Activation of the ventral and mesial frontal cortex of the monkey by self-initiated movement tasks as revealed by positron emission tomography.

In order to investigate the neural mechanisms of movement initiation, we measured the regional cerebral blood flow (rCBF) of the monkey during self-initiated and visually-initiated hand movement tasks using positron emission tomography (PET). The orbitofrontal, cingulate, and anteromedial part of the dorsal premotor areas were preferentially activated by the self-initiated hand movement task (SELF). The pre-supplementary motor area and the cingulate motor area were also included in the active foci during the task. In the visually-initiated task (VISUAL), the V1, V2, V3, V3A, and V4 were activated, whereas the activity of the dorsolateral premotor and primary motor areas was not significantly different between the two tasks. These findings suggest that the orbitofrontal and mesial frontal cortices play an important role in the neural processes involved in self-initiation of movement and self-regulation of inner drives.