title: Hypersynchrony despite pathologically reduced beta oscillations in patients with Parkinson's disease: a pharmaco-magnetoencephalography study.
abstract: Parkinson's disease (PD) is a progressive debilitating neurodegenerative disorder clinically manifest by motor, posture and gait abnormalities. Human neurophysiological studies recording local field potentials within the subthalamic nucleus and scalp-based electroencephalography have shown pathological beta synchrony throughout the basal ganglia-thalamic-cortical motor network in PD. Notably, suppression of this pathological beta synchrony by dopamine replacement therapy or deep-brain stimulation has been associated with improved motor function. However, due to the invasive nature of these studies, it remains unknown whether this "pathological beta" is actually stronger than that observed in healthy demographically matched controls. We used magnetoencephalography to investigate neuronal synchrony and oscillatory amplitude in the beta range and lower frequencies during the resting state in patients with PD and a matched group of patients without neurological disease. Patients with PD were studied both in the practically defined drug "OFF" state, and after administration of dopamine replacements. We found that beta oscillatory amplitude was reduced bilaterally in the primary motor regions of unmedicated patients with PD compared with controls. Administration of dopaminergic medications significantly increased beta oscillatory activity, thus having a normalizing effect. Interestingly, we also found significantly stronger beta synchrony (i.e., hypersynchrony) between the primary motor regions in unmedicated patients with PD compared with controls, and that medication reduced this coupling which is in agreement with the intraoperative studies. These results are consistent with the known functionality of the basal ganglia-thalamic-cortical motor circuit and the likely consequences of beta hypersynchrony in the subthalamic nucleus of patients with PD.
authors.affiliation: Department of Psychology, University of Nebraska, Omaha, Nebraska; Center for Magnetoencephalography, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Heinrichs-Graham
authors.affiliation: Center for Magnetoencephalography, University of Nebraska Medical Center, Omaha, Nebraska; Department of Physical Therapy, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Max J
authors.initials: MJ
authors.lastname: Kurz
authors.affiliation: Center for Magnetoencephalography, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Becker
authors.affiliation: Neurology Consultants of Nebraska, Omaha, Nebraska;
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Santamaria
authors.affiliation: Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska; and.
authors.forename: Howard E
authors.initials: HE
authors.lastname: Gendelman
authors.affiliation: Center for Magnetoencephalography, University of Nebraska Medical Center, Omaha, Nebraska; Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska; and Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, Nebraska Tony.W.Wilson@gmail.com.
authors.forename: Tony W
authors.initials: TW
authors.lastname: Wilson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000978:Antiparkinson Agents / Q000494:pharmacology; D001611:Beta Rhythm / Q000187:drug effects; D003344:Cortical Synchronization / Q000187:drug effects; D015259:Dopamine Agents / Q000494:pharmacology; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000187:drug effects / Q000503:physiopathology*; D010300:Parkinson Disease / Q000503:physiopathology*
chemical_list: D000978:Antiparkinson Agents; D015259:Dopamine Agents
keywords: MEG; cortex; magnetoencephalography; oscillations; resting state