Suarez, Humbert and Koch, Christof and Douglas, Rodney (1995) Modeling direction selectivity of simple cells in striate visual cortex within the framework of the canonical microcircuit. Journal of Neuroscience, 15 (10). pp. 6700-6719. ISSN 0270-6474. http://resolver.caltech.edu/CaltechAUTHORS:20130816-103230986
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Nearly all models of direction selectivity (DS) in visual cortex are based on feedforward connection schemes, where geniculate input provides all excitatory synaptic input to both pyramidal and inhibitory neurons. Feedforward inhibition then suppresses feedforward excitation for nonoptimal stimuli. Anatomically, however, the majority of asymmetric, excitatory, synaptic contacts onto cortical cells is provided by other cortical neurons, as embodied in the Canonical Microcircuit of Douglas and Martin (1991). In this view, weak geniculate input is strongly amplified in the preferred direction by the action of intracortical excitatory connections, while in the null direction inhibition reduces geniculate-induced excitation. We investigate analytically and through biologically realistic computer simulations the functioning of a cortical network based on massive excitatory, cortico-cortical feedback. The behavior of this network is compared to physiological data as well as to the behavior of a purely feedforward model of DS based on nonlagged input. Our model explains a number of puzzling features of direction selective simple cells, including the small somatic input conductance changes that have been measured experimentally during stimulation in the null direction, and the persistence of DS while fully blocking inhibition in a single cell. Although the operation at the heart of our network is amplification, the network passes the linearity test of (Jagadeesh et al., 1993). We make specific predictions concerning the effect of selective blockade of cortical inhibition on the velocity-response curve.
|Additional Information:||© 1995 by Society for Neuroscience. Received Mar. 14, 1995; revised may 30, 1995; accepted June 16, 1995. This research was supported by the Office of Naval Research, the Air Force Office of Scientific Research, the National Science Foundation, the Medical Research Council, and the Gatsby Foundation. H.S.S. was supported by NIH grant EY06264-03, a Parsons Foundation Fellowship, and an NSF Graduate Fellowship. We thank Kevan Martin, Ojvind Bernander, and Gary Holt for many fruitful discussions and their help.|
|Group:||Koch Laboratory, KLAB|
|Subject Keywords:||direction selectivity, simple cells, visual cortex, cortico-cortica/ connections, excitatory feedback, canonical microcircuit, computer modeling|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||KLAB Import|
|Deposited On:||26 Jan 2008 05:08|
|Last Modified:||03 Apr 2014 20:53|
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