Effects Of Auditory Training On Expression Of Plasticity-related Protein (Parvalbumin) In Rat Brain

Perceptual training has strong task and stimulus specificities,therefore earlier studies on auditory training-induced plasticity mainly focused on the auditory system(particularly the auditory cortex).However,the auditory system has direct or indirect fiber links with other systems or structures of the brain to complete the functional integration.In addition,the auditory training paradigm here we designed contains significant components of learning and memory,decision making,and reward,as well as the auditory perception.It is thus conceivable that training-induced plasticity might also occur in those brain regions that are linked to these advanced brain functions.To test this hypothesis,we first trained a group of adult rats for ~4 weeks in a sound repetition rate discrimination task.We then examined the post-training changes in densities of parvalbumin positive(PV+)neurons in the primary auditory cortex(A1),inferior colliculus(IC),hippocampus(HIP),medial prefrontal cortex(mPFC),and the basolateral nuclear complex of the amygdala(ABL),brain structures that are believed to contribute to the auditory perception,learning and memory,decision making,and reward etc..We found that auditory training significantly reduced the density of PV+ neurons in each layer of the cortical field A1,especially the layers V and VI.The density of PV+ neurons in the subfield BLa of ABL was also reduced but that in the subfield DG of HIP increased as a result of training.No measurable changes in the densities of PV+ neurons,however,were observed in the subfields Lvm and BLp of ABL,the mPFC,and the IC.These results show that auditory training differently affects the PV expression in brain regions of A1,HIP and ABL.Thus effects of auditory training on adult brain are closely associated with the training paradigm designed.Our findings help to understand neural mechanisms underlying training-based plasticity in the mature brain.They also provide a theoretical basis for improving brain functions through perceptual training.