Brain activation pattern according to exercise complexity: a functional MRI study.

The aim of this study was to compare the areas of brain activation between complex and simple exercises in a unimanual hand and to assess the possibility of an exercise task for paretic hands following stroke. The subjects included 11 healthy right-handed volunteers. The complex exercise was a wooden ball rotation task with the unimanual hand and the simple exercise was a hand grasp task performed during a functional MRI scan. Stronger activation of the left primary sensorimotor cortex, the left premotor area, and the ipsilateral cerebellum emerged when the complex movement was performed. Ipsilateral activity was located in the primary sensory cortex and premotor area, and contralateral activity was shown in the left cerebellum. These results suggest that a unimanual ball rotation task may be appropriate for rehabilitation of a movable paretic hand in an early stage of stroke recovery, which should provide motor and sensory input using external stimuli, while the simple motor task may appropriate in a compensatory stage, and should inhibit the ipsilateral activity due to maladaptive plasticity.