Dynamics of mu-rhythm suppression caused by median nerve stimulation: a magnetoencephalographic study in human subjects.
We studied event-related desynchronization (ERD) of the 8-13 Hz rhythm (mu rhythm) of the primary somatosensory cortex (SI) caused by contra- and ipsilateral median-nerve stimulation. We used whole-head magnetoencephalography (MEG) and wavelet analysis together with our newly developed color-coded single-trial ERD display. The somatosensory stimuli suppressed mu rhythm at both contra- and ipsilateral SI, but the attenuation was clearly lateralized, being at least 20% stronger contra- than ipsilaterally. Moreover, repeated stimulation significantly reduced mu-rhythm ERD in the ipsilateral but not in the contralateral hemisphere in the course of the experiment. The observed lateralization is in agreement with the classical concept of a dominant role of the contralateral hemisphere in the processing of somatosensory information. The strong ipsilateral ERD in the beginning of the experiment may reflect the presence of non-specific arousal-like activation, which attenuates toward the end of the experiment.
Nikouline
V V
VV
BioMag Laboratory, Medical Engineering Centre, Helsinki University Central Hospital, P.O. Box 442, FIN-00029 HUS, Helsinki, Finland. vadim@oliivi.huch.fi
Linkenkaer-Hansen
K
K
Wikström
H
H
Kesäniemi
M
M
Antonova
E V
EV
Ilmoniemi
R J
RJ
Huttunen
J
J
D000328:Adult; D000704:Analysis of Variance; D004558:Electric Stimulation / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D018709:Statistics, Nonparametric