HEMISPHERIC CONTROL OF MOTOR FUNCTION - A WHOLE-BRAIN ECHO-PLANAR FMRI STUDY

The aim of this study was to explore whether recruitment of the ipsila teral motor cortex during non-dominant motor movement reflects left he mispheric control of motor function or simply the greater complexity o r unfamiliarity of the motor task. BOLD fMRI was performed in normal r ight-handers during two motor tasks: (1) sequential finger movements ( SM task) with the right or left hand; and (2) random finger movements (RM task) with the right hand. In all subjects, activation was predomi nantly in the contralateral motor areas (primary sensorimotor, lateral premotor, parietal and supplementary motor regions) and ipsilateral c erebellum. While the ipsilateral motor areas were also activated, sing le subject analysis revealed these areas to be more extensive and to b e seen in more subjects during the non-dominant hand SM task and domin ant hand RM task than during the more familiar dominant hand SM task. Similarly, group analysis also revealed ipsilateral activation in the primary sensorimotor and lateral premotor areas, but only during the n on-dominant SM task and the dominant hand RM task. Non-dominant hand m ovements, perhaps because they are less 'automatic', appear to require more cortical activity similar to complex tasks with the dominant han d, and result in greater recruitment of ipsilateral cortical motor are as and striatum. The study also illustrates how potentially meaningful subtleties seen on individual maps may be obscured with group averagi ng approaches. Published by Elsevier Science Ireland Ltd.