Neuromagnetic gamma-band activity in the primary and secondary somatosensory areas.
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.
Ihara
Aya
A
Department of Basic Laboratory Science, Osaka University Graduate School of Medicine, Suita, Japan. aya-i@sahs.med.osaka-u.ac.jp
Hirata
Masayuki
M
Yanagihara
Keiko
K
Ninomiya
Hirotomo
H
Imai
Katsumi
K
Ishii
Ryouhei
R
Osaki
Yasuhiro
Y
Sakihara
Kotoe
K
Izumi
Hiromi
H
Imaoka
Hiroyuki
H
Kato
Amami
A
Yoshimine
Toshiki
T
Yorifuji
Shiro
S
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*