title: Source analysis of the magnetic field evoked during self-paced finger movements.
abstract: 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.
authors.affiliation: Department of Neurosurgery, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan. mamishim@ntmc.hosp.go.jp
authors.forename: Maki
authors.initials: M
authors.lastname: Niimi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ohira
authors.forename: Takenori
authors.initials: T
authors.lastname: Akiyama
authors.forename: Kenji
authors.initials: K
authors.lastname: Hiraga
authors.forename: Yousei
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Masato
authors.initials: M
authors.lastname: Ochiai
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fukunaga
authors.forename: Masahito
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kawase
mesh_terms: 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