Björn Rasch

University of Fribourg · Département de psychologie

Sleep associated memory consolidation and reactivation play an important role in language acquisition and learning of new words. However, it is unclear to what extent properties of word learning difficulty impact sleep associated memory reactivation. To address this gap, we investigated in 22 young healthy adults the effectiveness of auditory targe...

The active system consolidation theory assumes that sleep between encoding and retrieval promotes memory consolidation. In the present study, we cued new memories during slow-wave (SWS) or rapid eye movements (REM) sleep stages by presenting an instrumental music stimuli that had been previously presented during a learning session. In a within-subj...

The first night in an unfamiliar environment is marked by reduced sleep quality and changes in sleep architecture. This so-called First-Night Effect (FNE) is well established for two consecutive nights and lays the foundation for including an adaptation night in sleep research to counteract FNEs. However, adaptation nights rarely happen immediately...

Introduction The HGSHS:A is one of the most commonly used measures of hypnotic suggestibility. However, this test suffers from low feasibility due to a time requirement exceeding 1 h, and from a questionable representation of the normal population. Recently, a short version of HGSHS-5:G was developed and published, and now the first results are ava...

Theta oscillations support memory formation, but their exact contribution to the communication between prefrontal cortex (PFC) and the hippocampus is unknown. We tested the functional relevance of theta oscillations as a communication link between both areas for memory formation using transcranial alternating current stimulation (tACS). Healthy, yo...

Sleep associated memory consolidation and reactivation play an important role in language acquisition and learning of new words. However, it is unclear to what extent properties of word learning difficulty impact sleep associated memory reactivation. To address this gap, we investigated in twenty-two young healthy adults the effectiveness of audito...

Targeted memory reactivation (TMR) is an effective technique to enhance sleep-associated memory consolidation. The successful reactivation of memories by external reminder cues is typically accompanied by an event-related increase in theta oscillations, preceding better memory recall after sleep. However, it remains unclear whether the increase in...

Introduction Hypnotizability is conceptualized as a stable personality trait describing the ability to respond to suggestions given under hypnosis. Hypnotizability is a key factor in explaining variance in the effects of hypnotic suggestions on behavior and neural correlates, revealing robust changes mostly in high hypnotizable participants. Howeve...

Study Objectives Voluntary sleep restriction is a common phenomenon in industrialized societies aiming to increase time spent awake and thus productivity. We explored how restricting sleep to a radically polyphasic schedule affects neural, cognitive, and endocrine characteristics. Methods Ten young healthy participants were restricted to one 20-mi...

Sleep associated memory consolidation and reactivation play an important role in language acquisition and learning of new words. However, it is unclear to what extent properties of word learning difficulty impact sleep associated memory reactivation. To address this gap, we investigated in twenty-two young healthy adults the effectiveness of audito...

In adults there are indications that regular eating patterns are related to better sleep quality. During early development, sleep and eating habits experience major maturational transitions. Further, the bacterial landscape of the gut microbiota undergoes a rapid increase in complexity. Yet little is known about the association between sleep, eatin...

Sleep supports memory consolidation, and slow-wave sleep (SWS) in particular is assumed to benefit the consolidation of verbal learning material. Re-exposure to previously learned words during SWS with a technique known as targeted memory reactivation (TMR) consistently benefits memory. However, TMR has also been successfully applied during sleep s...

Sleep associated memory consolidation and reactivation play an important role in language acquisition and learning of new words. However, it is unclear to what extent properties of word learning difficulty impact sleep associated memory reactivation. To address this gap, we investigated in twenty-two young healthy adults the effectiveness of audito...

Voluntary sleep restriction is a common phenomenon in industrialized societies aiming to increase time spent awake and thus productivity. We explored how restricting sleep to a radically polyphasic schedule affects neural, cognitive, and endocrine characteristics. Ten young healthy participants were restricted to one 30-min nap opportunity at the e...

Recent findings indicate that sleep after trauma compared to sleep loss inhibits intrusive memory development, possibly by promoting adequate memory consolidation and integration. However, the underlying neural mechanisms are still unknown. Here, we examined the neural correlates underlying the effects of sleep on traumatic memory development in 11...

Errata: Just to let you know that in the discussion, one of the arguments is not our current one. "-results from online-tACS (tACS during the task) let assume that an unintentional interruption of a required theta-based communication between left and right hemisphere occured due to 180° phase difference between electrodes of different hemispheres...

Background Evidence-based treatments of posttraumatic stress disorder (PTSD) aim to promote fear extinction learning. Post-learning sleep, particularly slow wave sleep (SWS), promotes memory consolidation and recall. Thus, boosting SWS might strengthen extinction recall. The current study investigated whether sleep-directed hypnosis designed to inc...

Sleep‐mediated memory benefits are modulated by several factors. Prior knowledge is assumed critical for consolidation during sleep, despite inconclusive empirical findings. Additionally, prior knowledge facilitates encoding, leading to differences in memory strength already before the retention filled with sleep. We tested whether increasing memor...

Pre-sleep arousal impairs sleep. Therefore, watching suspenseful TV series before sleep is not recommended as they increase arousal. In particular, the consumption of multiple episodes of the same suspenseful TV series in one sitting – termed Binge Watching – could lead to large increases in physiological arousal delaying sleep onset. Furthermore,...

Recent advancements in real‐time brain stimulation in the sleep field have led to many exciting findings. However, they have also opened up terminological ambiguities about what constitutes “open‐loop”, “closed‐loop”, and “real‐time” designs. Here, we address core theoretical aspects of these terms in the hopes of strengthening future research on t...

Background: Pre-sleep intentions to react to stimuli during sleep affect sleep processes in spite of reductions in conscious awareness. Here, we compare influences of sounds presented during sleep (with and without intentions to react) with the effect of pre-sleep intentions on sleep (with and without sounds being present during sleep). Methods:...

When individuals score high on hypnotizability, they usually report experiencing an altered state of consciousness, physiological changes, and attentional shifts during hypnotic induction procedures as well. We hypothesize that a better interoception of such internal changes is also relevant for accurate sleep perception. We compared subjects scori...

Real‐time brain stimulation is a powerful technique that continues to gain importance in the field of sleep and cognition. In this special issue, we collected 14 articles about real‐time stimulation during sleep, including one review, 12 research articles and one letter covering both human and rodent research from various fields. We hope this speci...

Sleep is important for normal brain and body functioning, and for this, slow-wave sleep (SWS), the deepest stage of sleep, is assumed to be especially relevant. Previous studies employing methods to enhance SWS have focused on central nervous components of this sleep stage. However, SWS is also characterized by specific changes in the body peripher...

Successful learning or recall of information correlates positively with increased activity in the theta frequency band. It is assumed that theta serves as a key element in the bi-directional interaction between prefrontal cortex (PFC) and hippocampus (HPC). However, a functional relevance of theta for memory formation has not yet been shown. Theref...

The anticipation of a future stressor can increase worry and cognitive arousal and has a detrimental effect on sleep. Similarly, experiencing a stressful event directly before sleep increases physiological and cognitive arousal and impairs subsequent sleep. However, the effects of post- vs. pre-sleep stress on sleep and their temporal dynamics have...

Cliffhangers are a common style element in serial entertainment. This study investigates their role in today’s high-choice media environment. It is assumed that cliffhangers lead to higher arousal, increase the enjoyment of a series, and foster the intention to continue watching. This may foster binge-watching or, more generally, high-intensity vie...

Dieses Kapitel beschäftigt sich mit Verfahren, mit denen sich der statistische Zusammenhang von Merkmalen ausdrücken und statistisch bewerten lässt. Im ersten Hauptteil des Kapitels werden verschiedene Korrelationstechniken je nach Skalenniveau der untersuchten Variablen vorgestellt (z. B. Produkt-Moment-Korrelation, punktbiseriale Korrelation, Ran...

Dieses Kapitel geht näher auf die Verteilungseigenschaften gemessener Merkmale ein und legt damit den Grundstein für die sogenannte „schließende Statistik“. Im Mittelpunkt steht die Normalverteilung, die bei vielen statistischen Verfahren vorausgesetzt wird. Zunächst werden die Verteilungseigenschaften der Normalverteilung und die damit mögliche Be...

Dieser Kapitel behandelt den t-Test, ein zentrales statistisches Auswertungsverfahren für den Vergleich zweier Gruppenmittelwerte. Dabei wird zunächst ausführlich auf alle dem t-Test für unabhängige Stichproben zugrunde liegenden Annahmen (z. B. Nullhypothese versus Alternativhypothese), statistischen Konzepte (z. B. t-Verteilung, Freiheitsgrade) u...

Dieses Kapitel führt zunächst ein in die Organisation von Daten in einer Datenmatrix und die Darstellung von Daten mithilfe einfacher Diagrammtypen. Anschließend werden die verschiedenen Skalentypen (Nominalskala, Ordinalskala, Intervallskala, Verhältnisskala) vorgestellt und die ihnen zugrunde liegenden Annahmen diskutiert und verglichen. Der drit...

Dieses Kapitel behandelt die einfaktorielle Varianzanalyse (ANOVA), die sich zur statistischen Analyse der Mittelwertsunterschiede mehrerer Gruppen eignet. Zunächst wird das Grundprinzip der ANOVA verdeutlicht, die Zerlegung der Gesamtvarianz in systematische (Zwischenvarianz) und unsystematische Einflüsse (Residualvarianz). Daraus wird die statist...

Sogenannte nichtparametrische Verfahren werden verwendet, wenn die Intervallskalenqualität der Messwerte nicht gegeben ist. Dieses Kapitel stellt drei statistische Auswertungsverfahren vor, die sich auf die Analyse von Daten auf Ordinalskalenniveau beziehen: den U-Test für unabhängige Stichproben von Mann-Whitney (das Pendant zum t-Test für unabhän...

Dieses Kapitel führt ein in die Varianzanalyse mit Messwiederholung, einer Erweiterung des t-Tests für abhängige Stichproben (Kap. 3, Band 1). Dabei wird sowohl auf die einfaktorielle Varianzanalyse mit Messwiederholung als auch auf zweifaktorielle Versuchspläne mit Messwiederholung auf einem Faktor oder beiden Faktoren eingegangen. Für jeden diese...

Dieses Kapitel behandelt die Chi-Quadrat-Verfahren (χ²-Verfahren), eine Familie nichtparametrischer statistischer Verfahren, die sich zur Analyse (nominalskalierter) Häufigkeitsdaten eignen. Das gemeinsame Prinzip dieser Familie ist der Vergleich beobachteter und theoretisch erwarteter Häufigkeiten. Für drei typisch anzutreffende Verfahren (der ein...

Dieses Kapitel setzt sich mit der zweifaktoriellen Varianzanalyse auseinander, einer Erweiterung der einfaktoriellen Varianzanalyse um einen zusätzlichen Faktor. Zunächst werden die drei Arten von Effekten (Haupteffekt A, Haupteffekt B, Wechselwirkung A×B) und deren Prüfung auf Signifikanz erläutert sowie Effektstärke, Teststärkeanalyse und Stichpr...

Master's thesis abstract: Declarative memory performance can be improved under theta transcranial alternating current stimulation (tACS) or targeted memory reactivation (TMR). Recent studies had shown that theta rhythms are closely linked to memory encoding, consolidation and retrieval processes, and that theta-tACS can enhance memory performance...

Objective Sleep is critical for our mental health and optimal cognitive functioning. Social media use is increasingly common and suspected to disturb sleep due to increasing bedtime arousal. However, most studies rely on self-reported sleep. Methods We tested the effects of 30 min social media use on arousal and subsequent sleep in the sleep labor...

Purpose Sleep, in particular slow-wave sleep, is beneficial for memory consolidation. In two recent studies, a hypnotic suggestion to sleep more deeply increased the amount of slow-wave sleep in both a nap and a night design. In spite of these increases in slow-wave sleep, no beneficial effect on declarative memory consolidation was found. As coupl...

Traumatic events can produce emotional, cognitive and autonomous physical responses. This may ultimately lead to post-traumatic stress disorder (PTSD), a psychiatric syndrome which requires comprehensive treatment. Trauma exposure alters functional connectivity; however, onset and nature of these changes are unknown. Here, we explore functional con...

Understanding human sleep requires appropriate animal models. Sleep has been extensively studied in rodents, although rodent sleep differs substantially from human sleep. Here we investigate sleep in tree shrews, small diurnal mammals phylogenetically close to primates, and compare it to sleep in rats and humans using electrophysiological recording...

Our thoughts alter our sleep, but the underlying mechanisms are still unknown. We propose that mental processes are active to a greater or lesser extent during sleep and that this degree of activation affects our sleep depth. We examined this notion by activating the concept of “relaxation” during sleep using relaxation-related words in 50 healthy...

Introduction Cognitive processes (e.g., rumination, perception of an unfamiliar sleeping environment, relaxation techniques) alter our sleep, but the underlying mechanisms are still unknown. Theories of embodied or grounded cognition assume that semantic meaning is stored in multimodal neuronal networks. We therefore assume that cognitive concepts...

Our thoughts can influence sleep, but the underlying mechanisms are unknown. According to the theory of "embodied cognition," the semantic content of cognitive processes is represented by multimodal networks in the brain, which include body-related functions. Such multimodal representations could offer a mechanism, which explains mutual influences...

Memories benefit from a retention interval filled with sleep. Current theories assume that this beneficial effect relies on consolidation processes occurring during slow-wave sleep (SWS). However, in the last years, several key findings supporting these theories could not be replicated or occurred only under certain conditions, suggesting that effe...

Study Objectives Memory consolidation benefits from a retention period filled with sleep. Several theoretical accounts assume that slow-wave sleep (SWS) contributes functionally to processes underlying the stabilization of declarative memories during sleep. However, reports on correlations between memory retention and the amount of SWS are mixed an...

Dieses Lehrbuch macht Dich fit für die Statistik-Prüfung – hier geht es um die Deskriptive Statistik sowie um die ersten Schritte in Inferenzstatistik, z.B. den t-Test. Also Dinge, die in vielen sozialwissenschaftlichen Studiengängen, wie z.B. Psychologie, Soziologie oder Erziehungswissenschaften, auf dem Lehrplan stehen. Vielen macht die Statistik...

Dieses Lehrbuch macht Dich fit für die Statistik-Prüfung – hier geht es u.a. um Varianzanalysen und Verfahren für Rang- und Nominaldaten. Also Dinge, die in vielen sozialwissenschaftlichen Studiengängen, wie z.B. Psychologie, Soziologie oder Erziehungswissenschaften, auf dem Lehrplan stehen. Mit diesem Buch wirst Du die Prüfung meistern, weil Dir h...

Our thoughts, plans and intentions can influence physiological sleep, but the underlying mechanisms are unknown. According to the theoretical framework of “embodied cognition”, the semantic content of cognitive processes is represented by multimodal networks in the brain which also include body-related functions. Such multimodal representation coul...

Our thoughts alter our sleep, but the underlying mechanisms are still unknown. We propose that mental processes are active to a greater or lesser extent during sleep and that this degree of activation affects our sleep depth. We examined this notion by activating the concept of “relaxation” during sleep using relaxation-related words in 50 healthy...

Purpose Sleep is regulated by homeostatic and circadian factors. In addition, psychological factors have a strong modulatory impact on our sleep, but the exact underlying mechanisms are still largely unknown. Here, we examined the role of intentions on subjective and objective sleep parameters. Young healthy sleepers were instructed to voluntarily...

When a stimulus is important, the corresponding brain responses increase, especially the P300 brain response. This is true for all kinds of important stimuli, also monetary rewards. In our study, we developed a hypnotic suggestion to reduce the subjective importance of monetary rewards. As successful suggestions do not contain negations, we suggest...

The reliable induction of lucid dreams is a challenge in lucid dream research. In a previous study by our research group we were able to induce in about 50% of the participants a lucid dream in a single sleep laboratory night by combining a wake-up-back-to-bed sleep protocol and a mnemonic technique. In the present study, we extended our previous p...

During sleep, our memories are spontaneously reactivated and consolidated. Now it seems that we can influence these reactivations in specific locations of our brain, for example, by sniffing memory-related odors with only one nostril.

Re-exposure of newly acquired vocabulary during sleep improves later memory recall in healthy adults. The success of targeted memory reactivation (TMR) during sleep presumably depends on the presence of slow oscillations (i.e., EEG activity at a frequency of about 0.75 Hz). As slow oscillating activity is at its maximum during adolescence, we hypot...

Sleep benefits the stabilization of newly acquired information – a process known as memory consolidation. Age-related alterations in sleep physiology may affect memory consolidation and account for reduced episodic memory performance in healthy older individuals. The striking parallelism of age-related changes in sleep and episodic memory has provo...

While slow-wave sleep (SWS) is fundamental for maintaining health and well-being, it is typically reduced with stress or age. The authors have previously reported that hypnotic suggestions before sleep increased SWS duration and slow-wave activity (SWA) during a midday nap in hypnotizable younger and older women. To test generalizability, they inve...

Successful consolidation of associative memories relies on the coordinated interplay of slow oscillations and sleep spindles during non-rapid eye movement (NREM) sleep. This enables the transfer of labile information from the hippocampus to permanent memory stores in the neocortex. During senescence, the decline of the structural and functional int...

Background: It is assumed that the memory function of sleep relies on the spontaneous reactivation of newly acquired memories. Those spontaneous reactivation processes are driven by the cortical slow oscillations, while inducing memory reactivations by re-exposure to learning-associated memory cues (TMR) results in enhanced memory performance. Slow...

Sleep is vital for human health and wellbeing, and sleep disturbances are comorbid to many mental and physiological disorders. Music consistently improves subjective sleep quality, whereas results for objective sleep parameters diverge. These inconsistencies might be due to inter-individual differences. Here, 27 female subjects listened to either m...

Phase-amplitude coupling is a promising construct to study cognitive processes in electroencephalography (EEG) and magnetencephalography (MEG). Due to the novelty of the concept, various measures are used in the literature to calculate phase-amplitude coupling. Here, performance of the three most widely used phase-amplitude coupling measures – phas...

Targeted memory reactivation (TMR) during sleep improves memory consolidation. However, it is still unknown whether TMR also benefits memory in real-life conditions. We tested whether TMR during sleep enhances Dutch-German vocabulary learning when applied during multiple nights at home in an unsupervised fashion. During 3 consecutive nights, 66 hea...

Increased neuronal signatures of targeted memory reactivation during slow-wave up-states

Intrusive memories are a key symptom of post‐traumatic stress disorder (PTSD). They emerge early after trauma exposure and are predictive for PTSD development. There is a high relevance in evaluating the neurobiological mechanisms of early stages of intrusive symptom development to provide a further understanding of PTSD. In the present study, we e...

It is assumed that slow oscillatory up-states represent crucial time windows for memory reactivation and consolidation during sleep. We tested this assumption by utilizing closed-loop targeted memory reactivation: Participants were re-exposed to prior learned foreign vocabulary during up- and down-states of slow oscillations. While presenting memor...

Memory consolidation during sleep relies on the precisely timed interaction of rhythmic neural events. Here, we investigate differences in slow oscillations (SO; 0.5–1 Hz), sleep spindles (SP), and their coupling across the adult human lifespan and ask whether observed alterations relate to the ability to retain associative memories across sleep. W...

Successful consolidation of associative memories relies on the coordinated interplay of slow oscillations and sleep spindles during non-rapid eye movement (NREM) sleep, enabling the transfer of labile information from the hippocampus to permanent memory stores in the neocortex. During senescence, the decline of the structural and functional integri...

Sleep disturbances are an important risk factor for stress-related diseases such as burnout or depression. In particular, slow-wave activity (SWA) during sleep might be eminently relevant for optimal maintenance of mental health and cognitive functioning. In spite of the clinical importance and the pertinence of stress-related processes in everyday...

Reactivating brain activity patterns during sleep enhances memory performance the next day.