Biology subjects

Degos, B.

Publications and source records attributed to Degos, B..

3 recordsLinked to original sources

bioRxiv2022

Video-based automated analysis of MDS-UPDRS III parameters in Parkinson disease

BackgroundAmong motor symptoms of Parkinsons disease (PD), including rigidity and resting tremor, bradykinesia is a mandatory feature to define the parkinsonian syndrome. MDS-UPDRS III is the worldwide reference scale to evaluate the parkinsonian motor impairment, especially bradykinesia. However, MDS-UPDRS III constitutes an agent-based score making reproducible measurements and follow-up challenging. ObjectivesUsing a deep learning approach, we developed a tool to compute an objective score of bradykinesia based on the gold-standard MDS-UPDRS III. MethodsIn the Movement Disorder unit of Avicenne University Hospital, we acquired a large database of videos of parkinsonian patients performing MDS-UPDRS III protocols. We applied two deep learning algorithms to detect a two-dimensional (2D) skeleton of the hand composed of 21 predefined points, and transposed it into a three-dimensional (3D) skeleton. ResultsWe developed a 2D and 3D automated analysis tool to study the evolution of several key parameters during the protocol repetitions of the MDS-UPDRS III. Scores from 2D automated analysis showed a significant correlation with gold-standard ratings of MDS-UPDRS III, measured with coefficients of determination for the tapping (0.609) and hand movements (0.701) protocols using decision tree algorithms. The individual correlations of the different parameters measured with MDS-UPDRS III scores carry meaningful information and are consistent with MDS-UPDRS III guidelines. ConclusionWe developed a deep learning-based tool to reliably score and analyze bradykinesia for parkinsonian patients.

neuroscience↗

bioRxiv2021

Cerebellar stimulations prevent Levodopa-induced dyskinesia in mice and normalize brain activity

Chronic Levodopa therapy, the gold-standard treatment of Parkinsons Disease (PD), leads to the emergence of involuntary movements, called levodopa-induced dyskinesia (LID). Cerebellar stimulations have been shown to decrease LID severity in PD patients. Here, in order to determine how cerebellar stimulations induce LID alleviation, we performed daily short trains of optogenetic stimulations of Purkinje cells (PC) in freely moving mice. We demonstrated that these stimulations are sufficient to suppress LID or even prevent their development. This symptomatic relief is accompanied by the normalization of aberrant neuronal discharge in the cerebellar nuclei, the motor cortex and the parafascicular thalamus. Inhibition of the cerebello-parafascicular pathway counteracted the beneficial effect of cerebellar stimulations. Moreover, cerebellar stimulations reversed plasticity in D1 striatal neurons and normalized the overexpression of FosB, a transcription factor causally linked to LID. These findings demonstrate LID alleviation and prevention by daily PC stimulations, which restore the function of a wide brain motor network, and may be valuable for LID treatment.

neuroscience↗

bioRxiv2018

Opto-activation of cortical somatostatin interneurons alleviates parkinsonian symptoms

Deep brain stimulation of the subthalamic nucleus is a symptomatic treatment of Parkinsons disease but benefits only to a minority of patients due to stringent eligibility criteria. To investigate new targets for less invasive therapies, we aimed at elucidating key mechanisms supporting deep brain stimulation efficiency. Here, using in vivo electrophysiology, optogenetics and modeling, we found that subthalamic stimulation normalizes pathological hyperactivity of motor cortex pyramidal cells, while concurrently activating somatostatin and inhibiting parvalbumin interneurons. In vivo opto-activation of cortical somatostatin interneurons alleviates motor symptoms in a parkinsonian mouse model. A mathematical model highlights how the decrease in pyramidal neurons activity can restore information processing capabilities. Overall, these results demonstrate that activation of cortical somatostatin interneurons may constitute a less invasive alternative than subthalamic stimulation.\n\nOne-sentence SummaryDeep brain stimulation recruits cortical somatostatin interneurons, and their opto-activation is beneficial in Parkinsons.

neuroscience↗