
==== Front
bioRxiv
BIORXIV
bioRxiv
2692-8205
Cold Spring Harbor Laboratory

10.1101/2024.09.13.612867
preprint
1
Article
Population coding of auditory space in the dorsal inferior colliculus persists with altered binaural cues
Rogalla Meike M.
Quass Gunnar L.
Yardley Harry
Martinez-Voigt Clara
Ford Alexander N.
Wallace Gunseli
Dileepkumar Deepak
Corfas Gabriel
Apostolides Pierre F.
13 9 2024
2024.09.13.612867https://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which allows reusers to copy and distribute the material in any medium or format in unadapted form only, for noncommercial purposes only, and only so long as attribution is given to the creator.
http://biorxiv.org/lookup/doi/10.1101/2024.09.13.612867
nihpp-2024.09.13.612867.pdf
Abstract

Sound localization is critical for real-world hearing, such as segregating overlapping sound streams. For optimal flexibility, central representations of auditory space must adapt to peripheral changes in binaural cue availability, such as following asymmetric hearing loss in adulthood. However, whether the mature auditory system can reliably encode spatial auditory representations upon abrupt changes in binaural input is unclear. Here we use 2-photon Ca 2+ imaging in awake head-fixed mice to determine how the higher-order "shell" layers of the inferior colliculus (IC) encode sound source location in the frontal azimuth, under binaural conditions and after acute monaural hearing loss induced by an ear plug ipsilateral to the imaged hemisphere. Spatial receptive fields were typically broad and not exclusively contralateral: Neurons responded reliably to multiple positions in the contra- and ipsi-lateral hemifields, with preferred positions tiling the entire frontal azimuth. Ear plugging broadened receptive fields and reduced spatial selectivity in a subset of neurons, in agreement with an inhibitory influence of ipsilateral sounds. However ear plugging also enhanced spatial tuning and/or unmasked receptive fields in other neurons, shifting the distribution of preferred angles ipsilaterally with minimal impact on the neuronal population’s overall spatial resolution; these effects occurred within 2 hours of ear plugging. Consequently, linear classifiers trained on fluorescence data from control and ear-plugged conditions had similar classification accuracy when tested on held out data from within, but not across hearing conditions. Spatially informative neuronal population codes therefore arise rapidly following monaural hearing loss, in absence of overt experience.
==== Body
pmc
