8 Oct - 10 Oct, 2008.
Presentation Type:
Poster Presentation
Topic:
All Abstracts
Citation:
Dietzsch
T,
Stimberg
M,
Wimmer
K and
Obermayer
K
(2008). The marginal phase in a two-dimensional mean-field model of the primary visual cortex.
Front. Comput. Neurosci.
Conference Abstract:
Bernstein Symposium 2008.
doi: 10.3389/conf.neuro.10.2008.01.040
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Received:
13 Nov 2008;
Published Online:
13 Nov 2008.
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Correspondence:
Thorsten Dietzsch, Leibniz University Hannover, Hannover, Germany, thorsten.dietzsch@gmx.de