Alterations in brain connectivity underlying beta oscillations in Parkinsonism.
Rosalyn J. Moran,Nicolas Mallet,Vladimir Litvak,Raymond J. Dolan,Peter J. Magill,Karl J. Friston,Peter Brown +6 more
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TLDR
A novel perspective is provided on how altered connectivity in basal ganglia-thalamocortical circuits reflects a balance between pathogenesis and compensation, and predicts potential new therapeutic targets to overcome dysfunctional oscillations.Abstract:
Cortico-basal ganglia-thalamocortical circuits are severely disrupted by the dopamine depletion of Parkinson's disease (PD), leading to pathologically exaggerated beta oscillations. Abnormal rhythms, found in several circuit nodes are correlated with movement impairments but their neural basis remains unclear. Here, we used dynamic causal modelling (DCM) and the 6-hydroxydopamine-lesioned rat model of PD to examine the effective connectivity underlying these spectral abnormalities. We acquired auto-spectral and cross-spectral measures of beta oscillations (10-35 Hz) from local field potential recordings made simultaneously in the frontal cortex, striatum, external globus pallidus (GPe) and subthalamic nucleus (STN), and used these data to optimise neurobiologically plausible models. Chronic dopamine depletion reorganised the cortico-basal ganglia-thalamocortical circuit, with increased effective connectivity in the pathway from cortex to STN and decreased connectivity from STN to GPe. Moreover, a contribution analysis of the Parkinsonian circuit distinguished between pathogenic and compensatory processes and revealed how effective connectivity along the indirect pathway acquired a strategic importance that underpins beta oscillations. In modelling excessive beta synchrony in PD, these findings provide a novel perspective on how altered connectivity in basal ganglia-thalamocortical circuits reflects a balance between pathogenesis and compensation, and predicts potential new therapeutic targets to overcome dysfunctional oscillations.read more
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New insights into the relationship between dopamine, beta oscillations and motor function
Ned Jenkinson,Peter Brown +1 more
TL;DR: It is proposed that the levels of beta oscillations provide a measure of the likelihood that a new voluntary action will need to be actuated, and that the resulting modulation of beta activity is predictive, enabling the appropriate prospective resourcing and preparation of potential actions.
Journal ArticleDOI
Cerebral causes and consequences of parkinsonian resting tremor: a tale of two circuits?
TL;DR: Clinical and pathological differences between tremor-dominant and non-tremor Parkinson's disease subtypes are described, a newly proposed ‘dimmer-switch model’ is discussed that explains tremor as resulting from the combined actions of two circuits: the basal ganglia that trigger tremor episodes and the cerebello-thalamo-cortical circuit that produces the tremor.
Journal ArticleDOI
Dichotomous Organization of the External Globus Pallidus
Nicolas Mallet,Benjamin R. Micklem,Pablo Henny,Matthew Brown,Claire Williams,J. Paul Bolam,Kouichi Nakamura,Peter J. Magill +7 more
TL;DR: It is concluded that GPe exhibits several core components of a dichotomous organization as fundamental as that in striatum, and two populations of GPe neuron together orchestrate activities across all basal ganglia nuclei in a cell-type-specific manner.
Journal ArticleDOI
Bursts of beta oscillation differentiate postperformance activity in the striatum and motor cortex of monkeys performing movement tasks
TL;DR: It is shown that brief bursts of oscillation are responsible for virtually all beta-band activity in healthy monkeys, and it is suggested that the timing and duration of these bursts are critical parameters for network function.
Journal ArticleDOI
Connectivity Changes Underlying Spectral EEG Changes during Propofol-Induced Loss of Consciousness
Mélanie Boly,Rosalyn J. Moran,Michael Murphy,Pierre Boveroux,Marie-Aurélie Bruno,Quentin Noirhomme,Didier Ledoux,Vincent Bonhomme,Jean-François Brichant,Giulio Tononi,Steven Laureys,Karl J. Friston +11 more
TL;DR: A direct effect of propofol on cortical dynamics is suggested and the importance of recurrent corticocortical communication in the maintenance of consciousness is emphasized and the best model for explaining spectral changes across the three states involved changes in corticothalamic interactions.
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