Neuronal control and monitoring of initiation of movements.

The prerequisite for behavioral self-control is the ability to initiate actions and to cancel planned actions. A rational choice about which action to initiate or to withhold must be informed by the consequences of prior actions. The neuronal correlates of these processes have been studied with the countermanding paradigm. This task requires subjects to withhold planned movements in response to an imperative stop signal, which they can do with varying success. By recording the activity of single neurons in different parts of the frontal cortex of macaque monkeys performing this task, signals that are sufficient for controlling the initiation and inhibition of movements and other signals that evaluate the consequences of these movements have been identified. Copyright 2002 Wiley Periodicals, Inc.