Electronic Thesis and Dissertation Repository


Master of Science




Leung, Stan


This study investigated whether an electrographic seizure, or an afterdischarge (AD), inhibits long-term potentiation (LTP) in the hippocampus. Neuromodulation by acetylcholine (ACh) and genetic modification by loss of the ATRX gene on LTP was also examined through the use of VAchT knockout mice and ATRX knockout mice, respectively. Evoked potentials were recorded in the hippocampal CA1 region in freely behaving mice and urethane-anesthetized mice. Basal dendritic LTP was suppressed when elicited 1 h after an AD in all behaving mice, regardless of mouse genotype; LTP was unaffected when induced 1 day or 1 week following an AD. At 1 h post-AD, LTP suppression was largest at(TBS). In the urethane-anesthetized mice, no significant LTP was elicited at 1 h after an AD of 4.5 – 15 s duration, compared to when no AD was evoked irrespective of mouse genotype. In addition, postictal response and LTP magnitude were both negatively correlated with AD duration. Thus, this study has demonstrated that LTP can be suppressed by an AD that was induced one hour earlier, with AD duration being an important factor that contributes to this suppression effect.