title: Modulation of human cortical rolandic rhythms during natural sensorimotor tasks.
abstract: We studied modulation of cortical neuromagnetic rhythms in association with left and right median nerve stimulation, during rest, finger movements, and passive tactile hand stimulation, in seven healthy, right-handed adults. In the rest condition, the amplitude of the rhythmic sensorimotor activity decreased immediately after the median nerve stimuli and increased above the prestimulus level within 0.4 s afterward, especially in the 7- to 25-Hz band. The rebound occurred 100-300 ms earlier for 20 (7-15)-than for 10 (15-25)-Hz activity. Suppressions and rebounds were strongest in the contralateral sensorimotor hand area for the 20-Hz, but not for the 10-Hz, activity. The maximum rebound was on average 22-34% stronger in the left than in the right hemisphere. Active exploration of objects abolished rebounds of both 10- and 20-Hz signals in the contralateral hemisphere and markedly diminished them ipsilaterally. Finger movements without touching an object and passive tactile stimulation produced a weaker effect. The sensorimotor rhythms thus show a characteristic suppression and subsequent rebound after electrical median nerve stimulation. The rebound is left-hemisphere dominant in right-handed subjects and its suppression reveals bilateral cortical activation during both motor tasks and passive tactile stimulation, especially for explorative finger movements.
authors.affiliation: Brain Research Unit, Helsinki University of Technology, Espoo, Finland. stephan@neuro.hut.fi
authors.forename: S
authors.initials: S
authors.lastname: Salenius
authors.forename: A
authors.initials: A
authors.lastname: Schnitzler
authors.forename: R
authors.initials: R
authors.lastname: Salmelin
authors.forename: V
authors.initials: V
authors.lastname: Jousmäki
authors.forename: R
authors.initials: R
authors.lastname: Hari
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology