Propagating Waves as a Cortical Mechanism of Direction-Selectivity in V1 Motion Cells

The majority of neurons in primary visual cortex respond preferentially to moving bars of light with a specific orientation and direction of motion. The directional selectivity of those neurons implies that their responses cannot be achieved with separate spatial and temporal neural processes. How cortical neurons achieve non-separable space-time responses is still a mystery. We present a mathematical model of visual cortex in which neurons are predisposed to traveling waves of activity in a given anatomical direction. Those neurons resonate vigorously with moving stimuli that have a similar space-time signature to the intrinsic traveling wave. Yet they are quiescent to stimulus motion in the opposite direction. The model demonstrates how direction-selectivity can arise from the spatiotemporal properties of intrinsic cortical activity without resort to explicit time delays.