TOPOGRAPHICAL MAPS OF ORIENTATION SPECIFICITY

A spatially congruent framework for orientation encoding in the primat e striate visual cortex is proposed and discussed. This framework, whi ch is based on the foot-of-normal representation of straight lines, no t only provides a reasonable explanation for the centric organization of the orientation specificity in the primate striate visual cortex bu t also accounts for a series of experimentally verified intriguing phe nomena such as the lack of orientation specificity around the centres of the orientation modules (i.e. the singularities), the increased neu ral activity at these same places, and the relatively uniform distribu tion of the singularities along the ocular dominance columns. The prop osed framework can also explain and predict the possible existence of centric modules in other cortical regions containing topographical map s of two-dimensional sensory spaces (e.g. pre-striate and somatic sens ory cortex). A simple one-layer neural model of the basic centric modu le in the framework is presented, and simulation results are discussed .