Supporting Cells Eliminate Dying Sensory Hair Cells to Maintain Epithelial Integrity in the Avian Inner Ear

Epithelial homeostasis is essential for sensory transduction in the auditory and vestibular organs of the inner ear, but how it is maintained during trauma is poorly understood. To examine potential repair mechanisms, we expressed beta-actin-enhanced green fluorescent protein (EGFP) in the chick inner ear and used live-cell imaging to study how sensory epithelia responded during aminoglycoside-induced hair cell trauma. We found that glial-like supporting cells used two independent mechanisms to rapidly eliminate dying hair cells. Supporting cells assembled an actin cable at the luminal surface that extended around the pericuticular junction and constricted to excise the stereocilia bundle and cuticular plate from the hair cell soma. Hair bundle excision could occur within 3 min of actin-cable formation. After bundle excision, typically with a delay of up to 2-3 h, supporting cells engulfed and phagocytosed the remaining bundle-less hair cell. Dual-channel recordings with beta-actin-EGFP and vital dyes revealed phagocytosis was concurrent with loss of hair cell integrity. We conclude that supporting cells repaired the epithelial barrier before hair cell plasmalemmal integrity was lost and that supporting cell activity was closely linked to hair cell death. Treatment with the Rho-kinase inhibitor Y-27632 did not prevent bundle excision but prolonged phagocytic engulfment and resulted in hair cell corpses accumulating within the epithelium. Our data show that supporting cells not only maintain epithelial integrity during trauma but suggest they may also be an integral part of the hair cell death process itself

Linear Mixing Models for Active Listening of Music Productions in Realistic Studio Conditions

International audienceThe mixing/demixing of audio signals as addressed in the signal processing literature (the "source separation" problem) and the music production in studio remain quite separated worlds. Scienti c audio scene analysis rather focuses on "natural" mixtures and most often uses linear (convolutive) models of point sources placed in the same acoustic space. In contrast, the sound engineer can mix musical signals of very di erent nature and belonging to di erent acoustic spaces, and exploits many audio e ects including non-linear processes. In the present paper we discuss these di erences within the strongly emerging framework of active music listening, which is precisely at the crossroads of these two worlds: it consists in giving to the listener the ability to manipulate the di erent musical sources while listening to a musical piece. We propose a model that allows the description of a general studio mixing process as a linear stationary process of "generalized source image signals" considered as individual tracks. Such a model can be used to allow the recovery of the isolated tracks while preserving the professional sound quality of the mixture. A simple addition of these recovered tracks enables the end-user to recover the full-quality stereo mix, while these tracks can also be used for, e.g., basic remix / karaoke / soloing and re-orchestration applications

Regulation of otic neurosensory specification by Notch and Wnt signalling: insights from RNA-seq screenings in the embryonic chicken inner ear

The Notch and Wnt signalling pathways play key roles in the formation of inner ear sensory organs, but little is known about their transcriptional effectors and targets in this context. Here, we perturbed Notch and Wnt activities in the embryonic chicken otic vesicle using pharmacological treatment or in ovo electroporation of plasmid DNA, and used RNA-Seq to analyse the resulting changes in gene expression. Compared to pharmacological treatments, in ovo electroporation changed the expression of fewer genes, a likely consequence of the variability and mosaicism of transfection. The pharmacological inhibition of Notch activity induced a rapid change in the expression of known effectors of this pathway and genes associated with neurogenesis, consistent with a switch towards an otic neurosensory fate. The Wnt datasets contained many genes associated with a neurosensory biological function, confirming the importance of this pathway for neurosensory specification in the otocyst. Finally, the results of a preliminary gain-of-function screening of selected transcription factors and Wnt signalling components suggest that the endogenous programs of otic neurosensory specification are very robust, and in general unaffected by the overexpression of a single factor. Altogether this work provides new insights into the effectors and candidate targets of the Notch and Wnt pathways in the early developing inner ear and could serve as a useful reference for future functional genomics experiments in the embryonic avian inner ear

Jean-Martin Charcot’s role in the 19th century study of music aphasia

Jean-Martin Charcot (1825–93) was a well-known French neurologist. Although he is widely recognized for his discovery of several neurological disorders and his research into aphasia, Charcot’s ideas about how the brain processes music are less well known. Charcot discussed the music abilities of several patients in the context of his ‘Friday Lessons’ on aphasia, which took place at the Salpêtrière Hospital in Paris in 1883–84. In his most comprehensive discussion about music, Charcot described a professional trombone player who developed difficulty copying music notation and playing his instrument, thereby identifying a new isolated syndrome of music agraphia without aphasia. Because the description of this case was published only in Italian by one of his students, Domenico Miliotti, there has been considerable confusion and under-acknowledgement of Charcot’s ideas about music and the brain. In this paper, we describe Charcot’s ideas regarding music and place them within the historical context of the growing interest in the neurological underpinnings of music abilities that took place in the 1880s

Recueil d'ouvrages curieux de mathematique et de mecanique, ou description du cabinet de monsieur Grollier de Serviere [Texto impreso] : avec des figures en taille douce

Sign.: a4, e4, i6, A-O4Port. a dos tintas con grab. xil.Las h. de grab. calc.: 'Daudet fecit'En h. a2 capital y cabecera grab. calc. con el escudo de armas del duque de Orleans: "Houat f." y en h. A1 cabecera grab. xil.: "P. le Sueur

Etudes in vivo et in vitro du potentiel régénératif de l'organe de Corti (recherche de facteurs moléculaires capables d'influencer ce potentiel)

MONTPELLIER-BU Médecine (341722104) / SudocMONTPELLIER-BU Médecine UPM (341722108) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

PHASE-BASED INFORMED SOURCE SEPARATION FOR ACTIVE LISTENING OF MUSIC

This paper presents an informed source separation technique of monophonic mixtures. Although the vast majority of the separation methods are based on the time-frequency energy of each source, we introduce a new approach using solely phase information to perform the separation. The sources are iteratively reconstructed using an adaptation of the Multiple Input Spectrogram Inversion (MISI) algorithm from Gunawan and Sen. The proposed method is then tested against conventional MISI and Wiener filtering on monophonic signals and oracle conditions. Results show that at the cost of a larger computation time, our method outperforms both MISI and Wiener filtering in oracle conditions with much higher objective quality even with phase quantization. 1

Procédé de traitement numérique sur un ensemble de pistes audio avant mixage

déposé aux noms du CNRS, de l'Institut Polytechnique de Grenoble et de l'Université Paris Diderot (Paris 7), étendu à l'international (WO 2013087638)Procédé de traitement numérique sur un ensemble de pistes audio avant mixag