Research Faculty & Scientific Programs

Brad C Motter, Ph.D. Associate Professor, Neuroscience and Physiology RESSV151 Weiskotten Hall Upstate Medical University 750 East Adams Street Syracuse, NY 13210 (315) 425-4873

Education and Clinical Training

Research Program and Department Affiliations

Research Interests

Research Abstract

Cortical Mechanisms of Cognitive Processes: Attention.

This project addresses issues concerned with the basic functional processes underlying vision. Neurophysiological processes involved in the selection of candidate targets during visual search, detection, and discrimination are examined in extrastriate visual cortical areas. Recently we reported neurophysiological evidence that simple objects in the visual field can be dynamically segregated on the basis of color or luminance. The neural activity reflects an attentive selection process and not simply the physical attributes of the stimuli. The resulting topographic representation of the neural activity highlights the targets of visual search in the scene at the expense of background objects. Our broad objectives are to provide a better functional basis for the clinical understanding of attentive and cognitive disorders.

Psychophysical Studies of Active Visual Search We are examining the spatial extent of focal attentive processing during active visual search by modeling the probability of target discovery. We have found that target detection is constrained by the density of object representation in primary visual cortex. We have further shown that the object density is dynamically controlled by a selective process that operates on the basis of object features. Attentive selection for color, for example, constrains effective density to just objects having the selected color. Search performance can be fully accounted for by a combination of the density constraint and a simple item to item random walk through the set of relevant items. Characterization of this basic search constraint now allows us to proceed to investigate the search performance under conditions of various background noise and interference from nearby and partially occluding items. We continue to develop the mathematical analysis of visual search performance using a combination of human and animal psychophysical studies.

Selected References

Motter, B.C. and Belky, E.J. The zone of focal attention during active visual search. Vision Research, 38 (1998) 1007-1022.

Motter, B.C. and Holsapple, J.W. Cortical image density determines the probability of target discovery during active search. Vision Research, 40(2000)1311-1322.

Motter, B.C. Neural correlates of color and luminance feature selection in extrastriate area V4. J. Neurosci., 14 (1994) 2178-2189.

This profile was last updated on 09/29/2008

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