title: Electrocorticography reveals beta desynchronization in the basal ganglia-cortical loop during rest tremor in Parkinson's disease.
abstract: The pathophysiology of rest tremor in Parkinson's disease (PD) is not well understood, and its severity does not correlate with the severity of other cardinal signs of PD. We hypothesized that tremor-related oscillatory activity in the basal-ganglia-thalamocortical loop might serve as a compensatory mechanism for the excessive beta band synchronization associated with the parkinsonian state. We recorded electrocorticography (ECoG) from the sensorimotor cortex and local field potentials (LFP) from the subthalamic nucleus (STN) in patients undergoing lead implantation for deep brain stimulation (DBS). We analyzed differences in measures of network synchronization during epochs of spontaneous rest tremor, versus epochs without rest tremor, occurring in the same subjects. The presence of tremor was associated with reduced beta power in the cortex and STN. Cortico-cortical coherence and phase-amplitude coupling (PAC) decreased during rest tremor, as did basal ganglia-cortical coherence in the same frequency band. Cortical broadband gamma power was not increased by tremor onset, in contrast to the movement-related gamma increase typically observed at the onset of voluntary movement. These findings suggest that the cortical representation of rest tremor is distinct from that of voluntary movement, and support a model in which tremor acts to decrease beta band synchronization within the basal ganglia-cortical loop.
authors.affiliation: Department of Biomedical Engineering, Columbia University, USA. Electronic address: salman.qasim@columbia.edu.
authors.forename: Salman E
authors.initials: SE
authors.lastname: Qasim
authors.affiliation: Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA. Electronic address: Coralie.Dehemptinne@ucsf.edu.
authors.forename: Coralie
authors.initials: C
authors.lastname: de Hemptinne
authors.affiliation: Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA. Electronic address: Nicole.Swann@ucsf.edu.
authors.forename: Nicole C
authors.initials: NC
authors.lastname: Swann
authors.affiliation: Department of Neurology, University of California San Francisco, San Francisco, CA, USA. Electronic address: Svjetlana.Miocinovic@ucsf.edu.
authors.forename: Svjetlana
authors.initials: S
authors.lastname: Miocinovic
authors.affiliation: Department of Neurology, University of California San Francisco, San Francisco, CA, USA. Electronic address: Jill.Ostrem@ucsf.edu.
authors.forename: Jill L
authors.initials: JL
authors.lastname: Ostrem
authors.affiliation: Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA. Electronic address: Philip.Starr@ucsf.edu.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Starr
mesh_terms: D000368:Aged; D001611:Beta Rhythm; D003344:Cortical Synchronization; D000069280:Electrocorticography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D010300:Parkinson Disease / Q000150:complications*; D066191:Sensorimotor Cortex / Q000503:physiopathology*; D020531:Subthalamic Nucleus / Q000503:physiopathology*; D014202:Tremor / Q000209:etiology / Q000503:physiopathology*
keywords: Basal ganglia; Deep brain stimulation (DBS); Electrocorticography (ECoG); Parkinson's disease; Tremor