Title: "Neural mechanisms of
attention in monkey extrastriate visual cortex"
John H. Reynolds
Systems Neurobiology Laboratory, The
Salk
Abstract:
Visual perception seems effortless, but
psychophysical experiments show that the brain is severely limited in the
amount of visual information it can process at any moment in time. For instance, when people are asked to
identify the objects in a briefly presented scene, they become less accurate as
the number of objects increases. The inability to process more than a few
objects at a time reflects the limited capacity of some stage (or stages) of
sensory processing, decision-making, or behavioral control. Somewhere between
stimulating the retina and generating a behavioral response, objects compete
with one another to pass through this computational bottleneck.
What are the neural mechanisms underlying this
competition? How are they influenced by
intrinsic properties of the stimulus, such as its visual salience? How does
visual attention modulate this competition to select out behaviorally relevant
stimuli while suppressing irrelevant distractors? I will describe a series of single-unit
recording experiments we have conducted to address these questions. The results
of these experiments clarify the role of attention in modulating visual
signals, and provide a set of constraints that rule out some possible models of
extrastriate visual processing. I will present a simple cortical circuit that
satisfies these constraints.