Biology subjects

Moelle, M.

Publications and source records attributed to Moelle, M..

3 recordsLinked to original sources

bioRxiv2026

From co-occurrence to increasingly precise temporal coordination: Development of slow oscillation-spindle coupling from infancy to toddlerhood

The precise temporal coordination of sleep spindles and slow oscillations (SOs) is a key mechanism of memory consolidation during sleep, yet little is known about its emergence early in life. Here, we investigated the development of SO-spindle coupling in 9- to 16-month-old infants and toddlers. While morphologies of spindles and SOs were largely comparable between infants younger than one year and toddlers older than one year, their temporal coordination showed clear age-related changes. In infants, SO-spindle co-occurrence was highest over occipital cortex regions, as was to be expected by chance based on the spatial distribution of the two oscillations. Co-occurrence rates in infants already exceeded chance level, but only at central regions where the highest co-occurrence rates were observed in toddlers. Moreover, a nesting of spindles into the upstate of SOs was evident in fronto-central regions even in infants, and increased in strength and precision with age. Together, these findings suggest that coordinated SO-spindle coupling emerges in the second half of the first year of life and becomes increasingly precise across the transition into toddlerhood.

neuroscience↗

bioRxiv2025

Closed-loop acoustic stimulation modified by cathodal tDCS is beneficial for retention

We investigated how combining transcranial direct current stimulation (tDCS) with closed-loop acoustic stimulation (CLAS) during slow-wave sleep (SWS) affects memory consolidation and sleep-related neural oscillations. Cathodal tDCS was used to slightly reduce cortical excitability, thereby simulating a shifted brain state during CLAS and allowing us to compare the effects of standard CLAS to CLAS delivered under altered cortical conditions (CmodCLAS). Twenty-three participants (mean age 21.3 {+/-} 2.6 years) completed two experimental nights: one with CLAS alone and one with CLAS combined with cathodal tDCS (CmodCLAS). Overnight retention on declarative memory tasks and morning learning performance were assessed. Memory outcomes revealed that CmodCLAS, but not CLAS alone, significantly improved overnight retention on the figural paired-associate task. In the EEG, CmodCLAS shifted the time-locked response to acoustic stimulation toward more negative potential values at the frontal region. CmodCLAS also prolonged slow oscillation (SO) duration at frontal sites while shortening SO duration at occipital sites, an effect not observed during standard CLAS. These findings demonstrate that the baseline level of cortical excitability during sleep modulates both the cognitive and electrophysiological effects of CLAS. They highlight the importance of brain state for non-invasive CLAS during sleep and suggest that CmodCLAS may serve as a useful approach for enhancing prefrontal cortical function during SWS. Significance statementNon-invasive brain stimulation (NIBS) is a promising approach to modulate brain activity and function. Unfortunately, NIBS studies are challenged by heterogenous findings. In addition to protocol differences, variability may depend strongly on the brains baseline activity (or brain state). Here, we used transcranial direct current stimulation (tDCS) to simulate a different brain state while applying closed-loop acoustic stimulation (CLAS) during slow-wave sleep (SWS). Sleep has been shown to enhance overnight memory retention. Results demonstrated significantly improved retention performance for cathodal tDCS modulated CLAS (CmodCLAS) as compared to CLAS alone. Furthermore, electrophysiological responses time-locked to the acoustic stimulus and spontaneous electrophysiological rhythms of SWS suggest that hippocampo-cortical function was specifically enhanced by CmodCLAS. Thus, underscoring the potential therapeutic relevance of CmodCLAS.

neuroscience↗

bioRxiv2022

Single acoustic closed loop stimulation in mice to modulate hippocampo-thalamo-cortical activity and performance

Neural brain rhythms of sleep reflect neuronal activity underlying sleep-associated memory consolidation. The modulation of brain rhythms, for instance the sleep slow oscillation (SO) is used both to investigate neurophysiological mechanisms as well as to measure the impact on presumed functional correlates. In humans, auditory closed-loop stimulation targeted to the SO Up-state successfully enhanced the slow oscillation rhythm and phase-dependent spindle activity, although effects on memory retention have varied. Here, we aim to disclose relations between stimulation induced hippocampo-thalamo-cortical activity and retention performance on a hippocampus dependent task in mice. Closed-loop acoustic stimuli applied during four SO phases always acutely increased sharp wave ripple (SPWR) activity without disrupting non-rapid eye movement (NREM) sleep. Stimulation achieved an above chance preference index for stimuli delivered across a 3 h retention interval of sleep at the SO Up-state and at the Down-to-Up-state, but not at the Down-state nor late Up-state/Up-to Down-state. Results support the use of closed-loop acoustic stimulation in mice to investigate the inter-regional mechanisms underlying memory consolidation.

neuroscience↗