Effects of Auditory Training on Parvalbumin-Expressing Interneurons in Brain Regions Associated with Task Demands.

Perceptual training is characterized by strong task and stimulus specificities, leading prior studies on auditory training-induced effects to focus predominantly on the auditory system, particularly the auditory cortex. However, it remains unclear whether such training-induced effects extend beyond the auditory cortex to other brain regions involved in task-related processing. In this study, we trained adult rats on an auditory cue-based discrimination task and then examined post-training changes in the densities of parvalbumin-expressing (PV+) interneurons, a key marker of GABAergic inhibition, across the inferior colliculus (IC), hippocampus, medial prefrontal cortex (mPFC), and basolateral amygdala (BLA)-all of which are implicated in task demands. We found that training significantly increased the PV+ interneuron density in the dentate gyrus of the hippocampus but decreased it in the basal nucleus of the BLA; however, no significant changes were detected in the IC or mPFC. The findings revealed region-specific effects of auditory training on inhibitory circuits mediated by PV+ interneurons, demonstrating that training-induced effects extend beyond the auditory cortex to other brain regions linked to task-related processing. This highlights the potential of auditory training as a strategy for remodeling integrated sensory and cognitive functions in older children and adults.