The role of sleep in forgetting in temporal lobe epilepsy: a pilot study

The purpose of this study was to examine how sleep impacts memory function in temporal lobe epilepsy (TLE). Patients with TLE (n=7) and control subjects (n=9) underwent training and overnight testing on (1) a motor sequence task known to undergo sleep-dependent enhancement in healthy subjects, and (2) the selective reminding test, a verbal memory task on which patients with TLE have shown impaired performance 24 hours after training. Sleep data were collected by polysomnography. Results indicate that patients with TLE display greater forgetting on the selective reminding test compared with controls over 12 hours of daytime wakefulness, but not over a similar period including a night of sleep. Slow wave sleep is correlated with overnight performance change on the selective reminding test. Patients with TLE show no deficit in sleep-dependent motor sequence task improvement. The findings provide potential insight into the pattern and pathophysiology of forgetting in TLE.