From intention to action: motor cortex and the control of reaching movements.

The motor cortex was experimentally identified more than a century ago using surface electrical stimulation and lesions. Those first studies initiated a debate about the role of the motor cortex in the control of voluntary movement that continues to this day. The main issue concerns the degree to which the descending motor command emanating from the motor cortex specifies the spatiotemporal form of a movement or its causal forces, torques and muscle activity. The neurophysiological evidence supports both perspectives. This chapter surveys some of that evidence, with particular focus on the latter, more 'traditional', role of motor cortex.