Abstract
Daily living involves copious information processing that has the potential to “overload” the brain and result in memory loss (i.e., interference). Since we do not need to stabilize each waking experience with a nap before encountering the next, there must be a mechanism that allows the brain to rescue memories damaged by interference. Using a texture discrimination task with short training (120 trials/condition), we induced interference by testing back-to-back conditions in the same visual field before a consolidation period. Four consolidation groups were tested: active wake, quiet wake, non-rapid eye movement (NREM) naps, or NREM+REM naps. Wake produced perceptual learning (PL) in the no interference condition, likely due to the short training, and sleep was not correlated with performance. With interference, PL was abolished in all groups except REM naps. Sleep explained 22% of the variance in magnitude of PL, and minutes of slow wave sleep (SWS, p=.04) and REM (p=.009) were significant predictors of improvement. Performance was correlated with specific sleep features: a) the degree of temporal coupling between spindles and slow oscillations (0.5-1Hz) during Stage 2 (r=.30); b) SWS spindle density (#spindles/SWSmin) from the occipital site contralateral to the trained visual field (r=.54), but not spindle density from the ipsilateral site (r=.09); and c) REM density (#rapid eye movements/REMmin; r=.38). These results, for the first time, demonstrate a process by which the brain can rescue and consolidate memories damaged by interference, and that this process is mediated by specific brain states. Specifically, active wake is sufficient to support PL under conditions of no interference and short training, and REM sleep is critical for rescuing PL damaged by interference. When sleep is necessary for PL, retinotopically-specific sleep spindles, spindle-slow oscillation coupling, and REM density may play important roles.
Meeting abstract presented at VSS 2015