Effects Of Auditory Training On Expression Of Auditory And Cognition-related Protein(Parvalbumin)

Perceptual training induced-plasticity in the mature brain has been reported in many previous studies.In the auditory system,it has been shown that auditory training significantly modifies processing selectivity in multi-parametrical domains and representational topographies in the adult auditory cortex.It has been proposed that training-based cortical plasticity is restricted only to stimulus parameters that are relevant to behavioral demands.As behavioral tasks applied here in this study have significant learning and memory components(they require animals to identify a remembered target stimulus from a set of distracter stimuli),it is conceivable that auditory training might also induce plastic changes in the hippocampus and prefrontal cortex,two brain structures believed to contribute to learning and memory and cognitive functions.As a sub-group of GABAergic inhibitory interneurons,Parvalbumin positive(PV+)neurons play an important role in sensory information processing,training-based brain plasticity,and learning and memory function.In this study,we examined if our memory-based auditory training applied in young adulthood detectably impacted the status of this key neuronal population in the primary auditory cortex(Al),hippocampus(HP),and medial prefrontal cortex(mPFC)of rats,by using the immunohistochemical method.We found that auditory training significantly reduced the number of PV+neurons in each layer of the cortical field A1.The number of PV+ neurons in the subfield CA3 of hippocampus also reduced but that in the subfield DG increased as a result of training.No measurable changes in PV expression,however,were observed in both prelimbic cortex area(PL)and infralimbic area(IL)of the medial prefrontal cortex.These results in the rodent model demonstrate that auditory training differently affects PV expression in the cortical field Al and hippocampus.They shall help to understand neural mechanisms underlying training-based plasticity in both sensory and learning and memory systems in the mature brain.