Abstract:
Long-term Potentiation (LTP) is the best characterized forms of enhancement in synaptic plasticity which is a widely accepted model of learning and memory. The modification of long-term plasticity is a complex process and varies throughout synaptic events. The present research, in vitro brain slice techniques were used to study the efficacy of tetanic stimulation and theta-burst stimulation (TBS) for LTP induction in rats. In addition, the study also investigated the effects of cortical spreading depression (CSD), picrotoxin-an antagonist of gamma aminobutyric acid A (GABAA) receptor on the tetanic-induced LTP. For results of efficacy of stimulate patterns, the stimulation intensity was 0.37+0.0677V with tetanic stimulation and 0.31+0.0862V with TBS. There were no significant differences among groups (one-way ANOVA, P=0.122). TBS effectively induces LTP more than tetanic stimulation with 144.42±6.54% of baseline (N=10) and 134.88±6.92% of baseline (N=10), respectively. In addition, the picrotoxin effectively induced LTP with 140.25±4.18% of the baseline in the picrotoxin group (N=8) versus 134.88±6.92% of the baseline in the control group (N=10). In group with picrotoxin applied to CSD, we obtained the smallest magnitude of LTP (120.15±3.73% of the baseline, N=8). The experimental data were interpreted by least squares curve fitting which modeled as three mathematical equations, polynomial, exponential and power equations. I found that the model of power equation produced the best in adjusted value and initial post-tetanic potentiation approximation. For LTP approximation, there were similar quantification that the polynomial model produced a small relative error with abundant residual while there were not many residual from the exponential model and power model. Therefore, the power equation was a suitable model for LTP approximation or description of synaptic response. More over the nonlinear attribute of LTP had an influence on the fitting, with respect to increasing the accuracy of the parameters and the compatibility of combination of stimuli that produce LTP.
