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A review of synaptic mechanisms of vestibular efferent signaling in turtles: Extrapolation to efferent actions in mammals
- Source :
- Journal of Vestibular Research. 23:161-175
- Publication Year :
- 2013
- Publisher :
- IOS Press, 2013.
-
Abstract
- The vestibular labyrinth of nearly every vertebrate class receives a prominent efferent innervation that originates in the brainstem and ends as bouton terminals on vestibular hair cells and afferents in each end organ. Although the functional significance of this centrifugal pathway is not well understood, it is clear that efferent neurons, when electrically stimulated under experimental conditions, profoundly impact vestibular afferent discharge. Effects range from chiefly excitation in fish and mammalian vestibular afferents to a more heterogeneous mixture of inhibition and/or excitation in amphibians, reptiles, and birds. What accounts for these diverse response properties? Recent cellular and pharmacological characterization of efferent synaptic mechanisms in turtle offers some insight. In the turtle posterior crista, vestibular efferent neurons are predominantly cholinergic and the effects of efferent stimulation on vestibular afferent discharge can be ascribed to three distinct signaling pathways: (1) Hyperpolarization of type II hair cells mediated by α9/α10-nAChRs and SK-potassium channels; (2) Depolarization of bouton and calyx afferents via α4β2*-containing nAChRs; and (3) A slow excitation of calyx afferents attributed to muscarinic AChRs. In this review, we discuss the evidence for these pathways in turtle and speculate on their role in mammalian vestibular efferent actions where synaptic mechanisms are largely unknown.
- Subjects :
- Male
Efferent
Presynaptic Terminals
Receptors, Nicotinic
Biology
Hair Cells, Vestibular
Neurons, Efferent
otorhinolaryngologic diseases
Animals
Receptors, Cholinergic
Neurons, Afferent
Vestibular Hair Cell
Mammals
Vestibular system
General Neuroscience
Efferent Neuron
Receptors, Muscarinic
Sensory Systems
Turtles
Crista
Otorhinolaryngology
Cholinergic
Female
Vestibule, Labyrinth
sense organs
Neurology (clinical)
Brainstem
Neuroscience
Type II Hair Cell
Subjects
Details
- ISSN :
- 18786464 and 09574271
- Volume :
- 23
- Database :
- OpenAIRE
- Journal :
- Journal of Vestibular Research
- Accession number :
- edsair.doi.dedup.....2233f93fa50061058b2b4e543a849909