Visuomotor mismatch responses as a hallmark of explaining away in causal inference

Abstract

How are visuomotor mismatch responses in visual cortex embedded into cortical processing? We here argue that mismatch responses are best understood as the result of a cooperation of motor and visual areas to jointly explain optic flow. This cooperation ensures that optic flow is not explained redundantly by both areas, which in the language of causal inference is termed explaining away. This improves the efficiency of the resulting neural code, and allows the animal to easily detect movements that are independent of its own locomotion. We demonstrate the emergence of mismatch responses from explaining away in simulations, where spiking neurons learn to encode optic flow stimuli and locomotion. We furthermore lay out arguments against the prevailing idea that mismatch signals are the result of a dedicated error computation in a hierarchical model. These results provide a new perspective on several recent experiments of cross-modal neural interactions in cortex.