Sleep Dependent Memory Consolidation in People With Epilepsy (5469)

Objective: We hypothesized that sleep would not benefit memory retention in people with epilepsy. Background: People with epilepsy commonly report long-term memory difficulties. However, the underlying mechanisms of these deficits are unknown. The hierarchical nesting of slow oscillations, spindles, and ripples during slow wave sleep (SWS) has been proposed to provide the temporal framework for consolidation of long-term memory by shuttling the newly formed memories from the hippocampus to the neocortex. All of these classes of neural oscillations are also impacted by epilepsy. We hypothesized that sleep would not benefit memory retention in people with epilepsy. Design/Methods: To test it, we compared the epilepsy patients’ (n=5) performance on a sleep-sensitive verbal memory task over two conditions, sleep and wakeful retention intervals. The study had two phases – learning and retrieval. We used a Paired-Associated Learning (PAL) task, which assesses verbal declarative learning (left hippocampus) and proven to be sensitive to effects of sleep. Subjects were tested immediately after the learning phase (criterion trial) and also after a two-hour “nap” retention interval on the sleep day, and a two-hour period of wakefulness on a control day. Results: “Retention Performance” was defined by the percentage of recalled word pairs during the retrieval test, with performance on the criterion trial was set to 100%. All of the participants had some periods of SWS during the “nap” retention interval; however, the “Retention Performance” was not significantly different between the sleep and wakeful conditions (p-value>0.05). Conclusions: We demonstrated that unlike what reported in people without epilepsy, SWS did not benefit memory retention in people with epilepsy. We proposed that sleep-dependent memory consolidation is impaired in epilepsy patients and may underlie their long-term memory deficits. We hope that through the interventions during deep sleep, we will be able to enhance memory consolidation and improve long-term memory in people with epilepsy. Disclosure: Dr. Khadjevand has nothing to disclose. Dr. Pal Attia has nothing to disclose. Dr. Miller has nothing to disclose. Dr. St. Louis has nothing to disclose. Dr. Worrell has nothing to disclose.