title: Neuromagnetic gamma-band activity in the primary and secondary somatosensory areas.
abstract: To evaluate the gamma-band activity related to somatosensory processing, we recorded neuromagnetic signals from seven healthy subjects. The source power changes evoked by electrical stimulation of the median nerve were estimated with synthetic aperture magnetometry (SAM). Source power in the low gamma band (40 Hz) decreased in the contralateral primary somatosensory cortex (SI) for a few hundred milliseconds (i.e. middle and long latency) and then increased inversely. Source power in the high gamma band (70-90 Hz) increased simultaneously both in the contralateral SI and contra/ipsilateral secondary somatosensory cortex (SII) in 80-180 ms. These results suggest that low and high gamma oscillations work under independent mechanisms during somatosensory processing. In particular, high gamma oscillations may play an essential role in making a functional connection between SI and SII.
authors.affiliation: Department of Basic Laboratory Science, Osaka University Graduate School of Medicine, Suita, Japan. aya-i@sahs.med.osaka-u.ac.jp
authors.forename: Aya
authors.initials: A
authors.lastname: Ihara
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hirata
authors.forename: Keiko
authors.initials: K
authors.lastname: Yanagihara
authors.forename: Hirotomo
authors.initials: H
authors.lastname: Ninomiya
authors.forename: Katsumi
authors.initials: K
authors.lastname: Imai
authors.forename: Ryouhei
authors.initials: R
authors.lastname: Ishii
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Osaki
authors.forename: Kotoe
authors.initials: K
authors.lastname: Sakihara
authors.forename: Hiromi
authors.initials: H
authors.lastname: Izumi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Imaoka
authors.forename: Amami
authors.initials: A
authors.lastname: Kato
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yoshimine
authors.forename: Shiro
authors.initials: S
authors.lastname: Yorifuji
mesh_terms: D000328:Adult; D001683:Biological Clocks / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013003:Somatosensory Cortex / Q000502:physiology*