title: An fMRI study of the lateralization of motor cortex activation in acallosal patients.
abstract: Transcranial magnetic stimulation (TMS) studies have suggested that callosal afferents may mediate inhibition of the ipsilateral motor cortex (IMC) during unilateral hand movements. To test this concept, we used fMRI to determine whether acallosal patients have increased IMC activation with either complex or simple unilateral finger movements. Neither the localization of motor cortical regions activated, the volumes of activation, or the relative hemispheric lateralization of activations were different between the patients and normal controls. The potential callosal inhibitory pathway identified by TMS therefore does not appear to contribute to the interhemispheric suppression of physiologically relevant activations in the motor cortex as measured by fMRI.
authors.affiliation: Centre for Functional Magnetic Resonance Imaging of the Brain, Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital, UK.
authors.forename: H
authors.initials: H
authors.lastname: Reddy
authors.forename: M
authors.initials: M
authors.lastname: Lassonde
authors.forename: N
authors.initials: N
authors.lastname: Bemasconi
authors.forename: A
authors.initials: A
authors.lastname: Bemasconi
authors.forename: P M
authors.initials: PM
authors.lastname: Matthews
authors.forename: F
authors.initials: F
authors.lastname: Andermann
authors.forename: D L
authors.initials: DL
authors.lastname: Amold
mesh_terms: D000328:Adult; D061085:Agenesis of Corpus Callosum; D001931:Brain Mapping; D003337:Corpus Callosum / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000033:anatomy & histology / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D009434:Neural Pathways / Q000002:abnormalities* / Q000033:anatomy & histology / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology