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Faculty List
Richard A. Andersen
andersen@vis.caltech.edu
www.vis.caltech.edu
Ph.D. 1979, University of California - San Francisco
Neural Mechanisms for Visual-Motor Integration, Spatial Perception and Motion Perception
Work in my laboratory has focused on the role of the posterior parietal cortex in visual-motor integration, spatial perception, and visual-motion analysis. The posterior parietal cortex is the end point of one of the two major streams of visual processing in the primate visual cortex. The pathway to the parietal cortex is located in dorsal areas of the extrastriate cortex and is involved in spatial aspects of visual processing. It is functionally distinct from the more ventral pathway, which is concerned with color and form perception.
We are studying the role of this area in the kinematics of visual-motor integration. At issue is the fact that visual information is gathered in retinal coordinates and is represented in many structures retinotopically. However, at some point in the nervous system, this information must be converted to spatial coordinate frames for programming accurate motor activity in the world. We have found that the posterior parietal cortex transforms visual information from retinal to head-and body-centered coordinates, and we are presently studying the mechanisms by which this is accomplished.
Recently we discovered an area in the posterior parietal cortex (the lateral intraparietal area, LIP) which is involved in the planning of eye movements. We are currently studying the role of LIP in the planning of sequences of eye movements, how LIP activity changes with changes in motor plans, and how area LIP can use both visual and auditory information in encoding eye movements.
Several cortical areas within the posterior parietal cortex are involved in processing higher order aspects of motion perception. We have developed novel motion stimuli using high-speed computer graphic techniques to study the role of these areas in motion analysis. We use these stimuli to test the monkey motion processing system psychophysically and directly compare it to that of humans. These experiments have focused on the ability to perceive the structure of objects or the environment based purely on motion cues. We have also begun to use these powerful motion stimuli in conjunction with lesion and single cell recording techniques to examine the processing role of each cortical level in the motion processing pathway that includes primary visual cortex, extrastriate cortex and areas in the posterior parietal cortex.
Self portraits of stroke patient (German artist Anton Roderscheidt) with damage to right parietal cortex. Portraits were drawn 2 mo (upper left), 3.5 mo (upper right), 6 mo (lower left), and 9 mo (lower right) postlesion. Earlier portraits show face contralateral to lesion severely "neglected".
