The influence of cortical feature maps on the encoding of the orientation of a short line |
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Authors: | K N Shokhirev T Kumar D A Glaser |
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Institution: | (1) Department of Physics, University of California, Berkeley, CA 94720-3206, USA;(2) Department of Molecular and Cell Biology, Division of Neurobiology, University of California, Berkeley |
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Abstract: | The inhomogeneous distribution of the receptive fields of cortical neurons influences the cortical representation of the orientation
of short lines seen in visual images. We construct a model of the response of populations of neurons in the human primary
visual cortex by combining realistic response properties of individual neurons and cortical maps of orientation and location
preferences. The encoding error, which characterizes the difference between the parameters of a visual stimulus and their
cortical representation, is calculated using Fisher information as the square root of the variance of a statistically efficient
estimator. The error of encoding orientation varies considerably with the location and orientation of the short line stimulus
as modulated by the underlying orientation preference map. The average encoding error depends only weakly on the structure
of the orientation preference map and is much smaller than the human error of estimating orientation measured psychophysically.
From this comparison we conclude that the actual mechanism of orientation perception does not make efficient use of all the
information available in the neuronal responses and that it is the decoding of visual information from neuronal responses
that limits psychophysical performance.
Action Editor: Terrence Sejnowski |
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Keywords: | Population coding Cortical feature maps Fisher information Oblique effect Early version |
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