title: Altered plasticity of the human motor cortex in Parkinson's disease.
abstract: Interventional paired associative stimulation (IPAS) to the contralateral peripheral nerve and cerebral cortex can enhance the primary motor cortex (M1) excitability with two synchronously arriving inputs. This study investigated whether dopamine contributed to the associative long-term potentiation-like effect in the M1 in Parkinson's disease (PD) patients. Eighteen right-handed PD patients and 11 right-handed age-matched healthy volunteers were studied. All patients were studied after 12 hours off medication with levodopa replacement (PD-off). Ten patients were also evaluated after medication (PD-on). The IPAS comprised a single electric stimulus to the right median nerve at the wrist and subsequent transcranial magnetic stimulation of the left M1 with an interstimulus interval of 25 milliseconds (240 paired stimuli every 5 seconds for 20 minutes). The motor-evoked potential amplitude in the right abductor pollicis brevis muscle was increased by IPAS in healthy volunteers, but not in PD patients. IPAS did not affect the motor-evoked potential amplitude in the left abductor pollicis brevis. The ratio of the motor-evoked potential amplitude before and after IPAS in PD-off patients increased after dopamine replacement. Thus, dopamine might modulate cortical plasticity in the human M1, which could be related to higher order motor control, including motor learning.
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, Japan.
authors.forename: Yoshino
authors.initials: Y
authors.lastname: Ueki
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Mima
authors.forename: Mamdouh Ali
authors.initials: MA
authors.lastname: Kotb
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sawada
authors.forename: Hidemoto
authors.initials: H
authors.lastname: Saiki
authors.forename: Akio
authors.initials: A
authors.lastname: Ikeda
authors.forename: Tahamina
authors.initials: T
authors.lastname: Begum
authors.forename: Faruque
authors.initials: F
authors.lastname: Reza
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagamine
authors.forename: Hidenao
authors.initials: H
authors.lastname: Fukuyama
mesh_terms: D000368:Aged; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D010300:Parkinson Disease / Q000503:physiopathology*; D011897:Random Allocation; D013223:Statistics as Topic; D050781:Transcranial Magnetic Stimulation
chemical_list: D004298:Dopamine