Does Sleep Play a Role in the Consolidation of Novelty- or Curiosity-Driven Memory Enhancement?

Abstract

The persistence of memory over time is dependent on a variety of events between learning and remembering, one of which is sleep. Additionally, the strength of initial learning influences how well things will be remembered later on, and the way the sleeping brain processes information has been found to rely on some of these encoding factors. Given the extensive literature on the influence of dopamine on learning, we wanted to examine how two memory benefits thought to rely on dopamine – the novelty effect and the curiosity effect – may be impacted by periods of sleep or wakefulness. Three experiments were conducted: one in which novel scenes were viewed and associated information was recalled after wakefulness or sleep, one where subjects learned in the lab or at home, and one in which participants rated their curiosity for learning materials and were tested later after sleep or wakefulness (and in which eye blink rate (EBR) and PSG measures were observed). Our findings failed to replicate the novelty effect in the first two experiments, making our prediction regarding sleep difficult to assess. Though we replicated the curiosity effect in the third study, our predictions about sleep and slow wave sleep were not supported. However, N2 and REM were unexpectedly observed to play a role in this effect, a finding that deserves more assessment. Finally, EBR, an indirect measure of dopamine, was negatively associated with the curiosity effect due to a positive relationship with the retention of low curiosity stimuli. Future research should investigate this sensitive novelty effect in humans further and continue to examine EBR as a predictor of learning.