Effects Of Perceptual Training On Plasticity Of Auditory Cortex And Hippocampus

In the short time window of postnatal development,the structure and function of the rat auditory cortex are extremely sensitive to sound stimulation,showing strong critical period plasticity.With critical periods closed,passive acoustic stimuli hardly induce significant cortical plasticity.Although previous studies have reported various methods(including perceptual training)for modulating the plasticity in the adult auditory cortex,the neural mechanisms by which perceptual training induces cortical plasticity are not well understood.In addition,based on the fact that the perceptual training paradigm we designed contains learning and memory components,it is not clear whether the perceptual training might induce plasticity in the hippocampus.This thesis therefore studied the training-induced plasticity in auditory cortex and hippocampus of adult brain using the rat as a research model.The results showed that1)after training,the average performance score for trained-rats to discriminate the pulse repetition rats of noise pulse trains was maintained above 80%.There was no significant effect of carrier frequencies of pulse trains on discrimination abilities.These results indicate that rats mastered the repetition rate discrimination task for both noise and pure tone trains after training.2)training significantly increased the neuronal repetition-rate following capacity and response synchronization in the primary auditory cortex.These changes in cortical temporal processing were attributed to the enhanced synaptic plasticity as a result of training.3)training enhanced learning and memory function of rats as indicated by performance in the new object recognition test,T-maze test and Ymaze test.These behavioral changes were accompanied by increased long-term potentiation of field potentials and increased expressions of NR2B?Glu R1 and pCa MKII-? in the hippocampus of trained rats.These findings in a rodent model provide evidences for understanding of the synaptic and molecular mechanisms underlying the training-induced plasticity in auditory cortex and hippocampus of adult brain.