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Banbury Center Workshop Series

Neurocomputational Strategies: From Synapses to Behavior (1998)
Functional Organization of the Thalamus and Cortex and their Interactions (1999)
Toward Animal Models of Attention and Consciousness (2000)
Persistent Neural Activity (2000)
Can a Machine Be Conscious? (2001)
Communication in Brain Systems (2004)
Neurobiology of Decision-Making (2005)
Computational Approaches to Cortical Functions (2006)
New Frontiers in Studies of Nonconscious Processing (2007)
Theoretical and Experimental Approaches to Auditory and Visual Attention (2008)
Searching for Principles Underlying Memory in Biological Systems (2009)
Neuronal Response Variability and Cortical Computation (2011)
Connections and Communication in the Brain (2014)

John Reynolds

Visual Salience, Competition, Neuronal Response Synchrony and Selective Attention

Salk Institute

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 many possible models of extrastriate visual processing. I present a simple cortical circuit that satisfies these constraints and suggests a computational role for recently observed changes in neuronal synchronization with attention.