The cortical motor system

The cortical motor system of primates is formed by a mosaic of anatomically and functionally distinct areas. These areas are not only involved in moto r functions, but also play a role in functions formerly attributed to highe r order associative cortical areas. In the present review, we discuss three types of higher functions carried out by the motor cortical areas: sensory -motor transformations, action understanding, and decision processing regar ding action execution. We submit that generating internal representations o f actions is central to cortical motor function. External contingencies and motivational factors determine then whether these action representations a re transformed into actual actions.