CEREBRAL HEMODYNAMICS DURING SENSORIMOTOR ACTIVATION IN HUMANS

We studied the time course and magnitude of cerebral blood flow velocity (CBFV) changes in the middle cerebral artery (MCA) and the regional cerebral blood flow (rCBF) in the MCA territory during stimulation of the left sensorimotor cortex. Healthy right-handed male subjects were examined during performance of right-hand finger movement sequences, vibratory stimulation, and somatosensory discrimination. In somatosensory discrimination there were significant increases of the mean CBFV (4.8 +/- 9.9 cm/s; P < 0.01) and the mean rCBF (10.2 +/- 4.2 ml.100 g(-1).min(-1); P < 0.01), whereas no significant changes of the mean CBFV and rCBF occurred in finger movement sequences or vibratory stimulation. During all stimulation sessions the mean CBFV changes increased rapidly and reached a first maximum 3.3 +/- 0.3 s after stimulation onset. Simultaneous measurements of relative mean CBFV changes in both MCAs revealed left-right differences during voluntary finger movement sequences (left MCA, 14.3 +/- 10.6%; right MCA, 0.9 +/- 11.6%; P < 0.001) corresponding to a higher mean rCBF change in the left MCA territory. In the two tasks involving finger movements there was an increase of the respiratory rates (4.3 +/- 3.8 breaths/min; P < 0.05) and the pulse rates (11.6 +/- 5.5 beats/ min; P < 0.05), respectively. Our data demonstrate a correspondence of mean CBFV and rCBF changes evoked by sensorimotor activation in the human brain. Furthermore, cerebral hemodynamic changes related to motor activity are accompanied by cardiorespiratory effects.