Topographical maps of orientation specificity

Abstract

A spatially congruent framework for orientation encoding in the primate striate visual cortex is proposed and discussed. This framework, which is based on the foot-of-normal representation of straight lines, not only provides a reasonable explanation for the centric organization of the orientation specificity in the primate striate visual cortex but also accounts for a series of experimentally verified intriguing phenomena such as the lack of orientation specificity around the centres of the orientation modules (i.e. the singularities), the increased neural activity at these same places, and the relatively uniform distribution of the singularities along the ocular dominance columns. The proposed framework can also explain and predict the possible existence of centric modules in other cortical regions containing topographical maps of two-dimensional sensory spaces (e.g. pre-striate and somatic sensory cortex). A simple one-layer neural model of the basic centric module in the framework is presented, and simulation results are discussed.