title: Non-linear dynamics in parkinsonism.
abstract: Over the last 30 years, the functions (and dysfunctions) of the sensory-motor circuitry have been mostly conceptualized using linear modelizations which have resulted in two main models: the "rate hypothesis" and the "oscillatory hypothesis." In these two models, the basal ganglia data stream is envisaged as a random temporal combination of independent simple patterns issued from its probability distribution of interval interspikes or its spectrum of frequencies respectively. More recently, non-linear analyses have been introduced in the modelization of motor circuitry activities, and they have provided evidences that complex temporal organizations exist in basal ganglia neuronal activities. Regarding movement disorders, these complex temporal organizations in the basal ganglia data stream differ between conditions (i.e., parkinsonism, dyskinesia, healthy control) and are responsive to treatments (i.e., l-DOPA, deep brain stimulation). A body of evidence has reported that basal ganglia neuronal entropy (a marker for complexity/irregularity in time series) is higher in hypokinetic state. In line with these findings, an entropy-based model has been recently formulated to introduce basal ganglia entropy as a marker for the alteration of motor processing and a factor of motor inhibition. Importantly, non-linear features have also been identified as a marker of condition and/or treatment effects in brain global signals (EEG), muscular activities (EMG), or kinetic of motor symptoms (tremor, gait) of patients with movement disorders. It is therefore warranted that the non-linear dynamics of motor circuitry will contribute to a better understanding of the neuronal dysfunctions underlying the spectrum of parkinsonian motor symptoms including tremor, rigidity, and hypokinesia.
authors.affiliation: Department of Neurology, University of South Alabama , Mobile, AL , USA ; Division of System Neurophysiology, National Institute for Physiological Sciences , Okazaki , Japan.
authors.forename: Olivier
authors.initials: O
authors.lastname: Darbin
authors.affiliation: Department of Speech Pathology and Audiology, University of South Alabama , Mobile, AL , USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Adams
authors.affiliation: Department of Neurosurgery, University of South Alabama , Mobile, AL , USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Martino
authors.affiliation: Department of Neurology, University of South Alabama , Mobile, AL , USA.
authors.forename: Leslie
authors.initials: L
authors.lastname: Naritoku
authors.affiliation: Department of Neurology, University of South Alabama , Mobile, AL , USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Dees
authors.affiliation: Department of Neurology, University of South Alabama , Mobile, AL , USA.
authors.forename: Dean
authors.initials: D
authors.lastname: Naritoku
keywords: EEG; EMG; entropy; movement disorders; single unit