Mechanism Of Perceptual Training-induced Tone-Sequence Sensitivity In Adult Rat

Perceptual training has an important role in the development and plasticity in the auditory cortex, while the importance of behavioral relevance and attention in generating adult plasticity is a major research field for sensory system. The present study used rats as animal model to find out the underlying mechanism of how perceptual training influenced the tone-sequence sensitivity of neurons in the primary auditory cortex, through behavior and molecular biological methods.This dissertation includes two parts as follow:1. Perceptual training enhances the tone-sequence sensitivity and alters expression of NMDA subunits and GABAA subunits in adult ratIn this part, we used7EXP rats,8Sham control rats and8Naive rats for the study. Tone-sequence discrimination test results have shown that rats were learning to identify the target pair from the nontarget pairs. Further more, western blotting was used to examine the changes of the inhibitory and excitatory receptor. Then results showed that the tone-sequence discrimination training resulted in increasing the expression of the NMDA receptor subunits, NR2A and NR2B; GABAA receptor subunits, α1,β2of the auditory cortex. In addition, the ratio between NR2A and NR2B and the variation rate of all inhibitory receptor expressions and the excitatory receptor expressions were also increased. Our findings suggest that tone-sequence discrimination training can significantly increase the expression of the inhibitory and excitatory receptor.2. Maintenance of perceptual training enhancing the tone-sequence sensitivityIn this part, we used EXP recovery rats (which return to normal condition for two months) as model, investigated the maintenance of tone-sequence discrimination training induced changes of auditory system by behavior and molecular biological methods. We found that, compared with the age-matched Sham control and Naive, the EXP rats still had better performance. Tone-sequence discrimination test results have shown that rats identified the target pair much faster. In addition, we also detected significantly increases in NMDA receptor NR2A, NR2B subunits; GABAA receptor αl, β2subunits protein expression. Meanwhile, the ratio of NR2A/NR2B, the variation rate of all inhibitory receptor expressions and the excitatory receptor expressions were also increased. These observations indicate the persistent higher expression levels of the GABAergic and glutamatergic receptors expression induced by tone-sequence discrimination training, might be responsible for the maintenance of improved effects in auditory tone-sequence sensitivity.