A Neuromorphic Multi-chip Model of a Disparity Selective Complex Cell

The relative depth of objects causes small shifts in the left and right retinal positions of these objects, called binocular disparity. Here, we describe a neuromorphic implementation of a disparity selective complex cell using the binocular energy model, which has been proposed to model the response of disparity selective cells in the visual cortex. Our system consists of two silicon chips containing spiking neurons with monocular Gabor-type spatial receptive fields (RF) and circuits that combine the spike outputs to compute a disparity selective complex cell response. The disparity selectivity of the cell can be adjusted by both position and phase shifts between the monocular RF profiles, which are both used in biology. Our neuromorphic system performs better with phase encoding, because the relative responses of neurons tuned to different disparities by phase shifts are better matched than the responses of neurons tuned by position shifts.