Neurophysiological Implementation of a Scheme for Visual Selective Attention
Final rept. 1 Nov 1989-31 Oct 1990
MEDICAL RESEARCH COUNCIL LONDON (UNITED KINGDOM)
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The method of single cell recording in the behaving monkey was used to study mechanisms of selective attention in extrastriate cortex. The animal indicated whether any item in a display of one or more colour patches matched a previously presented target. Recordings were obtained from 186 single cells in cortical area V4. In the match task, attentional selection of the target patch must be controlled by an advance description of the target colour. No evidence for such enduring target descriptions was found in V4 Few if any units showed sustained, target-specific activity. While there was clear evidence for attentional modulation of the visual response, this modulation was quite different from that previously reported for a location selection task. Units did not always respond more strongly when attention was directed to a patch of their preferred colour instead the distribution of attentional preferences was bimodal, with roughly half the cells giving stronger responses when their preferred colour was ignored. Such effects, furthermore, were dependent only on preferences for colour the relevant dimension location preferences seemed immaterial. The findings are inconsistent with hypotheses for attentional selection based on either input gating or selective priming. Alternative possibilities are discussed.
- Anatomy and Physiology