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Spatial Overlap of ON and OFF Subregions and Its Relation to Response Modulation Ratio in Macaque Primary Visual Cortex
Mario L. Mata[1] and Dario L. Ringach[2]

1 - Department of Neurobiology, David Geffen School of Medicine; and

2 - Departments of Neurobiology and Psychology, Biomedical Engineering Interdepartmental Program, Brain Research Institute, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, California

J Neurophysiol 93: 919-928, 2005. First published September 15, 2004; doi:10.1152/jn.00668.2004
0022-3077/05 $8.00

Submitted 2 July 2004; accepted in final form 8 September 2004

We studied the spatial overlap of ON and OFF subregions in macaque primary visual cortex and its relation to the response modulation ratio (the F1/F0 ratio). Spatial maps of ON and OFF subregions were obtained by reverse correlation with a dynamic noise pattern of bright and dark spots. Two spatial maps, ON and OFF, were produced by cross-correlating the spike train with the location of bright and dark spots in the stimulus respectively. Several measures were used to assess the degree of overlap between subregions. In a subset of neurons, we also computed the F1/F0 ratio in response to drifting sinusoidal gratings. Significant correlations were found among all the overlap measures and the F1/F0 ratio. Most overlap indices considered, and the F1/F0 measure, had bimodal distributions. In contrast, the distance between on and off subregions normalized by their size was unimodal. Surprisingly, a simple model that additively combines ON and OFF subregions with spatial separations drawn from a unimodal distribution, can readily explain the data. These analyses clarify the relationship between subregion overlap and the F1/F0 ratio in macaque primary visual cortex, and a simple model provides a parsimonious explanation for the co-existence of bimodal distributions of overlap indices and a unimodal distribution of the normalized distance.

Address for reprint requests and other correspondence: D. Ringach, Dept of Psychology, Franz Hall, Rm 7613, University of California, Los Angeles, CA 90095-1563 (E-mail: [email protected] )


"This lab performed animal experiments involving pain or distress but no analgesics, anesthetics or pain relievers were administered."

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Rats, mice, birds, amphibians and other animals have been excluded from coverage by the Animal Welfare Act. Therefore research facility reports do not include these animals. As a result of this situation, a blank report, or one with few animals listed, does not mean that a facility has not performed experiments on non-reportable animals. A blank form does mean that the facility in question has not used covered animals (primates, dogs, cats, rabbits, guinea pigs, hamsters, pigs, sheep, goats, etc.). Rats and mice alone are believed to comprise over 90% of the animals used in experimentation. Therefore the majority of animals used at research facilities are not even counted.

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