Central Gain Restores Auditory Processing following Near-Complete Cochlear Denervation.

Summary

Lesioning >95% of cochlear-nerve afferents in mice (sparing hair cells) nearly abolished the auditory brainstem response, yet tone-detection behavior stayed near-normal. As auditory-nerve signals weakened, sound-evoked cortical activity rebounded to or above normal, a progressive, compensatory 'central gain' that restored rate-coded sound features but not fine spike timing. Central plasticity, not the periphery, drives the perceptual consequences of cochlear damage.

Key findings

• Central gain compensates for massive loss of cochlear-nerve input, restoring rudimentary sound detection.
• Cortical activity rebounds above normal as peripheral input falls, a compensatory but potentially maladaptive gain increase.
• Recovers rate-coded features but not spike-timing-dependent ones (e.g., speech/modulation).