Tonotopy disruption of a central auditory nucleus in a mouse model with enhanced MOC activity

DI GUILMI, MN, GÓMEZ-CASATI, ME, BOERO, LE, WEDEMEYER C, RODRÍGUEZ-CONTRERAS A AND ELGOYHEN AB

Valparaiso

Simposio; IHeaR Meeting; 2018

The auditory system in many mammals is immature at birth but precisely organized inadults. Spontaneous activity in the inner ear comes into play to guide this process. Thisspontaneous activity is modulated by an efferent pathway that descends from the brain(Walsh et al., 1998). In the medial nucleus of the trapezoid body (MNTB), neurons aretopographically organized along a medio-lateral axis with the most medially locatedcells responding to high frequencies, changing to lower characteristic frequencies in themost lateral cells. The specific aim of this work is to understand the role of the medialolivocochlear (MOC) system in the correct establishment of the MNTB tonotopy.We used mice with enhanced MOC activity (Chrna9L9?T, knock-in, KI) in which theα9 nicotinic receptor subunit bears a point mutation that leads to a gain of function(Taranda et al., 2009). Auditory brainstem responses (ABR) at P21 andelectrophysiological recordings between P12-14 (patch-clamp, whole-cellconfiguration) on brainstem slices containing the MNTB were evaluated. Both currentand voltage-clamp configurations were performed in order to study the tonotopy of theMNTB.