Deep brain stimulation of the center median-parafascicular complex of the thalamus has efficient anti-parkinsonian action associated with widespread cellular responses in the basal ganglia network in a rat model of Parkinson's disease.

International audienceThe thalamic centromedian-parafascicular (CM/Pf) complex, mainly represented by Pf in rodents, is proposed as an interesting target for the neurosurgical treatment of movement disorders, including Parkinson's disease. In this study, we examined the functional impact of subchronic high-frequency stimulation (HFS) of Pf in the 6-hydroxydopamine-lesioned hemiparkinsonian rat model. Pf-HFS had significant anti-akinetic action, evidenced by alleviation of limb use asymmetry (cylinder test). Whereas this anti-akinetic action was moderate, Pf-HFS totally reversed lateralized neglect (corridor task), suggesting potent action on sensorimotor integration. At the cellular level, Pf-HFS partially reversed the dopamine denervation-induced increase in striatal preproenkephalin A mRNA levels, a marker of the neurons of the indirect pathway, without interfering with the markers of the direct pathway (preprotachykinin and preprodynorphin). Pf-HFS totally reversed the lesion-induced changes in the gene expression of cytochrome oxidase subunit I in the subthalamic nucleus, the globus pallidus, and the substantia nigra pars reticulata, and partially in the entopeduncular nucleus. Unlike HFS of the subthalamic nucleus, Pf-HFS did not induce per se dyskinesias and directly, although partially, alleviated L-3,4-dihydroxyphenylalanine (L-DOPA)-induced forelimb dyskinesia. Conversely, L-DOPA treatment negatively interfered with the anti-parkinsonian effect of Pf-HFS. Altogether, these data show that Pf-DBS, by recruiting a large basal ganglia circuitry, provides moderate to strong anti-parkinsonian benefits that might, however, be affected by L-DOPA. The widespread behavioral and cellular outcomes of Pf-HFS evidenced here demonstrate that CM/Pf is an important node for modulating the pathophysiological functioning of basal ganglia and related disorders

Characterization of acoustic materials at arbitrary incidence angle using sound field synthesis

Standardized methods for measuring sound absorption such as the impedance tube and reverberation chamber methods are limited to normal or diffuse incidence, respectively. Two research axes have been generally followed in the literature to develop alternative techniques, the first one focusing on the measurement part, that is from the two-microphone technique to the use of microphone arrays or pressure-velocity sensors. The second axis focuses on the excitation part with for instance the use of sound field synthesis techniques. Since acoustic impedance and sound absorption coefficient of materials are classically defined under normal and oblique plane wave excitation, synthesizing an “ideal” plane wave using a loudspeaker array would allow measuring these acoustics quantities using a simple microphone pair. In this article, the effect of the different parameters of a loudspeaker array on acoustic plane waves reproduction on a material’s surface is first numerically studied. Then, numerical and experimental results for the estimation of both impedance and absorption coefficients are reported. These results show that sound field synthesis allows to characterize a material for arbitrary incidence angles over a wide frequency range, thus offering an alternative method to standard techniques and an improvement over existing works

How I explore: ventricular arrhythmias in athletes

peer reviewedRÉSUMÉ : La mise en évidence d’une arythmie ventriculaire ou de symptômes évocateurs chez un sportif justifie toujours une mise au point cardiologique minutieuse. Il convient de définir la nature de l’arythmie ventriculaire dont le pronostic est lié à la présence d’une cardiopathie sous-jacente. En l’absence de cette dernière, au terme d’un bilan diagnostique complet, le pronostic de l’arythmie est généralement bon et ne justifie pas l’arrêt systématique de la compétition. Dans le cas contraire, celle-ci est proscrite. En fonction de la cardiopathie identifiée, une pratique sportive adaptée peut être éventuellement autorisée à titre récréatif. Dans cet article, nous revoyons les différentes arythmies ventriculaires susceptibles d’être rencontrées chez l’athlète ainsi que leur mise au point diagnostique et leur prise en charge.How I explore : ventricular arrhythmhmias in athletes SUMMARY : Documented ventricular tachyarrhythmias or related symptoms need meticulous cardiac investigations. The mechanism of ventricular arrhythmia must be defined. The prognosis is related to underlying cardiac electrical or structural disorders. In the absence of cardiovascular abnormalities, the prognosis is good. No disqualification to competitive activity is required in most cases. Assessment of the risk of sudden death remains a continuing challenge in athletes. This article reviews the diagnostic and therapeutic approaches of ventricular arrhythmias encountered in trained athletes

Measurement of subwoofers with the field separation method: comparison of p- p and p-v formulations

International audienceMeasurement of very low frequency sources is rather difficult to perform because very few testing rooms remain anechoic in the 10-100 Hz frequency range. To overcome this problem, the field separation method has been proposed a few years ago. This technique consists in measuring two acoustic quantities on a closed surface surrounding the tested source. To take advantages of spherical harmonic functions, the measurement surface should be spherical. The acoustic quantities can either be acoustic pressure measured on two concentric (half-) spheres or pressure and velocity measured on a (half-) sphere. Then, by using spherical harmonic expansions, contribution from the subwoofer is separated from reflections on the walls of the testing rooms to recover half or free space conditions. This paper focuses on the choice of the measured data set. Simulations are performed using p-p and p-v data approaches. The effect of microphone spacing for the double pressure layer formulation will be investigated. Finally, measurement results obtained on different subwoofers, i.e., frequency response and directivity, will be shown to highlight simulation results

Clinical case of the month. Purulent pericarditis in a patient with pulmonary sarcoidosis

peer reviewedWe report the case of a patient, suffering from pulmonary sarcoidosis, who developed a purulent pericarditis complicated with a cardiac tamponade. The widespread use of antibiotics has progressively reduced the number of purulent pericarditis. However, it remains a serious disease that has to be rapidly diagnosed to be treated timely. We will review the required tests for the diagnosis and the treatment of this pathology that leads to death otherwise. The link with pulmonary sardoidosis is uncertain