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Neuron, Vol. 18, 865872, June, 1997, Copyright 1997 by Cell Press Neural Mechanisms of Visual Review

Summary: Neuron, Vol. 18, 865872, June, 1997, Copyright 1997 by Cell Press
Neural Mechanisms of Visual Review
Motion Perception in Primates
Richard A. Andersen functional localization, shape perception, pattern per-
Division of Biology ception, spatial awareness, figure-ground segregation,
California Institute of Technology attention, and decision making.
Pasadena, California 91125
Introduction Hierarchical Processing
The motion pathway begins in area V1 where cells are
A large extent of the posterior cortex of the primate found that are direction selective (Figure 1). Direction
brain is devoted to vision, and it contains two general selectivity refers to the fact that these cells respond
streams that process visual information. The one stream best when a stimulus moves in a particular direction
is situated more ventrally in the cortex and is important within the cell's receptive field. The response decreases
for object recognition,pattern recognition, colorpercep- progressively as the direction of motion differs more
tion, and shape perception. These attributes of visual and more from the preferred direction. The direction
analysis weassociate with visual awareness or "seeing", selective neurons are concentrated within layer 4B of
and thus this stream has been referred to as the "what" V1 and project preferentially to cortical fields involved
system because it recognizes objects (Ungerleider and in motion processing including area MT (Maunsell and
Mishkin, 1982). A second, more dorsal stream is associ- Van Essen, 1983). Moving along the motion hierarchy,
ated with visual-motor transformations--that is, the the receptive fields become increasingly larger; in area


Source: Andersen, Richard - Division of Biology, California Institute of Technology


Collections: Biology and Medicine