title: Dopaminergic therapy promotes lateralized motor activity in the subthalamic area in Parkinson's disease.
abstract: Treatment of patients with Parkinson's disease with levodopa has profound effects on both movement and the pattern of movement-related reactivity in the subthalamic nucleus (STN), as reflected in the local field potential (LFP). The most striking change is the promotion of reactivity in the gamma frequency band, but it remains unclear whether the latter is itself a pathological feature, possibly associated with levodopa induced dyskinesias, or is primarily physiological. Gamma band reactivity in the cerebral cortex of humans without Parkinson's disease occurs contralateral to movement, so we posited that lateralization of subcortical gamma reactivity should occur following levodopa if the latter restores a more physiological pattern in patients with Parkinson's disease. Accordingly, we studied movement-related changes in STN LFP activity in 11 Parkinson's disease patients (age 59 +/- 2.7 years, three females) while they performed ipsi- and contralateral self-paced joystick movements ON and OFF levodopa. A bilaterally symmetrical gamma band power increase occurred around movement onset in the OFF state. Following levodopa this feature became significantly more pronounced in the subthalamic region contralateral to movement. The physiological nature of this asymmetric pattern of gamma reactivity was confirmed in the STN of two tremor patients without Parkinson's disease. Although levodopa treatment in the Parkinson's disease patients did not lead to lateralization of power suppression at lower frequencies (8-30 Hz), it did increase the degree of power suppression. These findings suggest that dopaminergic therapy restores a more physiological pattern of reactivity in the STN of patients with Parkinson's disease.
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, UK.
authors.forename: Alexandros G
authors.initials: AG
authors.lastname: Androulidakis
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Kühn
authors.forename: Chiung Chu
authors.initials: CC
authors.lastname: Chen
authors.forename: Patric
authors.initials: P
authors.lastname: Blomstedt
authors.forename: Florian
authors.initials: F
authors.lastname: Kempf
authors.forename: Andreas
authors.initials: A
authors.lastname: Kupsch
authors.forename: Gerd-Helge
authors.initials: GH
authors.lastname: Schneider
authors.forename: Louise
authors.initials: L
authors.lastname: Doyle
authors.forename: Patricia
authors.initials: P
authors.lastname: Dowsey-Limousin
authors.forename: Marwan I
authors.initials: MI
authors.lastname: Hariz
authors.forename: Peter
authors.initials: P
authors.lastname: Brown
mesh_terms: D000328:Adult; D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use*; D046690:Deep Brain Stimulation / Q000379:methods; D004567:Electrodes, Implanted; D004569:Electroencephalography; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000187:drug effects*; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D020531:Subthalamic Nucleus / Q000187:drug effects* / Q000503:physiopathology
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa