MOTOR CORTICAL RESPONSES TO VIBRISSAL INPUT ARE CONTEXT SPECIFIC

The primary motor cortex (M1) is well positioned to transform sensory and contextual information into behavior. Although recent work has shown that M1 exhibits fast and robust sensory responses, it remains unclear whether neurons are broadly recruited across behavioral conditions or selectively engaged in context-dependent actions.
To address this, we trained mice on multiple sensorimotor tasks, including a cue-triggered whisking-to-touch task, an air-puff–triggered licking task, and trials with unexpected air-puff stimuli. Fast-spiking and regular-spiking neurons in layers 2/3 and 5 responded robustly within ~15 ms to expected air-puff stimuli, with stronger responses from fast spiking putative interneurons. In contrast, these same neurons were only weakly modulated during goal-directed whisking-to-touch behavior. Unexpected air puffs recruited fewer neurons than expected stimuli, resulting in overall weaker responses. Trials with reduced neural responses to air puffs were associated with increased post–air-puff whisking.
We observed a broad range of response profiles, including both transient and persistent activity, which did not map onto classical cellular features such as spike waveform duration or cortical depth. Together, these results indicate that most M1 neurons recruited during whisker-stimulus–triggered licking do not multiplex across tasks. Instead, M1 activity is strongly context dependent and more closely related to action selection than to generalized sensory encoding.