Different Intensity Of Job Training, The Effect Of Synaptic Transmission In The Hippocampus Acquisition Ltp Development Process

Using the methods of chronically implanting microelectrodes and the combined application of electrophysiology with behavior in vivo, Firstly, we examined the Input/Output (I/O) characters of tetanic-LTP in the hippocampal PP-DG pathway. The tetanic-LTP was used as a marker and the discrimination-learning as a pattern to observe the effects of task-traning of different intensity on the efficacy of synaptic transmission in hippocampal PP-DG pathway during the development of learning-dependent LTP (Ld-LTP). Weather the learning behavior-related priming effect to modify the efficacy of synaptic transmission exists during the development of Ld-LTP was sequentially investigated in this experiment The results showed as follwings:1. Two types of tetanic-LTP was induced in the hippocampal PP-DG pathway in vivo by 10 bursts (2 sec) or by 3 bursts (600 ms) of theta-rhythm-burst high-frequency stimulation, which were termed "strong -type LTP" and i'weak-type LTP" in this paper. The strong-type LTP with a character of "full or none" approximately was remarkably different to the weak-type LTP with a gradually development phase.2. There was no evident change observed in PSA (Population-Spike Amplitude) in the hippocampal PP-DG pathway during 120min after task training of different intensity (20trials, 40trials and 60trials). Whereas the Ld-LTP was recorded in 40 and 60 trials trained rats after 24 hrs, which suggested that there should be a development phase commonly before the Ld-LTP was expressed and higher intensity training (such as 60 trials) couldnot advance the expression of Ld-LTP.3. The amplitude and the time-dependent development of strong-type LTP induced at the time of 15min after training of different intensity showed no differences compared with the control group (untrained group), which indicates training of different intensity has no significant effects on the strong-type LTP during the development of Ld-LTP.4. The amplitude and the time-dependent development of weak-type LTP induced at the time of 15min after 20trials training showed no differences compared with the control group (untrained group). However, the tendency of LTP development was changed after the time of about 40min in 40 trials trained rats in which the amplitude was enhanced (148%?%, P<0.01) and duration (>48hr) was prolonged. The development characteristic of LTP was changed in 60 trials trained rats, the maximal potentiation of PS appeared right after HFS(255 ?18%, P<0.01), and this high potentiation lasted to 48hr, with the character of strong-type LTP. The results indicated that task training can enhance the weak-type LTP, which implies that the priming effect to modify efficacy of synaptic transmission during the development of L-d LTP exists.