The Parkinsonian Subthalamic Network: Measures of Power, Linear, and Non-linear Synchronization and their Relationship to L-DOPA Treatment and OFF State Motor Severity.
In this paper we investigated the dopaminergic modulation of neuronal interactions occurring in the subthalamic nucleus (STN) during Parkinson's disease (PD). We utilized linear measures of local and long range synchrony such as power and coherence, as well as Detrended Fluctuation Analysis for Phase Synchrony (DFA-PS)- a recently developed non-linear method that computes the extent of long tailed autocorrelations present in the phase interactions between two coupled signals. Through analysis of local field potentials (LFPs) taken from the STN we seek to determine changes in the neurodynamics that may underpin the pathophysiology of PD in a group of 12 patients who had undergone surgery for deep brain stimulation. We demonstrate up modulation of alpha-theta (5-12 Hz) band power in response to L-DOPA treatment, whilst low beta band power (15-20 Hz) band-power is suppressed. We also find evidence for significant local connectivity within the region surrounding STN although there was evidence for its modulation via administration of L-DOPA. Further to this we present evidence for a positive correlation between the phase ordering of bilateral STN interactions and the severity of bradykinetic and rigidity symptoms in PD. Although, the ability of non-linear measures to predict clinical state did not exceed standard measures such as beta power, these measures may help identify the connections which play a role in pathological dynamics.
Centre for Mathematics and Physics in the Life Sciences and Experimental Biology, UCLLondon, UK; Wellcome Trust Centre for Neuroimaging, UCL Institute of NeurologyLondon, UK.
Timothy
T
West
Department of Neurology, National Hospital for Neurology and NeurosurgeryLondon, UK; Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, UCLLondon, UK.
Simon
S
Farmer
Centre for Computational Neuroscience and Robotics, University of SussexFalmer, UK; UCL Great Ormond Street Institute of Child Health, UCLLondon, UK.
Luc
L
Berthouze
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL London, UK.
Ashwani
A
Jha
Department of Neurology, University Medical Center Groningen, University of Groningen Groningen, Netherlands.
Martijn
M
Beudel
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL London, UK.
Thomas
T
Foltynie
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL London, UK.
Patricia
P
Limousin
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL London, UK.
Ludvic
L
Zrinzo
Nuffield Department of Clinical Neurosciences, John Radcliffe HospitalOxford, UK; Medical Research Council Brain Network Dynamics Unit, University of OxfordOxford, UK.
Peter
P
Brown
Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology London, UK.
Vladimir
V
Litvak
Parkinson's disease; coherence; connectivity; criticality; deep brain stimulation (DBS); detrended fluctuation analysis; synchronization