“…Some neurons in the prefrontal cortex fire preferentially at the beginning of action sequences [36], while others remain active for the duration of the sequence [37]. These signals go to both the SMA/PM region, and to the basal ganglia and cerebellum, where they are hypothesized to select [23,36,31] and pace [29,31] action sequences, respectively. Neurons with sequence-specific activity, i.e., sequence identifiers, have been shown in pre-SMA, while neurons encoding element order in action sequences have been found in both PFC and SMA [3,38,9,7,10,36].…”