Single cell RNA sequencing of lateral and medial olivocochlear efferent neurons using PatchSeq

Olivocochlear (OC) efferent neurons are the final component of the descending auditory system. The lateral olivocochlear (LOC) neurons innervate type I spiral ganglion neurons (SGN). Their role in hearing is unknown, but they may have roles in protection from noise trauma or changing the threshold of SGN activation. The medial olivocochlear (MOC) efferent neurons innervate outer hair cells (OHC), inhibiting OHC function and thus dampening cochlear vibrations. LOC and MOC function is poorly understood at the single cell level, but recent use of transgenic mice (ChAT-IRES-Cre; tdTomato) expressing fluorescent reporters in cholinergic neurons, including LOC and MOC neurons, has allowed patch-clamp recordings from the neurons in mouse brainstem slices to begin to characterize their intrinsic electrical properties and synaptic activity. Recent single nucleus sequencing experiments from LOC and MOC neurons has given insight into the genetic programs that generate their function, including changes to expression profiles following noise trauma. Here we utilize the PatchSeq technique to combine patch-clamp electrophysiological recordings with deep single-cell transcriptome analysis from identified LOC and MOC neurons in transgenic ChAT-IRES-Cre; tdTomato mice. In this preliminary dataset, we generated patch-clamp electrophysiology data and single cell transcriptome data from 18 identified LOC and 13 identified MOC neurons. Overall design: Patch-clamp recordings were performed from red fluorescent neurons in the lateral superior olive for lateral olivocochlear (LOC) neurons or ventral nucleus of the trapezoid body for medial olivocochlear (MOC) neurons in brainstem slices from ChAT-IRES-Cre; tdTomato transgenic mice. Following recordings, cellular contents were aspirated, cDNA libraries were generated according to the SmartSEQ2 protocol, and individual cell libraries were prepared using Nextera DNA Library Preparation kits (Illumina) and sequenced on an Illumina MiSeq in 75 bp paired end configuration.