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Cereb Cortex. 2015 Sep;25(9):3182-96. doi: 10.1093/cercor/bhu111. Epub 2014 Jun 5.

Local and Global Correlations between Neurons in the Middle Temporal Area of Primate Visual Cortex.

Author information

1
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.
2
School of Medicine, University of Western Sydney, Campbelltown, NSW 2560, Australia.
3
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.

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.

KEYWORDS:

area MT; extrastriate; marmoset; population coding; visual motion

PMID:
24904074
DOI:
10.1093/cercor/bhu111
[Indexed for MEDLINE]

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