title: Hemispheric asymmetries of the premotor cortex are task specific as revealed by disruptive TMS during bimanual versus unimanual movements.
abstract: The premotor cortex (PMC) is functionally lateralized, such that the left PMC is activated for unimanual movements of either hand, whereas the right PMC is particularly active during complex bimanual movements. Here we ask the question whether the high activation of right PMC in the bimanual context reflects either hemispheric specialization or handedness. Left- and right-handed subjects performed a bimanual antiphase tapping task at different frequencies while transcranial magnetic stimulation (TMS) was used to temporarily disrupt left versus right PMC during complex bimanual movements. For both handedness groups, more disruptions were induced when TMS was applied over the motor nondominant PMC than over the motor dominant PMC or when sham-TMS was used. In a second experiment, right-handers performed complex unimanual tapping with either hand, while TMS was applied to the PMC in both hemispheres. The novel result was that the high susceptibility of the motor nondominant PMC was specific to the bimanual context, indicating that hemispheric asymmetries of the PMC depend on the bimanual versus unimanual nature of the motor task. We hypothesize that asymmetries of PMC involvement in bimanual control reflect interhemispheric interactions, whereby the motor nondominant PMC appears to prevent motor cross talk arising from the dominant hemisphere.
authors.affiliation: Motor Control Laboratory, Research Center for Movement Control and Neuroplasticity, Department of Biomedical Kinesiology, Group Biomedical Sciences, K.U. Leuven, Tervuursevest 101, Heverlee, Belgium.
authors.forename: Femke E
authors.initials: FE
authors.lastname: van den Berg
authors.forename: Stephan P
authors.initials: SP
authors.lastname: Swinnen
authors.forename: Nicole
authors.initials: N
authors.lastname: Wenderoth
mesh_terms: D000293:Adolescent; D004576:Electromyography; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult