Frequency-dependent spatial distribution of human somatosensory evoked neuromagnetic fields.
Using synthetic aperture magnetometry (SAM), we examined the spatial distribution of frequency changes in magnetoencephalography signal rhythms on individual magnetic resonance images following somatosensory stimulation. SAM is a novel statistical spatial filtering method that uses an adaptive beamformer. Electrical stimulation of the right median nerve demonstrated high-frequency event-related synchronization (ERS) in the 50-200-Hz range, consistently localized in the contralateral primary sensorimotor area in all subjects (n=7). Event-related desynchronization (ERD) was demonstrated in the 8-13, 13-25 and 25-50-Hz ranges bilaterally in the area surrounding the central sulcus. The differences in the spatial distribution as well as the frequency bands between ERS and ERD suggest that ERS and ERD reflect the responses of different cell assemblies rather than a frequency shift of the same cell assembly.
Hirata
Masayuki
M
Department of Neurosurgery, Osaka University Graduate School of Medicine, E6 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Kato
Amami
A
Taniguchi
Masaaki
M
Ninomiya
Hirotomo
H
Cheyne
Douglas
D
Robinson
Stephen E
SE
Maruno
Motohiko
M
Kumura
Eiji
E
Ishii
Ryouhei
R
Hirabuki
Norio
N
Nakamura
Hironobu
H
Yoshimine
Toshiki
T
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology*; D001931:Brain Mapping; D003337:Corpus Callosum / Q000502:physiology; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology