Regional cerebral blood flow changes in cortex and basal ganglia during voluntary movements in normal human volunteers

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Abstract
The structures in the human brain that contribute to the organization of voluntary movements were localized and whether measurement of the regional cerebral blood flow (rCBF) following inhalation of a positron-emitting isotope, 77Kr, could be used for functional mapping of the brain in normal human individuals were determined. The rCBF was measured in transverse sections of the brains of 10 young volunteers with a positron-emission tomograph (PET). Two measurements were taken, 1 control study with the subjects resting and 1 study when subjects unilaterally executed a sequence of ballistic movements with their fingers. The mean rCBF in gray matter structures during rest varied between 69-83 ml .cntdot. 100 g-1 per min. The highest rCBF occurred in the superior mesial frontal region. When the motor sequence was executed, the rCBF increased bilaterally in the supplementary motor areas (30%), the premotor areas (10%), the parietal opercula (9%), and the paracentral lobules (20%), but only in the contralateral motor hand area (28%). Subcortically there was a strong contralateral increase (30%) and a weaker ipsilateral increase (14%) in the globus pallidus. There were more moderate increases bilaterally in the head of the caudate nucleus (11-15%), the putamen (15%) and the thalamic-subthalamic region (10%). Apart from the sensorimotor hand area, the only statistically significant difference between the contralateral and ipsilateral rCBF increases was found in the globus pallidus. This bihemispheric activation probably signifies a bilateral elaboration of the motor program, although the movements were strictly unilateral. The difference in pallidal activation was attributed to pallidal output to the contralateral motor hand area only. In each subject the same pattern appeared on the side contralateral to the movements: the rCBF in the supplementary motor area, premotor area, head of caudate nucleus, putamen, pallidum lower thalamus and motor hand area increased in the proportions 3:1:1:5:1.5:3:1:3, respectively. This indicates that the amounts of synaptic changes between these structures are fixed in the above proportions during execution of the motor sequence.