title: Somatotopy in the ipsilateral primary motor cortex.
abstract: Conflicting reports exist about the occurrence, reliability and localization of activation in the ipsilateral primary motor cortex (M1). We re-examined this issue with functional magnetic resonance imaging in 12 volunteers performing right hand, finger, wrist, elbow, foot and tongue movements in two separate sessions. Ipsilateral M1 activation was inconsistently and non-reliably present during all movements: in 54% of all hand, 50% elbow, 46% finger, 33% wrist, and in 17% of all foot experiments. When compared to contralateral M1, the volumes and maximum t-values were always smaller. The ipsilateral M1 body representation was somatotopically organized with coordinates similar to the contralateral M1. Finally, the presence of ipsilateral M1 activation depended on the global activation level in other motor-related areas, which was significantly increased, when ipsilateral M1 activation was detected.
authors.affiliation: Institute of Neuroradiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.forename: Gerard R
authors.initials: GR
authors.lastname: Crelier
authors.forename: Sabina Hotz
authors.initials: SH
authors.lastname: Boendermaker
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Hepp-Reymond
authors.forename: Spyros S
authors.initials: SS
authors.lastname: Kollias
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004550:Elbow / Q000502:physiology; D005260:Female; D005385:Fingers / Q000502:physiology; D005528:Foot / Q000502:physiology; D007839:Functional Laterality; D006225:Hand / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D014059:Tongue / Q000502:physiology; D014953:Wrist / Q000502:physiology