Neuronal Activity in the Dorsal Premotor Area and Ventral Premotor Area of Monkeys adapting to a New Dynamic Environment

In a series of experiments, we investigated how neurons in the different motor areas of the frontal lobe reflect the movement dynamics, and how their neuronal activity undergoes plastic changes when monkeys learn a new dynamics. Here we describe the results obtained in the dorsal premotor area (PMd) and ventral premotor area (PMv). Monkeys performed visually instructed, delayed reaching movements before, during and after exposure and adaptation to a perturbing force field. The experimental design allowed dissociating the neuronal activity related to the movement dynamics from that related to the movement kinematics, and to investigate the neuronal plasticity associated with motor learning. During movement planning (i.e., during an instructed delay that followed the cue and preceded the go signal), dynamics-related activity was found in PMd but not in PMv. In contrast, neurons in both PMd and PMv reflected the movement dynamics during movement execution. In both PMd and PMv, neurons displayed plastic changes associated with the acquisition of a new dynamics, similar to that previously observed in the primary motor cortex (M1).