FUNCTIONAL MAGNETIC-RESONANCE-IMAGING OF COMPLEX HUMAN MOVEMENTS

Functional magnetic resonance imaging (FMRI) is a new, noninvasive ima ging tool thought to measure changes related to regional cerebral bloo d flow (rCBF). Previous FMRI studies have demonstrated functional chan ges within the primary cerebral cortex in response to simple activatio n tasks, but it is unknown whether FMRI can also detect changes within the nonprimary cortex in response to complex mental activities. We th erefore scanned six right-handed healthy subjects while they performed self-paced simple and complex finger movements with the right and lef t hands. Some subjects also performed the tasks at a fixed rate (2 Hz) or imagined performing the complex task. Functional changes occurred (1) in the contralateral primary motor cortex during simple, self-pace d movements; (2) in the contralateral (and occasionally ipsilateral) p rimary motor cortex, the supplementary motor area (SMA), the premotor cortex of both hemispheres, and the contralateral somatosensory cortex during complex, self-paced movements; (3) with less intensity during paced movements, presumably due to the slower movement rates associate d with the paced (relative to self-paced) condition; and (4) in the SM A and, to a lesser degree, the premotor cortex during imagined complex movements. These preliminary results are consistent with hierarchical models of voluntary motor control.