Closed‐loop acoustic stimulation during an afternoon nap to modulate subsequent encoding

Abstract

Sleep is able to contribute not only to memory consolidation, but also to post-sleep learning. The notion exists that either synaptic downscaling or another process during sleep increase post-sleep learning capacity. A correlation between augmentation of the sleep slow oscillation and hippocampal activation at encoding support the contribution of sleep to encoding of declarative memories. In the present study, the effect of closed-loop acoustic stimulation during an afternoon nap on post-sleep encoding of two verbal (word pairs, verbal learning and memory test) and non-verbal (figural pairs) tasks and on electroencephalogram during sleep and learning were investigated in young healthy adults (N = 16). Closed-loop acoustic stimulation enhanced slow oscillatory and spindle activity, but did not affect encoding at the group level. Subgroup analyses and comparisons with similar studies lead us to the tentative conclusion that further parameters such as time of day and subjects' cognitive ability influenced responses to closed-loop acoustic stimulation.

Single closed‐loop acoustic stimulation targeting memory consolidation suppressed hippocampal ripple and thalamo‐cortical spindle activity in mice

“…In this first seminal paper hippocampus‐dependent memory consolidation was enhanced by CLAS as compared to a sham session. Although CLAS during NREM sleep appears on average to modulate endogenous EEG SO and spindle activity in a robust fashion (Koo‐Poeggel et al, 2022; Moreira et al, 2021; Ngo, Martinetz, et al, 2013; Ong et al, 2016), effects on memory consolidation were found to be weak and less conclusive as concluded from a recent meta‐analyses (Wunderlin et al, 2021). Moreover, hippocampal responses to CLAS during hippocampus‐dependent memory‐consolidation remain undisclosed.…”

Possible mechanisms to improve sleep spindles via closed loop stimulation during slow wave sleep: A computational study

“…CLAS is able to modify endogenous slow oscillations, sleep spindles, and hippocampal sharp-wave ripple activity [25][26][27][28][29][30] and has been shown to enhance sleep-associated memory consolidation [25,29,31]. For the response to CLAS brain state and timing (e.g., stimulation phase of the oscillatory rhythm) have proven decisive [28,30,32]. CLAS is often used as a double stimulation with two stimuli given at the same phase of two successive SOs.…”