Rapid Emergence of an Adaptive Spatial Representation

Peripheral sensory cue availability fluctuates across timescales ranging from seconds to years. This requires central circuits to continuously adapt their representations while preserving established codes, but how the brain achieves this flexibility is unknown. Using two-photon calcium imaging in the mouse inferior colliculus, we address this knowledge gap by testing how neurons encode sound location before and after abruptly disrupting binaural cues via monaural hearing loss. Despite measurable single neuron changes, altering binaural cues had remarkably little impact on the encoding of auditory space. Rather, neural activity rotated into a spatially informative representational subspace, orthogonal to the original binaural axis, within two hours of hearing loss. This rotation occurred in absence of overt experience or training, and reflected a shift from ON- to OFF-dominated spatial selectivity. Thus, central population codes rapidly reorganize to accommodate sudden changes at the periphery, without overwriting existing representations.