Figure 5. Medial nucleus of the trapezoid body-lateral superior olive (MNTB-LSO) input maps are enlarged upon disruption of TMEM16A.

(A) Exemplary MNTB input maps from wildtype (P9) and cKO mice (P10) as revealed by whole-cell current-clamp recordings (dotted line outlines the MNTB area, grid points indicate glutamate uncaging sites). The location of responsive (colored squares) and unresponsive (open squares) uncaging sites is indicated. Scale bar 40 µm. (B) Uncaging of glutamate close to presynaptic MNTB neurons gives rise to synaptic responses of various peak amplitudes (left), elicits action potentials (middle), or fails to evoke significant voltage signals (right) in the recorded LSO neurons (see color code below). (C, D) Quantification of MNTB input areas (summed area of all responsive uncaging sites) on a recorded LSO neuron and of the MNTB input widths (maximal distance of stimulations sites that evoked depolarization greater than 10 mV along the mediolateral [tonotopic] axis of the MNTB). MNTB input areas were normalized to the corresponding MNTB cross-sectional area and MNTB input widths to the length of the mediolateral axis of the MNTB. Values represent mean ± SEM (n = 10 WT; n = 10 cKO [P9–11]; two-way unpaired Student’s t-test: MNTB input area: p=0.0017, MNTB input width: p=0.0073).

Figure 5—figure supplement 1. Spatial resolution of glutamate uncaging and additional examples of medial nucleus of the trapezoid body (MNTB) input maps recorded from wildtype and cKO mice.

(A) Schematic representation of the MNTB from a wildtype mouse recorded at P8 (dotted line represents the MNTB area, grid points show glutamate uncaging sites, black cross indicates the location of the recorded MNTB neuron). Spatial resolution of glutamate uncaging was assessed by whole-cell current-clamp recordings. Stimulation sites that evoked action potentials (red squares) were limited to the close proximity of the recorded MNTB neuron. Stimulation sites that were located in greater distance to the recorded MNTB neuron evoked subthreshold responses (orange squares) or no response (white squares). Scale bar 20 µm. (B) Uncaging of glutamate close to the recording site strongly depolarizes or elicits action potentials in the recorded MNTB neuron (see color code). (C) Quantification of the maximal action potential eliciting distance from the uncaging site to the center of the recorded MNTB neuron. Values represent mean ± SEM (n = 6 [P8–11]). (D, E) Schematic representations of the MNTB showing reconstructed maps of MNTB inputs, based on the current-clamp recordings in the lateral superior olive (LSO) (LSO not shown) from wildtype (D, left P11; D, right) and cKO mice (E, left P10; E, right P11). Scale bar 40 µm.