Habituation enhances auditory perceptual capacity in adult rats

We have already demonstrated that pretreatment of adult rats with a 48-h-long “repetitive non-reinforced sound exposure (SE)” improves performance in two-sound discriminative operant conditioning (sound exposure-modulated discrimination [SED]). This three-part study addressed the neural basis of SED by parametrically analyzing SED: effects of the SE using various sound signals were compared during the performance of a sound-discrimination task. Experiment 1 provided evidence that SED was due to the improvement of auditory perceptual capacity rather than due to a change in motivation or attention or interference with association process. Results of Experiment 2 made it likely that SED took place mainly in higher cortical auditory fields, which potentially integrate acoustic information beyond the cochleotopy. Results of Experiment 3 favored the idea that SED was based on a stimulus-specific decrease rather than a stimulus-specific increase in the responsivity of the auditory system. Collectively, it is suggested that auditory habituation plays an important role in SED, i.e., a certain form of auditory perceptual learning.