title: Reduction in subthalamic 8-35 Hz oscillatory activity correlates with clinical improvement in Parkinson's disease.
abstract: Strong synchronization of neuronal activity occurs in the 8-35 Hz band in the subthalamic nucleus (STN) of patients with Parkinson's disease (PD) and is evident as oscillatory local field potential (LFP) activity. To test whether such synchronization may contribute to bradykinesia and rigidity, we sought correlations between the suppression of synchronization at 8-35 Hz in STN and the reduction in Parkinsonism with levodopa. LFPs were recorded on and off medication from STN deep-brain stimulation electrodes in nine PD patients. LFP power was calculated over the frequencies of the most prominent spectral peak within the 8-35 Hz frequency band on each of 17 sides (off medication), and over the frequencies of any peak in the 60-90 Hz band, if present (seven sides, on medication). Levodopa-induced reduction of LFP power over these two frequency ranges was then correlated with improvement in motor impairment as assessed by the Unified Parkinson's Disease Rating Scale (UPDRS). The reduction in peak activity in the 8-35 Hz band with levodopa positively correlated with the improvement in the contralateral hemibody motor UPDRS score with levodopa (r = 0.811, P < 0.001) as well as with hemibody subscores of akinesia-rigidity (r = 0.835, P < 0.001), but not tremor. A trend for negative correlations was found between peak 60-90 Hz LFP power and UPDRS hemibody score, suggesting that positive correlations were relatively frequency-specific. Our results support a link between levodopa-induced improvements in bradykinesia and rigidity and reductions in population synchrony at frequencies < 35 Hz in the region of the STN in patients with PD.
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London WCIN 3BG, UK. a.kuhn@ion.ucl.ac.uk
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Kühn
authors.forename: Andreas
authors.initials: A
authors.lastname: Kupsch
authors.forename: Gerd-Helge
authors.initials: GH
authors.lastname: Schneider
authors.forename: Peter
authors.initials: P
authors.lastname: Brown
mesh_terms: D000200:Action Potentials; D000978:Antiparkinson Agents / Q000627:therapeutic use; D003344:Cortical Synchronization; D046690:Deep Brain Stimulation; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008875:Middle Aged; D009068:Movement; D010300:Parkinson Disease / Q000503:physiopathology* / Q000628:therapy; D020531:Subthalamic Nucleus / Q000503:physiopathology*
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa