title: Generators of movement-related cortical potentials: fMRI-constrained EEG dipole source analysis.
abstract: To clarify the precise location and timing of the mo tor cortical activation in voluntary movement, dipole source analysis integrating multiple constraints wa conducted for the movement-related cortical potentia (MRCP). Six healthy subjects performed single self paced extensions of the right index finger at about 15-intervals during EEG and event-related fMRI acquisi tions. EEG was recorded from 58 scalp electrodes, and fMRI of the entire brain was obtained every 2.6 s. Coordinates of the two methods were coregistered us ing anatomical landmarks. During dipole source mod eling, a realistic three-layer head model was used as a volume conductor. To identify the number of uncorre lated source s in the MRCP, principal component (PC analysis was performed, which was consistent with the existence of six sources in the left (Lt SM1) and right (Rt SMI) sensorimotor and medial frontocentral (MFC) areas. After dipoles were seeded at the acti vated spots revealed by fMRI, dipole orientations were fixed based on the interpretation of the topography of distribution of the PC. The strength of the six dipoles (three dipoles in Lt SMI, two in Rt SMI, and one in MFC) was then computed over time. Within the bilat eral SM1, activation of the precentral gyrus occurs bilaterally with similar strength from -1.2 s, followed by that of the precentral bank from -0.5 s with con tralateral preponderance. Subsequently, the postcen tral bank becomes active only on the contralateral side at 0.1 s after movement. Activation of the MFC shows timing similar to that of the bilateral precentral gyri These deduced patterns of activation are consis tent with previous studies of electrocorticography in humans.
authors.affiliation: Human Motor Control Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1428, USA.
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Toma
authors.forename: Takahiro
authors.initials: T
authors.lastname: Matsuoka
authors.forename: Ilka
authors.initials: I
authors.lastname: Immisch
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Mima
authors.forename: Daniel
authors.initials: D
authors.lastname: Waldvogel
authors.forename: Benjamin
authors.initials: B
authors.lastname: Koshy
authors.forename: Takashi
authors.initials: T
authors.lastname: Hanakawa
authors.forename: Holly
authors.initials: H
authors.lastname: Shill
authors.forename: Mark
authors.initials: M
authors.lastname: Hallett
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography / Q000706:statistics & numerical data; D004576:Electromyography; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D013997:Time Factors