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See detailOscillations in the basal ganglia: illustration of a cellular effect at the network level
Dethier, Julie ULg; Drion, Guillaume; Franci, Alessio et al

Poster (2013, June)

Parkinson’s disease (PD) is a neuro-degenerative pathology affecting the basal ganglia (BG), a set of small subcortical nervous system nuclei. The hallmark of the disease is a dopaminergic denervation of ... [more ▼]

Parkinson’s disease (PD) is a neuro-degenerative pathology affecting the basal ganglia (BG), a set of small subcortical nervous system nuclei. The hallmark of the disease is a dopaminergic denervation of the striatum, al- tering information patterns along movement-related ganglia-mediated path- ways in the brain. Severe motor symptoms result from the pathological state: tremor at rest, bradykinesia, akinesia, and rigidity. The transition to the disease state correlates with a switch in the firing mode of the neurons in the BG, from tonic pacemaker activity to burst firing. At the network level, macro-electrode recordings reveal excessive oscillations in the beta (8- 30Hz) frequency band. The oscillations generation mechanism and their functional role remain under debate. We propose a network model where a cellular mechanism controls the dynamical state of the network. In our model, the oscillatory state impacts the neural information processing prop- erties of the network. The network model predicts that a single decrease of the dopaminergic level in the parkinsonnian condition switches the network into an abnormal oscillatory dynamical and globally insensitive state. The brief dopaminergic increase prior to voluntary movements suppresses beta oscillations to drive the network to a conductive state to sensory processing and cognition. [less ▲]

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See detailImpacts of a unicellular mechanism on network behaviors
Dethier, Julie ULg; Drion, Guillaume; Franci, Alessio et al

Conference (2013, March 26)

Parkinson’s disease (PD) is a neurodegenerative disorder af- fecting the basal ganglia (BG), a set of small subcortical nervous system nuclei. The hallmark of the disease is a dopaminergic denervation of ... [more ▼]

Parkinson’s disease (PD) is a neurodegenerative disorder af- fecting the basal ganglia (BG), a set of small subcortical nervous system nuclei. The hallmark of the disease is a dopaminergic denervation of the striatum—the input stage of the BG—altering information patterns along movement- related ganglia-mediated pathways in the brain. Severe mo- tor symptoms result from the pathological state: tremor at rest, bradykinesia—the slowness and impaired scaling of voluntary movement—and akinesia—the poverty of volun- tary movements. It is still unclear how dopamine depletion causes those motor symptoms. Experimental studies have shown that abnormally synchronized oscillatory activities— rhythmic bursting activity at the unicellular level and beta frequency band (from 8 to 30Hz) oscillations at the network level—emerge in PD at multiple levels of the BG-cortical loops and correlate with motor symptoms. The mechanisms underlying these pathological beta oscillations remain elu- sive. We propose that a cellular mechanism generates burst- ing activities and beta band oscillations at the network level. [less ▲]

Detailed reference viewed: 65 (11 ULg)
See detailA unicellular mechanism to switch a network behavior from tonic activity to synchronous oscillations
Dethier, Julie ULg; Drion, Guillaume; Franci, Alessio et al

Poster (2012, October 08)

Parkinson’s disease (PD) is a neurodegenerative disorder affecting the basal ganglia (BG), a set of small subcortical nervous system nuclei. The hallmark of the disease is a dopaminergic denervation of ... [more ▼]

Parkinson’s disease (PD) is a neurodegenerative disorder affecting the basal ganglia (BG), a set of small subcortical nervous system nuclei. The hallmark of the disease is a dopaminergic denervation of the input stage of the BG, altering information patterns along movement-related ganglia-mediated pathways in the brain, inducing therefore movement disorders such as tremor at rest, bradykinesia, akinesia, and rigidity. It is still unclear how dopamine depletion causes those motor symptoms. Experimental studies have shown that abnormally synchronized oscillatory activities- rhythmic bursting activity at the neurocellular level and beta frequency band oscillations at the network level-emerge in PD at multiple levels of the BG-cortical loops and are correlated with motor symptoms. We propose a computational model of the BG using a novel unicellular mechanism to explain the induction of bursting activity and beta band oscillations in the network. We show how a single change in the dopaminergic level at the input stage of the BG can switch the model from its physiological state to the pathological state. This computational model also proposes a simple mechanism for high-frequency deep brain stimulations. [less ▲]

Detailed reference viewed: 44 (13 ULg)