title: Evidence for a 7- to 9-Hz "sigma" rhythm in the human SII cortex.
abstract: Electrical activity of the human brain features several rhythmical components which can be readily studied with whole-scalp neuromagnetometers. We describe a new 7- to 9-Hz "sigma" rhythm in the human second somatosensory cortex, distinct from both the mu rhythm of the primary sensorimotor cortex and the tau rhythm of the supratemporal auditory cortex. Sigma shows rate-selective responsiveness to rhythmical median nerve stimulation and is enhanced by stimulation at the rhythm's dominant frequency. Single stimuli may trigger several periods of the rhythm. The functional significance of the sigma rhythm remains to be investigated.
authors: Brain Research Unit, Helsinki University of Technology, Espoo, FIN-02015 HUT, Finland.
authors: L
authors: L
authors: Narici
authors: N
authors: N
authors: Forss
authors: V
authors: V
authors: Jousmäki
authors: M
authors: M
authors: Peresson
authors: R
authors: R
authors: Hari
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation; D004594:Electrophysiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008475:Median Nerve / Q000502:physiology; D010507:Periodicity; D013003:Somatosensory Cortex / Q000502:physiology*