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Synaptic Inhibition of Medial Olivocochlear Efferent Neurons by Neurons of the Medial Nucleus of the Trapezoid Body
- Source :
- The Journal of Neuroscience
- Publication Year :
- 2019
- Publisher :
- Society for Neuroscience, 2019.
-
Abstract
- 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 STATEMENTMedial 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.
- Subjects :
- Cochlear Nucleus
Male
0301 basic medicine
Patch-Clamp Techniques
OHC
Efferent
Olivary Nucleus
Biology
Inhibitory postsynaptic potential
Cochlear nucleus
inhibitory synapse
Mice
03 medical and health sciences
Neurons, Efferent
0302 clinical medicine
Glutamates
otorhinolaryngologic diseases
medicine
Animals
Trapezoid body
Auditory system
auditory
Axon
medial olivocochlear
Cochlear Nerve
Research Articles
Trapezoid Body
General Neuroscience
Excitatory Postsynaptic Potentials
MNTB
Axons
Electric Stimulation
Mice, Inbred C57BL
030104 developmental biology
medicine.anatomical_structure
Acoustic Stimulation
nervous system
efferent
Synapses
Female
sense organs
Neuron
Brainstem
Neuroscience
030217 neurology & neurosurgery
Cellular/Molecular
Brain Stem
Subjects
Details
- ISSN :
- 15292401 and 02706474
- Volume :
- 40
- Database :
- OpenAIRE
- Journal :
- The Journal of Neuroscience
- Accession number :
- edsair.doi.dedup.....1942cac3f36cb60d7b3407f0e177b917