''Gating'' of human short-latency somatosensory evoked cortical responses during execution of movement. A high resolution electroencephalography study

The present study aimed at investigating gating of median nerve somatosenso ry evoked cortical responses (SECRs), estimated during executed continuous complex ipsilateral and contralateral sequential finger movements. SECRs we re modeled with an advanced high resolution electroencephalography technolo gy that dramatically improved spatial details of the scalp recorded somatos ensory evoked potentials. Integration with magnetic resonance brain images allowed us to localize different SECRs within cortical areas. The working h ypothesis was that the gating effects were time varying and could different ly influence SECRs, Maximum statistically significant (p < 0.01) time-varyi ng gating (magnitude reduction) of the short-latency SECRs modeled in the c ontralateral primary motor and somatosensory and supplementary motor areas was computed during the executed ipsilateral movement. The gating effects w ere stronger on the modeled SECRs peaking 30-45 ms (N30-P30, N32, P45-N45) than 20-26 ms (P20-N20, P22, N26) post-stimulus. Furthermore, the modeled S ECRs peaking 30 ms post-stimulus (N30-P30) were significantly increased in magnitude during the executed contralateral movement. These results may del ineate a distributed cortical sensorimotor system responsible for the gatin g effects on SECRs. This system would be able to modulate activity of SECR generators, based on the integration of afferent somatosensory inputs from the stimulated nerve with outputs related to the movement execution. (C) 19 99 Elsevier Science B.V. All rights reserved.