Neural correlates of mental rehearsal in dorsal premotor cortex

Behavioural and imaging studies suggest that when humans mentally rehearse a familiar action they execute some of the same neural operations used during overt motor performance(1-9). Similarly, neural activation is present during action observation in many of the same brain regions normally used for performance, including premotor cortex(6-9). Here we present behavioural evidence that monkeys also engage in mental rehearsal during the observation of sensory events associated with a well-learned motor task. Furthermore, most task-related neurons in dorsal premotor cortex exhibit the same activity patterns during observation as during performance, even during an instructed-delay period before any actual observed motion. This activity might be a single-neuron correlate of covert mental rehearsal.