title: Altered corticomotor representation in patients with Parkinson's disease.
abstract: In 6 patients with Parkinson's disease (PD) and 6 age-matched controls, transcranial magnetic stimulation was applied at 56 regions over the motor cortex and premotor cortex of each hemisphere, with the first dorsal interosseous (FDI) muscle of both hands activated at 15% maximum voluntary contraction during stimulation. For each site, motor evoked potential (MEP) landmarks were recovered, including MEP amplitude, MEP onset latency, and silent period duration. Scaled MEP amplitudes were used to construct individual cortical maps of the FDI muscles. The maps revealed an anterior displacement of the muscle representation in PD patients. This anterior shift over motor cortical areas may reflect increased contributions of corticocortical connections between motor cortex and premotor cortical areas, possibly enhanced by the visual feedback aspect of the task. These alterations may reflect adaptations to the impairments in striatocortical circuits in PD.
authors.affiliation: Human Motor Control Laboratory, School of Psychology, University of Tasmania, Hobart, Australia.
authors.forename: Florian A
authors.initials: FA
authors.lastname: Kagerer
authors.forename: Jeff J
authors.initials: JJ
authors.lastname: Summers
authors.forename: Winston D
authors.initials: WD
authors.lastname: Byblow
authors.forename: Bruce
authors.initials: B
authors.lastname: Taylor
mesh_terms: D000368:Aged; D003342:Corpus Striatum / Q000503:physiopathology; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008280:Magnetics / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009415:Nerve Net / Q000503:physiopathology; D009434:Neural Pathways / Q000503:physiopathology; D010300:Parkinson Disease / Q000503:physiopathology*; D017397:Prefrontal Cortex / Q000503:physiopathology; D012720:Severity of Illness Index; D012886:Skull