The cerebellum and parietal cortex play a specific role in coordination: Apet study

The synthesis of complex, coordinated movements from simple actions is an i mportant aspect of motor control. Lesion studies have revealed specific bra in areas, particularly the cerebellum, to be essential for a variety of coo rdinated movements, and lend support to the view that the cerebellum is eng aged in the integration of simple movements into compound ones. A PET study was therefore conducted to show which brain areas were active specifically during the coordinated execution of an arm and finger movement to visual t argets. A two-by-two factorial design was employed, in which subjects eithe r made arm or finger movements alone, made coordinated arm-finger movements , or made no movements. Voxels were identified where activity was significa ntly greater during the execution of coordinated movements than when moveme nts were made alone and in which this increased activity could not be accou nted for simply by the additive effects of the activations for each movemen t in isolation. The behavioral results showed that subjects coordinated arm and finger movements well during coordination scans. Coordination-specific activations were found in left anterior lobe and bilaterally in the parame dian lobules of the cerebellum. These are known to receive forelimb-specifi c spinocerebellar proprioceptive inputs that may be related to multijoint m ovements. The same areas also receive corticocerebellar afference from moto r areas that may convey efference copy information to the cerebellum. Coord ination-specific activations were also seen in areas of the posterior parie tal cortex. The results provide direct evidence in healthy human subjects o f specific cerebellar engagement during the coordination of movement, over and above the control of constituent movements. (C) 2001 Academic Press.