Stéphane Maison, Ph.D.
Instructor of Otology and Laryngology, Harvard Medical School
Olivocochlear Efferent Function
The inner ear receives an efferent innervation from the olivocochlear (OC) bundle that consists of two subsystems: medial (MOC) and lateral (LOC). The peripheral effects of the LOC system of unmyelinated fibers are unknown and the functional role of MOC fibers remain controversial; OC roles in selective attention, control of noise masking and protection from acoustic overexposure have been proposed.
We have also developed a variety of techniques for cochlear phenotypic analysis in the mouse including surgical techniques to activate MOC fibers directly in the brainstem of the mouse. Our current goal is to genetically dissect the role of different transmitters and receptors utilized by both the MOC and LOC systems by phenotypic analysis of carefully selected mutant mouse lines.
1. Maison SF, Liberman MC. Predicting acoustic vulnerability to acoustic injury using a non-invasive assay of olivocochlear reflex strength. J Neurosci 2000;20:4701-7.
2. Maison SF, Luebke AE, Liberman MC, Zuo J. Efferent protection from acoustic injury is mediated via a9 nAChR receptors on outer hair cells. J Neurosci 2002;22:10838-10846.
3. Maison SF, Emeson RB, Adams JC, Luebke AE, Liberman MC. Loss of aCGRP reduces sound-evoked activity in the cochlear nerve. J Neurophysiol 2003;90:2941-2949.
4. Maison SF, Rosahl TW, Homanics GE,Liberman MC. Functional role of the cochlea’s GABAergic innervation: phenotypic analysis of mice lacking GABA(A) receptor subunits a1, a2, a5, a6, b2, b3 or d. J Neurosci 2006;26:10315-10326.
5. Maison SF, Vetter DE, Liberman MC. A novel effect of cochlear efferents: in vivo response enhancementdoes not require a9 cholinergic receptors. J Neurophysiol 2007;97:3269-3278.
6. Maison SF, Casanova E, Holstein GR, Bettler B, Liberman MC. Lack of GABAB receptors in cochlear neurons suggests modulation of outer hair cell function by type-II afferent fibers. JARO 2009;10:50-63.
7. Maison SF, Liu XP, Vetter DE, Eatock RA, Nathanson NM, Wess J, Liberman MC. Muscarinic signaling in the cochlea: pre- and post-synaptic effects on efferent feedback and afferent excitability. J Neurosci 2010;30:6751-6762.
8. Maison SF, Le M, Larsen E, Lee SK, Rosowski JJ, Thomas SA, Liberman MC. Mice lacking adrenergic signaling have normal cochlear responses and normal resistance to acoustic injury but enhanced susceptibility to middle ear infection. JARO 2010;11:449-461.