Fast cortical dynamics encode tactile grating orientation during active touch

Abstract

Touch-based object recognition relies on perception of compositional tactile features like roughness, shape, and orientation. However, it remains unclear how the underlying spatio-temporal information from tactile sensors is integrated to form such percepts. Here, we establish a barrel cortex-dependent perceptual task in which mice use their whiskers to discriminate tactile gratings based on orientation. Multi-electrode recordings in barrel cortex during task performance reveal weak orientation tuning in the firing rate of single neurons during grating exploration despite high cortical firing rates. However, population-based classifiers decode grating orientation in line with concurrent psychophysical measurements and correlate with decisions on a trial-by-trial basis. For better decoding performance, the precise temporal sequence of population activity is necessary during grating exploration but becomes dispensable after decision. Our results suggest that temporal sequences of activity in barrel cortex carry orientation information during exploration. This code is reformatted around decision time to make firing rates more informative.