Oxyopia Abstract

October 6, 2006
Friday, 4 PM
489 Minor Hall

Curtis Baker, PhD
Professor, McGill Vision Research Unit, Dept. of Ophthalmology, McGill University, Montreal
Host: Jack Gallant

Title

Representation of contrast- and texture-defined boundaries in early visual cortex

Abstract

In the natural world we routinely perceive objects which are distinguished from their backgrounds by global differences in local luminance, contrast, texture, etc. Visual cortex mechanisms selective to luminance-defined oriented contours are well known, but only recently have we begun to understand a parallel set of mechanisms sensitive to differences of contrast or texture.

Neurophysiological studies in early visual cortex reveal that many single neurons are selective to both local textural and global contour attributes of visual stimuli, while optical imaging demonstrates coarse-scale anatomical compartments for contour properties which are largely invariant to texture attributes. Computational analyses of natural image statistics, based on models derived from neurophysiology, indicate scale-invariance of textural information in natural images, and its co-occurrence with luminance-defined information.

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