Modifications of motor cortical activity induced by adaptation to movement perturbations as revealed by chronic multielectrode recordings in monkeys

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 animals performance of a center-out 3D reaching task and adaptation to external force perturbation of the movement are described. Three different types of learning-related modifications of cell spike activity have been identified and described. The most important feature of the first one is the development of anticipatory spike activity preceding the onset of the perturbation. The second and third types are related to the gradual increase of spike activity modulation with respect to the reaching movement and the directional differentiation of this activity reflected in its progressive dependence on the coordinates of the reach target. Adaptive changes of the last type were observed in the rostral-medial part of the primary motor cortex. The capacity of those neurons for this type of adaptation is crucially important for the possibility of their utilization for decoding the direction of subject´s intended movement. It also indicates that the subject´s capability to use a BCI can be improved with training.