Objective
To investigate cortical reorganization of the brain during voluntary activities of the hand in patients with subcortical cerebral infarction.

Method
Twelve patients with first-ever subcortical brain lesion causing hemiparesis had been evaluated with functional MRI. Bilateral hand clenching was done to test voluntary hand activities. Recovery period ranged from 2 to 36 months.

Results
During the unaffected hand movement, activation of contralateral primary sensorimotor cortex (SMC) were recorded in all cases and supplmentary motor area (SMA) in 1 case. The affected hand movement showed activation of the cotralateral SMC in all cases, ipsilateral SMC in 4 cases, SMA in 4 cases and contralateral prefrontal area in 2 cases. As for the contralateral SMC, affected hand movement showed more increased activation than the unaffected. For the bilateral SMC activation during movement of the affected hand, contralateral SMC activation was greater than the ipsilateral.

Conclusion
Ipsilateral activation of the SMC, SMA, prefrontal area and increased activation of the contralateral SMC during affected hand movement suggest that these may play an important role in the reorganization of sensory and motor system in stroke patients with subcortical lesion. Functional MRI studies of patients who recovered from subcortical stroke provide evidence for several process that may be related to restoration of neurologic function.