Ipsilateral hemisphere activation during motor and sensory tasks.

PURPOSE To compare activation of the ipsilateral cerebral hemisphere during tactile sensory and motor tasks involving the right and left hands.

METHODS Eight volunteers had functional MR imaging to measure the extent of cerebral hemisphere activation during a motor task and sensory task involving each hand. Hemispheric indexes (left hemisphere activation minus right hemisphere activation)/(left hemisphere activation plus right hemisphere activation) were computed for each hand and each task. The indexes for two tasks and the two hands were compared.

RESULTS The left-hand motor tasks activated the ipsilateral hemisphere in right handers significantly more than did the right-hand tasks. Motor tasks produced a greater activation of the ipsilateral hemisphere than did the sensory tasks. No significant differences were found between the hemispheric indexes for the right-hand and left-hand sensory tasks.

CONCLUSION This study confirms findings of a previous study, showing that the left hemisphere is active in left-hand motor tasks. Activation of the ipsilateral hemisphere is significantly less pronounced during sensory tasks than during motor tasks.