Neural State Changes in Primate Motor Cortex During Arm Movements with Distinct Control Requirements

The primary motor cortex (M1) is an important structure of the motor system that contributes to many aspects of movement. Firing patterns of M1 neurons can be surprisingly complex, and there is substantial interest in understanding these patterns and their relation to behavior. Here, we characterize the temporal structure of M1 activity during reaching in several ways. First, we show that single neurons encode movement information in a series of discrete segments. Information is stably encoded during each brief segment, and the firing patterns of most neurons transition between segments at similar times during movement. This pattern may therefore reflect transitions between different neural “states.” Next, we establish that the sequence of states observed during behavior is related to a sequence of distinct drivers, including visuospatial information and visual feedback from a movement. If no feedback is provided, neurons may produce a truncated response sequence. Last, we link the temporal structure of firing patterns to the structure of reaches and demonstrate that the classical two-component model of reaching is reflected in M1 activity. Our findings may help establish a useful framework for interpreting seemingly complex neural activity during behavior