Linear and nonlinear mechanisms of motion selectivity in single neurons of the cat´s visual cortex

Motion selectivity, and especially directional selectivity (DS), in complex cells of the cat´s striate visual cortex depends primarily on nonlinear interactions between responses to spatially and temporally separated 2-bar components of a moving stimulus. DS simple cells were tested with optimally oriented bar-pairs. it is shown that DS always depends on nonlinear 2-bar interactions and in the example shown, does not depend significantly on 1-bar responses. These 2-bar interactions are inseparable in space-time in a way that is similar to that the authors have found previously in complex cells, which suggests that a primary function of the cat´s striate cortex is to generate nonlinear spatiotemporal interactions necessary for motion processing