Source analysis of the magnetic field evoked during self-paced finger movements.
OBJECTIVE
The aim of this study is to investigate a source of cortical magnetic fields evoked by index finger movements.


METHODS
We analysed both movement-related cortical fields (MRCFs) and somatosensory-evoked fields (SEFs) by single equivalent current dipole (ECD) method in six healthy subjects. Dipole locations were superimposed on MR images of each individual subject.


RESULTS
The first component after finger movement (movement-evoked field I, MEFI) was observed in all subjects. The dipole of MEFI was oriented posteriorly, and was located on the posterior wall of the central sulcus of the hemisphere contralateral to the movement. The SEFs showed three major components: N20m, P30m and P60m. The dipoles of P30m and P60m were orientated posteriorly, similarly to the MEFI dipole, while that of N20m was orientated anteriorly. The dipole location of MEFI was closely located to P60m, not to N20m and P30m. The mean location of the MEFI dipole was significantly (p<0.05) superior to N20m.


CONCLUSIONS
These findings suggest that MEFI would be generated in the sensory area (area 3b) affected by multiple afferents and activities, and that the source of the MEFI is not identical to that of the N20m component.
Niimi
Maki
M
Department of Neurosurgery, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan. mamishim@ntmc.hosp.go.jp
Ohira
Takayuki
T
Akiyama
Takenori
T
Hiraga
Kenji
K
Kaneko
Yousei
Y
Ochiai
Masato
M
Fukunaga
Atsushi
A
Kobayashi
Masahito
M
Kawase
Takeshi
T
D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000294:innervation*; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D009068:Movement / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology