Rapid reformatting of the cortical code during active tactile discrimination

Abstract

Touch-based object recognition relies on perception of compositional tactile features like roughness, shape, and surface orientation. However, besides roughness, it remains unclear how these different tactile features are encoded to guide perception. Here, we establish a barrel cortex-dependent perceptual task in which mice discriminate tactile gratings based on orientation using only their whiskers. Multi-electrode recordings in barrel cortex reveal weak orientation tuning in average firing rates during grating exploration despite high levels of cortical activity. Just before decision, orientation information extracted from fast cortical dynamics more closely resembles concurrent psychophysical measurements than single neuron orientation tuning curves. This temporal code conveys both stimulus and choice-related information, suggesting that fast cortical dynamics during exploration of a tactile object both reflect the physical stimulus and impact the upcoming perceptual decision of the animal.