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The Journal of Neuroscience, 1999, 19:RC44:1-5

RAPID COMMUNICATION
Organization of Intracortical Circuits in Relation to Direction Preference Maps in Ferret Visual Cortex

B. Roerig¹ and J. P. Y. Kao²

¹ Department of Anatomy and Neurobiology and ² Medical Biotechnology Center and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201

Neurons in the primary visual cortex are selective for the direction of movement of a visual stimulus. Like other stimulus features, direction preference is mapped on the cortical surface in a systematic manner. Intracortical synaptic circuits, in particular inhibitory connections, have been implicated in the emergence of direction selectivity. Whether intracortical inhibition specifically suppresses responses to the nonpreferred direction or has a nonspecific "thresholding" effect is still controversial. To address these questions we investigated the relationship between patterns of intracortical synaptic connections and direction domains in ferret primary visual cortex (area 17) using a combined in vivo-in vitro approach. Excitatory synaptic inputs were iso-direction-tuned. The majority of local inhibitory inputs were also iso-direction-tuned. However, ~40% of inhibitory connections originated in regions preferring the opposite direction. These findings indicate that specific inhibitory interactions between cortical regions of opposite direction preference may contribute to the emergence and sharpening of direction selectivity.

Key words: visual cortex; direction selectivity; optical imaging; photostimulation; intracortical circuits; inhibition

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Copyright © 0000 Society for Neuroscience  0270-6474/0/$05.00/0

This article has been cited by other articles:

				M. Gur and D. M. Snodderly Direction selectivity in V1 of alert monkeys: evidence for parallel pathways for motion processing J. Physiol., December 1, 2007; 585(2): 383 - 400. [Abstract] [Full Text] [PDF]

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