Functional magnetic resonance imaging of the human motor cortex before andafter whole-hand afferent electrical stimulation

Electrical stimulation of the whole hand using a mesh-glove has been shown to improve volitional movement of the hand and arm, and decrease muscle hyp ertonia after hemispherical stroke in patients who have reached a recovery plateau, The goal of this study was to investigate the effect of stimulatio n of the nerve afferents of the hand on brain cortical activity elicited by whole-hand subthreshold stimulation for sensation in humans with intact ne rvous systems. Brain cortical activity in 6 healthy subjects (30-45 years) was studied using blood oxygenation level-dependent functional Magnetic Res onance Imaging during a test motor task, finger-to-thumb tapping and after 20 minutes of mesh-glove stimulation of the resting hand prior to performan ce of an identical motor task, to test the changes in the conditioned motor task established after 20 minutes of mesh-glove stimulation. Fifteen conti guous echo-planar sequences parallel to the bicommissural plane were acquir ed for functional magnetic resonance, Post-processing of image data include d correction of motion artefacts and calculation of correlation coefficient s between the signal intensity of pixels during rest and finger tapping and a rectangular reference wave function, The functional Magnetic Resonance I maging examinations revealed a signal increase in the primary and secondary motor and somatosensory areas when comparing the number of activated pixel s during test and conditioned motor tasks. Our preliminary study indicated that change occurred in a definite pattern in the region of the regional ce rebral blood flow of the brain cortex after mesh-glove whole-hand stimulati on at the subthreshold level for sensation. We assumed that this increase i n regional cerebral blood flow also reflected augmented neuronal activity.