Testing the Central Gain Model: Loudness Growth Correlates with Central Auditory Gain Enhancement in a Rodent Model of Hyperacusis.

Summary

The central gain model predicts that loss of auditory input causes maladaptive gain increases that over-amplify sound-evoked activity and produce excessive loudness. Critically testing it requires linking neural changes to perceived loudness in the same subject. The authors combined an operant reaction-time measure of loudness growth with chronic recordings from auditory cortex and inferior colliculus in awake animals, using salicylate to induce temporary hearing loss and hyperacusis. Salicylate produced parallel changes in loudness growth and evoked response-intensity functions, and these changes correlated within individual animals.

Key findings

• Combined behavioural loudness-growth measures with chronic cortex and inferior-colliculus recordings in the same awake animals.
• Salicylate produced parallel shifts in loudness growth and evoked response-intensity functions.
• Loudness and sound-evoked activity changes correlated within individual animals, the critical prediction of the model.
• Provides strong experimental support for the central gain model of hyperacusis.