Single closed-loop acoustic stimulation during NREM sleep in mice

Abstract

Sleep rhythms can elucidate the neurophysiological processes underlying sleep-dependent memory consolidation, and their neuromodulation. Enhanced slow oscillation (SO) activity, as well as increased phase-coupled spindle and hippocampal sharp wave-ripple (SWR) activity, are associated with improved memory consolidation during sleep across mammalian species. In humans, closed-loop acoustic stimulation (CLAS) has been shown to facilitate the grouping of sleep spindles to SOs using EEG scalp electrodes. In the present study, single closed-loop acoustic stimulation (sCLAS) was implemented in mice, in order to investigate the modulation of SOs, sleep spindles as well as SWRs. Memory retention performance of mice measured in an object place recognition (OPR) task did not differ significantly from the control session under sCLAS, although differential responses were found for Up- versus Down-State Stimulation. Application of sCLAS in the 3h sleep interval did not affect the measured sleep parameters significantly. In all conditions, the acoustic stimuli produced an acute increase in SWR activity followed by a significant suppression of at least 1 second. The only electrophysiological outcome indicating a possible relationship to mnemonic function was the SO-SWR coupling. Further experiments are necessary to investigate the translational relevance of (s)CLAS in mice.