Neuronal heterogeneity and stereotyped connectivity in the auditory afferent system. Neuronal heterogeneity and stereotyped connectivity in the auditory afferent system

Spiral ganglion (SG) neurons of the cochlea convey all auditory inputs to the brain, yet the cellular and molecular complexity necessary to decode the various acoustic features in the SG has remained unresolved. Using unbiased single-cell RNA sequencing, we identified four types of SG neurons, including three novel subclasses of type I neurons and the type II neurons, and provide a comprehensive genetic framework that define their potential synaptic communication patterns. The connectivity patterns of the three subclasses of type I neurons with inner hair cells and their electrophysiological profiles suggest that they represent the intensity-coding properties of auditory afferents. Moreover, neuron type specification is already established at birth, indicating a neuronal diversification process independent of neuronal activity. Thus, this work provides a transcriptional catalog of neuron types in the cochlea, which serves as a valuable resource for dissecting cell-type-specific functions of dedicated afferents in auditory perception and in hearing disorders. Overall design: Exploring heterogeneity of spiral ganglion neurons in both P3 and adult mice Please note that the single cells were sorted into 384-well plates, and cells from each well were barcoded afterwards using Nextera index adapters during library preparation. Therefore the number of the well (A1-P24) represents each cell (A1-P24).