title: Local and Global Correlations between Neurons in the Middle Temporal Area of Primate Visual Cortex.
abstract: In humans and other primates, the analysis of visual motion includes populations of neurons in the middle-temporal (MT) area of visual cortex. Motion analysis will be constrained by the structure of neural correlations in these populations. Here, we use multi-electrode arrays to measure correlations in anesthetized marmoset, a New World monkey where area MT lies exposed on the cortical surface. We measured correlations in the spike count between pairs of neurons and within populations of neurons, for moving dot fields and moving gratings. Correlations were weaker in area MT than in area V1. The magnitude of correlations in area MT diminished with distance between receptive fields, and difference in preferred direction. Correlations during presentation of moving gratings were stronger than those during presentation of moving dot fields, extended further across cortex, and were less dependent on the functional properties of neurons. Analysis of the timescales of correlation suggests presence of 2 mechanisms. A local mechanism, associated with near-synchronous spiking activity, is strongest in nearby neurons with similar direction preference and is independent of visual stimulus. A global mechanism, operating over larger spatial scales and longer timescales, is independent of direction preference and is modulated by the type of visual stimulus presented.
authors.affiliation: ARC Centre of Excellence in Vision Science, Sydney, NSW, Australia Discipline of Physiology, School of Medical Sciences and Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Selina S
authors.initials: SS
authors.lastname: Solomon
authors.affiliation: ARC Centre of Excellence in Vision Science, Sydney, NSW, Australia Discipline of Physiology, School of Medical Sciences and Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Spencer C
authors.initials: SC
authors.lastname: Chen
authors.affiliation: School of Medicine, University of Western Sydney, Campbelltown, NSW 2560, Australia.
authors.forename: John W
authors.initials: JW
authors.lastname: Morley
authors.affiliation: ARC Centre of Excellence in Vision Science, Sydney, NSW, Australia Discipline of Physiology, School of Medical Sciences and Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia Department of Experimental Psychology, University College London, WC1P 0AH, UK.
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Solomon
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D002144:Callithrix; D005260:Female; D008297:Male; D009039:Motion Perception / Q000502:physiology; D009415:Nerve Net / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009949:Orientation; D010775:Photic Stimulation; D013223:Statistics as Topic; D013997:Time Factors; D014793:Visual Cortex / Q000166:cytology*; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology; D014796:Visual Perception
keywords: area MT; extrastriate; marmoset; population coding; visual motion