Fast cortical dynamics encode tactile grating orientation during active touch

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 by neural activity that is linked with perception. Here, we
establish a 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/action-related
information, suggesting that fast cortical dynamics during exploration of
a tactile object both reflect the physical stimulus and impact the
decision.