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. 2021 Jul 12;10:e66396. doi: 10.7554/eLife.66396

Figure 5. Light-evoked EPSCs produced by descending inferior colliculus inputs were due to inwardly rectifying AMPARs.

(A) Sagittal micrograph of a ChAT-Cre/tdTomato brain section showing an IC injection site positive for ChR2-Venus. (B) Sagittal micrograph of the superior olivary complex from the same mouse as in (A). The majority of ChR2-positive fibers were visible in the ventral portion of the VNTB/RPO, near MOC neuron somata. (C) Loose-patch cell-attached recording of a ChR2-positive neuron in the IC. ChR2-Venus-positive neurons can reliably fire action potentials in response to light stimuli. (D) An example of EPSCs evoked during voltage clamp, with holding potentials ranging from −62.8 mV to +57.2 mV in 20 mV steps. (E) I-V relation reporting normalized cumulative data (N = 4–7 per mean, N = 2 at +57.2 mV). Error bars are ± SEM. Abbreviations: SCs, sensory superior colliculus; SCm, motor superior colliculus; IC, inferior colliculus; PAG, periaqueductal gray; labeled II-IV, cerebellar lobules; PG, pontine gray; RPO, rostral periolivary region; DPO, dorsal periolivary region; mcp, middle cerebellar peduncle; LSO, lateral superior olive; VNTB, ventral nucleus of the trapezoid body; 7N, facial motor nucleus; MOC, medial olivocochlear.

Figure 5.

Figure 5—figure supplement 1. IC projections to MOC neurons.

Figure 5—figure supplement 1.

(A) Coronal micrograph of biocytin-filled medial olivocochlear (MOC) neuron in ventral nucleus of the trapezoid body (VNTB) ipsilateral to ChR2-Venus-infected inferior colliculus (IC). (B) High-magnification micrograph of MOC neuron from (A). (C) High-magnification sagittal micrograph of a putative MOC neuron from Figure 5B. While a majority of ChR2-Venus-positive fibers were ventral to MOC neurons, many positive fibers were in close apposition to MOC neuron dendrites and somata.