Functional reorganization of the brain in recovery from striatocapsular infarction in man

Abstract

We used positron emission tomography (PET) to study organizational changes in the functional anatomy of the brain in 10 patients following recovery from striatocapsular motor strokes. Comparisons of regional cerebral blood flow maps at rest between the patients and 10 normal subjects revealed significantly lower regional cerebral blood flow in the basal ganglia, thalamus, sensorimotor, insular, and dorsolateral prefrontal cortices, in the brainstem, and in the ipsilateral cerebellum in patients, contralateral to the side of the recovered hand. These deficits reflect the distribution of dysfunction caused by the ischemic lesion. Regional cerebral blood flow was significantly increased in the contralateral posterior cingulate and premotor cortices, and in the caudate nucleus ipsilateral to the recovered hand. During the performance of a motor task by the recovered hand, patients activated the contralateral cortical motor areas and ipsilateral cerebellum to the same extent as did normal subjects. However, activation was greater than in normal subjects in both insulae; in the inferior parietal (area 40), prefrontal and anterior cingulate cortices; in the ipsilateral premotor cortex and basal ganglia; and in the contralateral cerebellum. The pattern of cortical activation was also abnormal when the unaffected hand, contralateral to the hemiplegia, performed the task. We showed that bilateral activation of motor pathways and the recruitment of additional sensorimotor areas and of other specific cortical areas are associated with recovery from motor stroke due to striatocapsular infarction. Activation of anterior and posterior cingulate and prefrontal cortices suggests that selective attentional and intentional mechanisms may be important in the recovery process. Our findings suggest that there is considerable scope for functional plasticity in the adult human cerebral cortex.

Ipsilateral Actions of Feline Corticospinal Tract Neurons on Limb Motoneurons

“…tion might involve ipsilateral actions of intact corticospinal neurons, as indicated by both clinical observations (Weiller et al, 1992;Feydy et al, 2002;Strens et al, 2003) and behavioral experiments in animals (Kucera and Wiesendanger, 1985;DarianSmith et al, 1996;Whishaw et al, 1998;Liu and Rouiller, 1999;Pettersson et al, 2000). If these ipsilateral actions, which are normally much weaker than contralateral actions, can be enhanced at spinal and/or bulbar levels, then this represents a new opportunity to restore function.…”

Motor cortical mapping of proximal upper extremity muscles following spinal cord injury

“…12,13 Using positron emission tomography Weiller et al 12 showed that the recruitment of additional sensorimotor areas was associated with motor recovery. Clinically then, changes to motor maps may be the substrate for functional recovery in paretic limbs although this has not been demonstrated using transcranial magnetic stimulation.…”

Synaptogenesis in the Contralateral Primary Motor Area after Focal Brain Infarction in Rats

“…Clinical studies of stroke patients using PET or MRI have revealed that the undamaged hemisphere is activated when hemiplegic limbs are moved 4,5). Consistent with these findings, a study in rats showed positive synaptophysin immunostaining in the cerebral cortex of the undamaged hemisphere 1) .…”

“…Plastic changes occur in the undamaged hemisphere as well as in the damaged hemisphere [1][2][3] . Clinical studies in which stroke patients were examined by positron emission tomography (PET) or magnetic resonance imaging (MRI) show that the undamaged hemisphere is activated when hemiplegic limbs are moved 4,5) . In animal studies, proteins important for neuronal plasticity were found to increase in the cerebral cortex of the undamaged hemisphere following brain injuries 1,6) .…”