https://elifesciences.org/articles/55378
Alex’s paper investigates how the relative loudness of sounds is encoded in the biophysical and anatomical properties of the spiral ganglion neurons that innervates the sensory hair cells of the inner ear. The results challenge the prevailing view that intensity sensitivity (leading to loudness perception) is defined solely by the physiology of the pre-synaptic hair cell. Through a combination of patch-clamp electrophysiology and single-cell anatomical labeling, Alex’s study reveals that the biophysical properties intrinsic to auditory neurons vary in a striking spatial gradient that correlates with synaptic position, and ultimately loudness sensitivity. This is the first study to demonstrate such an alignment between the intrinsic biophysics of auditory neurons and their anatomical distribution, and thus represents a major advance in how the field views functional diversity in the auditory nerve.