0000000000020907
AUTHOR
Paolo Stanzione
Cerebellar magnetic stimulation decreases levodopa-induced dyskinesias in Parkinson disease
BACKGROUND: The neural mechanisms and the circuitry involved in levodopa-induced dyskinesia (LID) are still partially obscure. LID can be considered the consequence of an abnormal pattern or code of activity that originates and is conveyed from the basal ganglia to the thalamus and the cortical motor areas. However, not only striatothalamocortical motor circuits but also other interconnected pathways could be implicated in its pathogenesis. METHODS: In a series of experiments, we applied repetitive transcranial magnetic stimulation (rTMS) over the lateral cerebellum in a group of patients with advanced Parkinson disease, to investigate whether modulation of cerebellothalamocortical circuits…
rTMS of supplementary motor area modulates therapy-induced dyskinesias in Parkinson disease
The neural mechanisms and circuitry involved in levodopa-induced dyskinesia are unclear. Using repetitive transcranial magnetic stimulation (rTMS) over the supplementary motor area (SMA) in a group of patients with advanced Parkinson disease, the authors investigated whether modulation of SMA excitability may result in a modification of a dyskinetic state induced by continuous apomorphine infusion. rTMS at 1 Hz was observed to markedly reduce drug-induced dyskinesias, whereas 5-Hz rTMS induced a slight but not significant increase.
High-frequency rTMS improves time perception in Parkinson disease.
Patients with Parkinson disease (PD) are impaired in time processing. The authors investigated the effects of high-frequency (5 Hz) repetitive transcranial magnetic stimulation (rTMS) in patients with PD performing a time reproduction task. The authors found significant improvement in time processing induced by rTMS when trains were applied over the right dorsolateral prefrontal cortex (DLPFC) but not over the supplementary motor area, suggesting that the circuit involving the basal ganglia and the DLPFC might constitute the neural network subserving time perception.
Memory for time intervals is impaired in left hemi-Parkinson patients.
The basal ganglia have been proposed as one of the neural correlates of timekeeping functions. Both encoding and memory retrieval components for time perception are impaired in Parkinson's disease (PD). The aim of our study was to investigate in hemi-Parkinsonian patients the existence of a specific alteration in memory for time depending on the affected side, to better understand the contribution of the left or right basal ganglia circuits in different components of time perception. Right and left hemi-PD patients performed a time reproduction task in which they were required to reproduce in the same session short (5 s) and long (15 s) time intervals, in off- and on-therapy condition. Whil…
Subthalamic deep brain stimulation improves time perception in Parkinson's disease.
Alterations in temporal estimation have been observed in Parkinson's disease (PD) and have been associated with dopaminergic dysfunction. To investigate whether deep brain stimulation might reverse these abnormalities in PD, patients treated with electrode implantation for subthalamic deep brain stimulation were required to reproduce time intervals in different experimental conditions (off deep brain stimulation/off therapy, on deep brain stimulation/off therapy, on therapy/off deep brain stimulation). Patients treated with deep brain stimulation in off deep brain stimulation/off therapy displayed the anomalous pattern of responses typically observed in PD. When subthalamic deep brain stimu…
Acute inactivation of the medial forebrain bundle imposes oscillations in the SNr: a challenge for the 6-OHDA model?
It has been recently shown that the substantia nigra pars reticulata (SNr) of 6-hydroxydopamine (6-OHDA)-lesioned rats, under urethane anaesthesia, manifests a prominent low frequency oscillation (LFO) of around 1Hz, synchronized with cortical slow wave activity (SWA). Nevertheless, it is poorly understood whether these electrophysiological alterations are correlated only with severe dopamine depletion or may also play a relevant pathogenetic role in the early stages of the dopamine denervation. Hence, here we recorded SNr single units and electrocorticogram (ECoG) in two models of dopamine denervation: (i) acute dopamine denervated rats, obtained by injection of tetrodotoxin (TTX), (ii) ch…