Kukjin Kang, 9/23/03
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Information Tuning of a Population of Neurons in Primary Visual Cortex
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Neurons in macaque primary visual cortex (V1) show a diversity of
orientation tuning properties, exhibiting a broad distribution of tuning
width, baseline activity, peak response, and circular variance (CV).  In
this work we study how the different tuning features affect the
performance of these cells in discriminating between stimuli with
different orientations. Previous studies of the orientation discrimination
power of neurons in V1 focused on resolving two nearby orientations close
to the psychophysical threshold of orientation discrimination. Here we
develop a theoretical framework, the information tuning curve, which
measures the discrimination power of cells as a function of the
orientation difference, , of the two stimuli. This tuning curve also
represents the mutual information between the neuronal responses and the
stimulus orientation. We study theoretically the dependence of the
information tuning curve on the orientation tuning width, baseline and
peak responses.  Of main interest is the finding that narrow orientation
tuning is not necessarily optimal for all angular discrimination tasks.
Instead, the optimal tuning width depends linearly on . We have applied
our theory to study the discrimination performance of a population of 490
neurons in macaque V1. We find that a significant fraction of the neuronal
population exhibits favorable tuning properties for large s. We also study
how the discrimination capability of neurons is distributed and compare
several other measures of the orientation tuning such as circular variance
with Chernoff distances for normalized tuning curves.