Reorganization of Neural Activity in Cerebral Cortex during Adaptation to External Force Perturbations of Reaching Movement

Knowledge of the properties of motor cortical neurons is crucial for solving the problem of developing a flexible and robust brain-computer interface (BCI). The results of chronic multielectrode recording from the primary motor cortical area of monkey brain during the animal\´s performance of a center-out 3D reaching task and adaptation to external force perturbation of the movement are described. Recruitment of new cells was observed in the dorsal premotor and primary motor cortex. This consisted of the gradual, day-to-day development of a directional tuning pattern (DTP) of spike activity. In many neurons an "exploratory" variation of DTP was observed. The intensity of variation gradually decreased by the end of adaptation, usually converging to a new pattern. The resulting DTP was retained for at least several days after perturbations were discontinued. The results suggest that the brain cortex can be viewed as a pool of functionally flexible processing elements that can be dynamically recruited into a system controlling the performance of a given motor task and individually adjusted as required for motor learning