title: Correlations in V1 are reduced by stimulation outside the receptive field.
abstract: The trial-to-trial response variability of nearby cortical neurons is correlated. These correlations may strongly influence population coding performance. Numerous studies have shown that correlations can be dynamically modified by attention, adaptation, learning, and potent stimulus drive. However, the mechanisms that influence correlation strength remain poorly understood. Here we test whether correlations are influenced by presenting stimuli outside the classical receptive field (RF) of visual neurons, where they recruit a normalization signal termed surround suppression. We recorded simultaneously the activity of dozens of cells using microelectrode arrays implanted in the superficial layers of V1 in anesthetized, paralyzed macaque monkeys. We presented annular stimuli that encircled--but did not impinge upon--the RFs of the recorded cells. We found that these "extra-classical" stimuli reduced correlations in the absence of stimulation of the RF, closely resembling the decorrelating effects of stimulating the RFs directly. Our results suggest that normalization signals may be an important mechanism for modulating correlations.
authors.affiliation: Department of Ophthalmology, Center for the Neural Basis of Cognition, and.
authors.forename: Adam C
authors.identifier: http://orcid.org/0000-0003-1794-035X
authors.initials: AC
authors.lastname: Snyder
authors.affiliation: Department of Ophthalmology, Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, and.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Morais
authors.affiliation: Dominick Purpura Department of Neuroscience and Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, New York, New York 10461.
authors.forename: Adam
authors.initials: A
authors.lastname: Kohn
authors.affiliation: Department of Ophthalmology, Center for the Neural Basis of Cognition, and Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, and smithma@pitt.edu.
authors.forename: Matthew A
authors.identifier: http://orcid.org/0000-0003-1192-9942
authors.initials: MA
authors.lastname: Smith
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000465:Algorithms; D000818:Animals; D008252:Macaca fascicularis; D008297:Male; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation; D013223:Statistics as Topic; D014793:Visual Cortex / Q000166:cytology*; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
keywords: V1; electrophysiology; extra-classical receptive field; population coding; spike count correlation; surround suppression