Population coding in cortical area MST.

Full Abstract

Disparity steps applied to large patterns elicit vergence eye movements at ultrashort latencies. Disparity tuning curves, describing the dependence of the amplitude of the initial vergence responses on the amplitude of the disparity steps, resemble the derivative of a gaussian and indicate that appropriate servo-like behavior occurs only with small disparity steps (<1 degree). Lesion data from monkeys suggest that these vergence responses are mediated, at least in part, by neurons in the medial superior temporal area of the cerebral cortex, and we here review a recent study of the associated single unit activity in that area. Few medial superior temporal neurons have disparity tuning curves whose shapes resemble the tuning curve for vergence. Yet, when the disparity tuning curves for all of the disparity-sensitive cells recorded from a given monkey are summed together, they match the tuning curves for the vergence responses of that monkey very closely, even reproducing that animal's idiosyncracies. When all of the spike trains elicited by a given disparity step are summed together to give an average discharge profile for the whole population of recorded cells, many are noisy, but others that are less so match the temporal profile of the motor response, vergence velocity, quite well. We conclude that the discharges of the disparity-sensitive cells in the medial superior temporal area each represent only a very limited aspect of the sensory stimulus (and/or associated motor response?), but when pooled together, they provide a complete description of the vergence velocity motor response:
population coding.

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Author information

Author/s: Takemura, A (A); Kawano, K (K); Quaia, C (C); Miles, F A (FA);

Affiliation: Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukubashi, Ibaraki 305-8568, Japan.

Journal and publication information

Publication Type: Journal Article; Review

Journal: Annals of the New York Academy of Sciences (Ann N Y Acad Sci), published in United States. (Language: eng)

Reference: 2002-Apr; vol 956 (issue ) : pp 284-96

Dates: Created 2002/04/18; Completed 2002/06/06; Revised 2005/11/16;

PMID: 11960812, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals
Cerebral Cortex - physiology
Convergence, Ocular - physiology
Eye Movements - physiology
Humans
Neurons - physiology

Neurons - physiology
Pursuit, Smooth
Reaction Time
Temporal Lobe - physiology
Vision Disparity - physiology
Visual Cortex - physiology

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