INDIVIDUAL PATTERNS OF FUNCTIONAL REORGANIZATION IN THE HUMAN CEREBRAL-CORTEX AFTER CAPSULAR INFARCTION

We have previously shown bilateral activation of motor pathways and th e recruitment of additional motor areas in studies of groups of patien ts with recovery from motor stroke. We have now developed a new positr on emission tomographic technique to measure the changes in regional c erebral blood flow elicited during a motor task in individual patients , relative to the cerebral activation found in normal subjects. The pa tterns of cerebral activation in each of 8 individual patients with ca psular lesions of the pyramidal tract and complete recovery from hemip legia are described by comparison with the pattern found in a represen tative sample of 10 normal subjects. We found a large ventral extensio n of the hand field of the contralateral (sensori)motor cortex in all patients with lesions of the posterior limb of the internal capsule. G reater activation than in normal subjects was found in variable combin ations of the supplementary motor areas, the insula, the frontal operc ulum, and the parietal cortex. Structures belonging to motor pathways ipsilateral to the recovered limb were also more activated in the pati ents than in normal subjects. However, additional activation of the ip silateral (sensori)motor cortex was only found in the 4 patients who e xhibited associated movements of the unaffected hand when the recovere d hand performed the motor task. We conclude that recovery from motor stroke due to striatocapsular damage is associated with individually d ifferent patterns of functional reorganization of the brain. These pat terns are dependent on the site of the subcortical lesion and the soma totopic organization of the pyramidal tract, both of which may determi ne the precise potential for recovery of limb function following this type of brain injury.