Abstracts

Rationale: Epilepsy is a common and devastating medical problem, which remains insufficiently treated in 30% of patients. Mesial Temporal Lobe Epilepsy (MTLE) is the most prevalent form of medically intractable epilepsy and many of MTLE patients present with memory deficits. This study evaluates how abnormal activity (seizures and inter-ictal activity) originating from the temporal lobe affects short-term memory in a non-human primate (NHP) model of MTLE. Methods: The NHPs were trained to perform a novel object recognition task and their memory tested before the induction of seizures (baseline) and at several time points following seizure induction. Recognition was measured by the time the animal spent looking at a novel image compared to one that had already been presented. This was performed using an eye tracker and frame-by-frame analysis of eye movements (Tobii Pro X3-120, Tobii Studio Lab). Seizures were induced by local hippocampal injection of a GABAa antagonist (Penicillin (PCNg)) via a cannula. Seizure sessions were repeated at least one week apart with NHP1 and NHP2 receiving, respectively, 16 and 14 injections. Results: Following the induction of seizures, both animals were still spending more time looking at novel pictures compared to old ones, but the time spent on the novel pictures was significantly decreased compared to baseline testing. In addition, for both animals the time spent on the novel pictures was negatively correlated with the cumulative dose of penicillin. Conclusions: These results suggest that, while subtle, there is an effect of MTLE seizures on recognition memory. The hippocampus plays a critical role in many types of memory, and effect of seizures and treatment on recognition and spatial memory is currently under evaluation. Funding: NIH, NINDS, Brain initiative (5UG3NS100559-02)