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Catherine J C Weisz - One of the best experts on this subject based on the ideXlab platform.
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synaptic inhibition of medial olivocochlear Efferent Neurons by Neurons of the medial nucleus of the trapezoid body
The Journal of Neuroscience, 2020Co-Authors: Lester Torres Cadenas, Matthew J Fischl, Catherine J C WeiszAbstract:Medial olivocochlear (MOC) Efferent Neurons in the brainstem comprise the final stage of descending control of the mammalian peripheral auditory system through axon projections to the cochlea. MOC activity adjusts cochlear gain and frequency tuning, and protects the ear from acoustic trauma. The neuronal pathways that activate and modulate the MOC somata in the brainstem to drive these cochlear effects are poorly understood. Evidence suggests that MOC Neurons are primarily excited by sound stimuli in a three-neuron activation loop from the auditory nerve via an intermediate neuron in the cochlear nucleus. Anatomical studies suggest that MOC Neurons receive diverse synaptic inputs, but the functional effect of additional synaptic influences on MOC neuron responses is unknown. Here we use patch-clamp electrophysiological recordings from identified MOC Neurons in brainstem slices from mice of either sex to demonstrate that in addition to excitatory glutamatergic synapses, MOC Neurons receive inhibitory GABAergic and glycinergic synaptic inputs. These synapses are activated by electrical stimulation of axons near the medial nucleus of the trapezoid body (MNTB). Focal glutamate uncaging confirms MNTB Neurons as a source of inhibitory synapses onto MOC Neurons. MNTB Neurons inhibit MOC action potentials, but this effect depresses with repeat activation. This work identifies a new pathway of connectivity between brainstem auditory Neurons and indicates that MOC Neurons are both excited and inhibited by sound stimuli received at the same ear. The pathway depression suggests that the effect of MNTB inhibition of MOC Neurons diminishes over the course of a sustained sound. SIGNIFICANCE STATEMENT Medial olivocochlear (MOC) Neurons are the final stage of descending control of the mammalian auditory system and exert influence on cochlear mechanics to modulate perception of acoustic stimuli. The brainstem pathways that drive MOC function are poorly understood. Here we show for the first time that MOC Neurons are inhibited by Neurons of the MNTB, which may suppress the effects of MOC activity on the cochlea.
Bernd Fritzsch - One of the best experts on this subject based on the ideXlab platform.
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evolution and development of hair cell polarity and Efferent function in the inner ear
Brain Behavior and Evolution, 2014Co-Authors: Ulrike J Sienknecht, Christine Koppl, Bernd FritzschAbstract:The function of the inner ear critically depends on mechanoelectrically transducing hair cells and their afferent and Efferent innervation. The first part of this review presents data on the evolution and development of polarized vertebrate hair cells that generate a sensitive axis for mechanical stimulation, an essential part of the function of hair cells. Beyond the cellular level, a coordinated alignment of polarized hair cells across a sensory epithelium, a phenomenon called planar cell polarity (PCP), is essential for the organ's function. The coordinated alignment of hair cells leads to hair cell orientation patterns that are characteristic of the different sensory epithelia of the vertebrate inner ear. Here, we review the developmental mechanisms that potentially generate molecular and morphological asymmetries necessary for the control of PCP. In the second part, this review concentrates on the evolution, development and function of the enigmatic Efferent Neurons terminating on hair cells. We present evidence suggestive of Efferents being derived from motoNeurons and synapsing predominantly onto a unique but ancient cholinergic receptor. A review of functional data shows that the plesiomorphic role of the Efferent system likely was to globally shut down and protect the peripheral sensors, be they vestibular, lateral line or auditory hair cells, from desensitization and damage during situations of self-induced sensory overload. The addition of a dedicated auditory papilla in land vertebrates appears to have favored the separation of vestibular and auditory Efferents and specializations for more sophisticated and more diverse functions.
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transcription factor gata 3 alters pathway selection of olivocochlear Neurons and affects morphogenesis of the ear
The Journal of Comparative Neurology, 2001Co-Authors: Alar Karis, Illar Pata, Hikke J Van Doorninck, Frank Grosveld, Chris I De Zeeuw, Dominique Crapon De Caprona, Bernd FritzschAbstract:Patterning the vertebrate ear requires the coordinated expression of genes that are involved in morphogenesis, neurogenesis, and hair cell formation. The zinc finger gene GATA-3 is expressed both in the inner ear and in afferent and Efferent auditory Neurons. Specifically, GATA-3 is expressed in a population of Neurons in rhombomere 4 that extend their axons across the floor plate of rhombomere 4 (r4) at embryonic day 10 (E10) and reach the sensory epithelia of the ear by E13.5. The distribution of their cell bodies corresponds to that of the cell bodies of the cochlear and vestibular Efferent Neurons as revealed by labeling with tracers. Both GATA-3 heterozygous and GATA-3 null mutant mice show unusual axonal projections, such as misrouted crossing fibers and fibers in the facial nerve, that are absent in wild-type littermates. This suggests that GATA-3 is involved in the pathfinding of Efferent neuron axons that navigate to the ear. In the ear, GATA-3 is expressed inside the otocyst and the surrounding periotic mesenchyme. The latter expression is in areas of branching of the developing ear leading to the formation of semicircular canals. Ears of GATA-3 null mutants remain cystic, with a single extension of the endolymphatic duct and no formation of semicircular canals or saccular and utricular recesses. Thus, both the distribution of GATA-3 and the effects of null mutations on the ear suggest involvement of GATA-3 in morphogenesis of the ear. This study shows for the first time that a zinc finger factor is involved in axonal navigation of the inner ear Efferent Neurons and, simultaneously, in the morphogenesis of the inner ear.
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dii reveals a prenatal arrival of Efferents at the differentiating otocyst of mice
Hearing Research, 1993Co-Authors: Bernd Fritzsch, David H NicholsAbstract:Abstract We have reinvestigated the time of arrival of Efferent fibers at the developing otocyst of mice employing diffusion of the lipophilic dye DiI in fixed tissue. In contrast to almost all previous reports, our data indicate a prenatal arrival of Efferent fibers. A few Efferent fibers were found to enter the eighth nerve root at embryonic day (ED) 10 1 2 . Retrogradely labelled Efferent cell bodies were at this stage coextensive with those of the facial motor nucleus, but started to segregate by ED 12. In contrast to retrogradely labelled facial motor Neurons, labelled Efferent Neurons were bilaterally distributed in the hindbrain with a few projecting to both otocysts as early as ED 12. Anterograde labelling from the brain showed Efferent fibers in the vestibular ganglion by ED 11. Invasion of the future vestibular sensory epithelia started by ED 12. Growth cones of Efferent fibers had also reached the future cochlear sensory epithelium but invasion was only achieved by a few filopodia at this stage. The early arrival of Efferents at the future sensory epithelia demonstrated here may allow an as yet unexplored interaction of Efferent fibers with the proliferating and/or differentiating hair cells.
Peter S Distefano - One of the best experts on this subject based on the ideXlab platform.
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axonal transport of neurotrophins by visceral afferent and Efferent Neurons of the vagus nerve of the rat
The Journal of Comparative Neurology, 1998Co-Authors: Cinda J. Helke, K M Adryan, J Fedorowicz, H Zhuo, John S Park, Rory A J Curtis, H E Radley, Peter S DistefanoAbstract:The receptor-mediated axonal transport of [125I]-labeled neurotrophins by afferent and Efferent Neurons of the vagus nerve was determined to predict the responsiveness of these Neurons to neurotrophins in vivo. [125I]-labeled neurotrophins were administered to the proximal stump of the transected cervical vagus nerve of adult rats. Vagal afferent Neurons retrogradely transported [125I]neurotrophin-3 (NT-3), [125I]nerve growth factor (NGF), and [125I]neurotrophin-4 (NT-4) to perikarya in the ipsilateral nodose ganglion, and transganglionically transported [125I]NT-3, [125I]NGF, and [125I]NT-4 to the central terminal field, the nucleus tractus solitarius (NTS). Vagal afferent Neurons showed minimal accumulation of [125I]brain-derived neurotrophic factor (BDNF). In contrast, Efferent (parasympathetic and motor) Neurons located in the dorsal motor nucleus of the vagus and nucleus ambiguus retrogradely transported [125I]BDNF, [125I]NT-3, and [125I]NT-4, but not [125I]NGF. The receptor specificity of neurotrophin transport was examined by applying [125I]-labeled neurotrophins with an excess of unlabeled neurotrophins. The retrograde transport of [125I]NT-3 to the nodose ganglion was reduced by NT-3 and by NGF, and the transport of [125I]NGF was reduced only by NGF, whereas the transport of [125I]NT-4 was significantly reduced by each of the neurotrophins. The competition profiles for the transport of NT-3 and NGF are consistent with the presence of TrkA and TrkC and the absence of TrkB in the nodose ganglion, whereas the profile for NT-4 suggests a p75 receptor-mediated transport mechanism. The transport profiles of neurotrophins by Efferent vagal Neurons in the dorsal motor nucleus of the vagus and nucleus ambiguus are consistent with the presence of TrkB and TrkC, but not TrkA, in these nuclei. These observations describe the unique receptor-mediated axonal transport of neurotrophins in adult vagal afferent and Efferent Neurons and thus serve as a template to discern the role of specific neurotrophins in the functions of these visceral sensory and motor Neurons in vivo. J. Comp. Neurol. 393:102–117, 1998. Published 1998 Wiley-Liss, Inc.1
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Axonal transport of neurotrophins by visceral afferent and Efferent Neurons of the vagus nerve of the rat
The Journal of comparative neurology, 1998Co-Authors: Cinda J. Helke, K M Adryan, J Fedorowicz, H Zhuo, John S Park, Rory A J Curtis, H E Radley, Peter S DistefanoAbstract:The receptor-mediated axonal transport of [125I]-labeled neurotrophins by afferent and Efferent Neurons of the vagus nerve was determined to predict the responsiveness of these Neurons to neurotrophins in vivo. [125I]-labeled neurotrophins were administered to the proximal stump of the transected cervical vagus nerve of adult rats. Vagal afferent Neurons retrogradely transported [125I]neurotrophin-3 (NT-3), [125I]nerve growth factor (NGF), and [125I]neurotrophin-4 (NT-4) to perikarya in the ipsilateral nodose ganglion, and transganglionically transported [125I]NT-3, [125I]NGF, and [125I]NT-4 to the central terminal field, the nucleus tractus solitarius (NTS). Vagal afferent Neurons showed minimal accumulation of [125I]brain-derived neurotrophic factor (BDNF). In contrast, Efferent (parasympathetic and motor) Neurons located in the dorsal motor nucleus of the vagus and nucleus ambiguus retrogradely transported [125I]BDNF, [125I]NT-3, and [125I]NT-4, but not [125I]NGF. The receptor specificity of neurotrophin transport was examined by applying [125I]-labeled neurotrophins with an excess of unlabeled neurotrophins. The retrograde transport of [125I]NT-3 to the nodose ganglion was reduced by NT-3 and by NGF, and the transport of [125I]NGF was reduced only by NGF, whereas the transport of [125I]NT-4 was significantly reduced by each of the neurotrophins. The competition profiles for the transport of NT-3 and NGF are consistent with the presence of TrkA and TrkC and the absence of TrkB in the nodose ganglion, whereas the profile for NT-4 suggests a p75 receptor-mediated transport mechanism. The transport profiles of neurotrophins by Efferent vagal Neurons in the dorsal motor nucleus of the vagus and nucleus ambiguus are consistent with the presence of TrkB and TrkC, but not TrkA, in these nuclei. These observations describe the unique receptor-mediated axonal transport of neurotrophins in adult vagal afferent and Efferent Neurons and thus serve as a template to discern the role of specific neurotrophins in the functions of these visceral sensory and motor Neurons in vivo.
M C Brown - One of the best experts on this subject based on the ideXlab platform.
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synapses from medial olivocochlear branches in the inferior vestibular nucleus
The Journal of Comparative Neurology, 1996Co-Authors: Thane E Benson, M C BrownAbstract:Olivocochlear Neurons are auditory Efferent Neurons that convey information from the brainstem to the auditory periphery. With light and electron microscopy, using mice, we studied the central branches of medial olivocochlear Neurons that are given off to the inferior vestibular nucleus. At the level of the electron microscope, the branches form synapses. The synapses are asymmetric with round vesicles, suggesting that they are excitatory. The synapses are formed mainly onto neuronal dendrites. These dendrites have a large range of diameters, and they may emanate from several types of target Neurons. These results indicate that the inferior vestibular nucleus is an integrating center for vestibular, auditory, and other types of information, but the results do not fit with current theories about the function of the olivocochlear system. © 1996 Wiley-Liss, Inc.
Pierreyves Placais - One of the best experts on this subject based on the ideXlab platform.
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two independent mushroom body output circuits retrieve the six discrete components of drosophila aversive memory
Cell Reports, 2015Co-Authors: Emna Bouzaiane, Severine Trannoy, Lisa Scheunemann, Pierreyves PlacaisAbstract:Understanding how the various memory components are encoded and how they interact to guide behavior requires knowledge of the underlying neural circuits. Currently, aversive olfactory memory in Drosophila is behaviorally subdivided into four discrete phases. Among these, short- and long-term memories rely, respectively, on the γ and α/β Kenyon cells (KCs), two distinct subsets of the ∼2,000 Neurons in the mushroom body (MB). Whereas V2 Efferent Neurons retrieve memory from α/β KCs, the Neurons that retrieve short-term memory are unknown. We identified a specific pair of MB Efferent Neurons, named M6, that retrieve memory from γ KCs. Moreover, our network analysis revealed that six discrete memory phases actually exist, three of which have been conflated in the past. At each time point, two distinct memory components separately recruit either V2 or M6 output pathways. Memory retrieval thus features a dramatic convergence from KCs to MB Efferent Neurons.
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two pairs of mushroom body Efferent Neurons are required for appetitive long term memory retrieval in drosophila
Cell Reports, 2013Co-Authors: Pierreyves Placais, Hiromu Tanimoto, Severine Trannoy, Anja B Friedrich, Thomas PreatAbstract:One of the challenges facing memory research is to combine network- and cellular-level descriptions of memory encoding. In this context, Drosophila offers the opportunity to decipher, down to single-cell resolution, memory-relevant circuits in connection with the mushroom bodies (MBs), prominent structures for olfactory learning and memory. Although the MB-afferent circuits involved in appetitive learning were recently described, the circuits underlying appetitive memory retrieval remain unknown. We identified two pairs of cholinergic Neurons Efferent from the MB α vertical lobes, named MB-V3, that are necessary for the retrieval of appetitive long-term memory (LTM). Furthermore, LTM retrieval was correlated to an enhanced response to the rewarded odor in these Neurons. Strikingly, though, silencing the MB-V3 Neurons did not affect short-term memory (STM) retrieval. This finding supports a scheme of parallel appetitive STM and LTM processing.
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mushroom body Efferent Neurons responsible for aversive olfactory memory retrieval in drosophila
Nature Neuroscience, 2011Co-Authors: Julien Sejourne, Yoshinori Aso, Igor Siwanowicz, Pierreyves Placais, Severine Trannoy, Vladimiros Thoma, Stevanus Rio Tedjakumala, Gerald M Rubin, P Tchenio, Kei ItoAbstract:This study reports an anatomical and functional screen of mushroom body–extrinsic Neurons in Drosophila and finds that MB-V2 cholinergic Efferent Neurons are essential for retrieval of aversive short- and long-term memory, but not for memory formation or consolidation. During memory retrieval, MB-V2 Neurons reinforce the olfactory pathway involved in innate odor avoidance.
