Fig. 11.

Selective stimulation of medial nucleus of the trapezoid body (MNTB) neurons elicit GABAergic Ca²⁺ responses in the lateral superior olive (LSO). (A) Overview of the superior olivary complex in a slice (P3 rat) in brightfield illumination to illustrate experimental approach. A thin optical fibre is used to deliver UV light focally to the MNTB. (B) Responses in the LSO are elicited only from neurons within the boundaries of the MNTB. Top row: area of UV-illumination (presumed site of glutamate release). Bottom row: corresponding responses in an LSO neuron (ΔF with 380 nm excitation). (C) Pure MNTB-evoked Ca²⁺ responses in three neurons. Responses of the upper neurons are partly or completely blocked by bicuculline. Responses in the bottom neuron are unaffected by bicuculline. Ca²⁺ responses are expressed as fluorescence changes with 380 nm excitation. Glutamate was uncaged in the centre of the MNTB (150 μM p-hydroxyphenacyl-glutamate; 50 ms flash duration indicated by the arrowhead). Slice was prepared from a P3 rat.