
Hong-Viet Victor Ngo-DehningUniversity of Essex · Department of Psychology
Hong-Viet Victor Ngo-Dehning
Diploma in Physics, PhD in Cognitive Neuroscience
About
54
Publications
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2,655
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Introduction
Additional affiliations
November 2020 - January 2021
October 2019 - October 2020
November 2013 - December 2013
Education
April 2009 - October 2014
Universität zu Lübeck, Eberhard-Karls-Universität Tübingen
Field of study
- Cognitive Neuroscience
October 2003 - December 2008
Publications
Publications (54)
Children and adults have been shown to benefit from sleep with regard to the consolidation of declarative memories. Especially during childhood, the generalisation of information from social and non‐social contexts is important for adaptable behaviour in new situations and might show specific features in children. Here, we investigated whether adul...
Sleep is essential for our physical and mental well-being. During sleep, despite the paucity of overt behavior, our brain remains active and exhibits a wide range of coupled brain oscillations. In particular slow oscillations are characteristic for sleep, however whether they are directly involved in the functions of sleep, or are mere epiphenomena...
Circadian rhythms are imprinted in all organisms and influence virtually all aspects of physiology and behaviour in adaptation to the 24-hour day-night cycle. This recognition of a circadian timekeeping system permeating essentially all healthy functioning of body and mind quickly leads to the realisation that, in turn, human ailments should be pro...
Sleep is an indispensable part of our life and plays a critical role in our physical and mental well-being. During sleep, despite the paucity of behavior, our brain stays active and exhibits a wide range of coupled brain oscillations. This activity in sleep-characteristic brain oscillations has been linked to various functions of sleep. However, wh...
The near-24 hour patterns called circadian rhythms are imprinted in all organisms and influence virtually all aspects of human physiology and behaviour. This recognition of a functioning circadian clockwork permeating essentially all healthy functioning of body and mind quickly leads to the realisation that, in turn, human ailments should be probed...
Sleep constitutes a privileged state for new memories to reactivate and consolidate. Previous work has demonstrated that consolidation can be bolstered experimentally either via delivery of reminder cues (targeted memory reactivation [TMR]) or via noninvasive brain stimulation geared toward enhancing endogenous sleep rhythms. Here, we combined both...
Several epilepsies are characterized by interictal spikes in the electroencephalogram occurring preferentially during sleep. We present a closed-loop auditory stimulation protocol with potential for treating sleep epilepsies. We describe the pre-sleep preparations, sleep recordings, the auditory stimulation, in which tones are triggered upon spike...
Sleep‐dependent memory consolidation is disturbed in patients with schizophrenia, who furthermore show reductions in sleep spindles and probably also in delta power during sleep. The memory dysfunction in these patients is one of the strongest markers for worse long‐term functional outcome. However, therapeutic interventions to normalise memory fun...
Benign epilepsy with centrotemporal spikes (BECTS) is a common form of childhood epilepsy linked to diverse cognitive abnormalities. The electroencephalogram of patients shows focal interictal epileptic spikes, particularly during non-rapid eye movement (NonREM) sleep. Spike formation involves thalamocortical networks, which also contribute to the...
Auditory closed-loop stimulation has gained traction in recent years as a means of enhancing slow oscillatory activity and, consequently, sleep-associated memory consolidation. Previous studies on this topic have primarily focused on the consolidation of semantically-congruent associations. In this study, we investigated the effect of auditory clos...
The accumulation of amyloid-β, a metabolic residue found in the brain, has been linked to cognitive ageing and Alzheimer's disease. A longitudinal study reveals that the increase of amyloid-β can be predicted using simple sleep parameters.
Auditory closed-loop stimulation is a non-invasive technique that has been widely used to augment slow oscillations during non-rapid eye movement sleep. Based on the principles of closed-loop stimulation, we developed a novel protocol for manipulating theta activity (3-7 Hz) in rapid eye movement (REM) sleep. Sixteen healthy young adults were studi...
Emotions have an important survival function. Vast amounts of research have demonstrated how affect-related changes in physiology promote survival by effecting short-term and long-term changes in adaptive behavior. However, if emotions truly serve such an inherent function, they should be pervasive across species and be established early in life. H...
Sleep is pivotal for memory consolidation. According to two-stage accounts, memory traces are gradually translocated from hippocampus to neocortex during non-rapid-eye-movement (NREM) sleep. Mechanistically, this information transfer is thought to rely on interactions between thalamocortical spindles and hippocampal ripples. To test this hypothesis...
Sleep is pivotal for memory consolidation. According to two-stage accounts, memory traces are gradually translocated from hippocampus to neocortex during non-rapid-eye-movement (NREM) sleep. Mechanistically, this information transfer is thought to rely on interactions between thalamocortical spindles and hippocampal ripples. To test this hypothesis...
Study Objectives
Cortical slow oscillations (SOs) and thalamo-cortical sleep spindles hallmark slow wave sleep and facilitate memory consolidation, both of which are reduced with age. Experiments utilising auditory closed-loop stimulation to enhance these oscillations showed great potential in young and older subjects. However, the magnitude of res...
Study Objectives: Cortical slow oscillations (SOs) and thalamo-cortical sleep spindles hallmark slow wave sleep and facilitate memory consolidation, both of which are reduced with age. Experiments utilising auditory closed-loop stimulation to enhance these oscillations showed great potential in young and older subjects. However, the magnitude of re...
Study objectives
Slow oscillations (SO) during slow-wave sleep foster the consolidation of declarative memory. Children with ADHD display deficits in the sleep-associated consolidation of declarative memory, possibly due to an altered function of SO. The present study aimed at enhancing SO activity using closed-looped acoustic stimulation during sl...
Sleep deprivation increases rates of forgetting in episodic memory. Yet, whether an extended lack of sleep alters the qualitative nature of forgetting is unknown. We compared forgetting of episodic memories across intervals of overnight sleep, daytime wakefulness and overnight sleep deprivation. Item-level forgetting was amplified across daytime wa...
Study Objectives
Closed loop auditory stimulation (CLAS) is a method for enhancing slow oscillations (SOs) through the presentation of auditory clicks during sleep. CLAS boosts SOs amplitude and sleep spindle power, but the optimal timing for click delivery remains unclear. Here, we determine the optimal time to present auditory clicks to maximise...
Background
Cortical slow oscillations (SOs) and thalamo-cortical sleep spindles hallmark slow wave sleep and facilitate sleep-dependent memory consolidation. Experiments utilising auditory closed-loop stimulation to enhance these oscillations have shown great potential in young and older subjects. However, the magnitude of responses has yet to be c...
During sleep, the time-compressed replay of engrams acquired during preceding wakefulness drives memory consolidation. We demonstrate in healthy humans that direct electrical coupling between neurons via gap junctions, i.e., electrical synapses, contributes to this beneficial effect of sleep. Twenty male participants learned a declarative word-pair...
Background: Previous research has attempted to enhance NREM sleep with various methods for greater physiological, psychological, and cognitive gain. The ability of individuals to self-enhance aspects of their sleep by anticipating such effects from outside intervention without actually receiving any has been demonstrated in insomniacs, but remains...
Slow oscillations and delta waves are neuronal activity rhythms that hallmark sleep, but until now their respective functional roles have been impossible to tease apart. Utilizing a closed-loop optogenetic approach in rats, Kim et al. (2019) dissociated the functions of these two canonical rhythms, showing they support the consolidation and forgett...
Sleep is pivotal for the consolidation of memories [1]. According to two-stage accounts, experiences are temporarily stored in the hippocampus and gradually translocated to neocortical sites during non-rapid-eye-movement (NREM) sleep [2,3]. Mechanistically, information transfer is thought to rely on interactions between thalamocortical spindles and...
Significance
Slow oscillations and spindles are hallmarks of the EEG during slow-wave sleep. They are thought to support memory consolidation, particularly in instances where the faster spindle nests into the “upstate” of a slow oscillation. Using two-photon and wide-field imaging, we recorded calcium transients from distinct populations of cortica...
Background:
The consolidation of sleep-dependent memories is mediated by an interplay of cortical slow oscillations (SOs) and thalamo-cortical sleep spindles. Whereas an enhancement of SOs with auditory closed-loop stimulation has been proven highly successful, the feasibility to induce and boost sleep spindles with auditory stimulation remains un...
Impaired sleep quality and sleep loss compromise glucose homeostasis and metabolic function, but the mechanisms linking sleep and metabolic health are largely unclear. In order to gain insight into the relevance of specific electrophysiological sleep characteristics for metabolic control, we assessed the acute effect on glucose homeostasis as well...
Sleep is essential for health. Slow wave sleep (SWS), the deepest sleep stage hallmarked by electroencephalographic slow oscillations (SOs), appears of particular relevance here. SWS is associated with a unique endocrine milieu comprising minimum cortisol and high aldosterone, growth hormone (GH), and prolactin levels, thereby presumably fostering...
A region of the brain called the putamen has a central role in procedural memory consolidation during sleep.
While the interaction of the cardinal rhythms of non-rapid-eye-movement (NREM) sleep—the thalamo-cortical spindles, hippocampal ripples, and the cortical slow oscillations—is thought to be critical for memory consolidation during sleep, the role spindles play in this interaction is elusive. Combining optogenetics with a closed-loop stimulation appr...
Slow wave activity (SWA, 0.5–4 Hz) represents the predominant EEG oscillatory activity during slow wave sleep (SWS). Its amplitude is considered in part a reflection of synaptic potentiation in cortical networks due to encoding of information during prior waking, with higher amplitude indicating stronger potentiation. Previous studies showed that i...
Author
Sleep plays a pivotal role for the consolidation of memory. While REM sleep had originally been the focus of research due to its similarity with wakefulness, more recent studies suggest that different sleep stages are responsible for the consolidation of different types of memory. To better understand the changes in neuronal dynamics betwee...
Parameter values.
This table defines all constants used throughout this paper.
(PDF)
Experimental data.
This dataset includes the experimental data used for Figs 6 and 7. Given are the time-locked averages for every subject. In Fig 6 only the sham condition was used to represent endogenous KCs/SOs, whereas Fig 7 displays the stimulation condition. For detailed information on data acquisition and processing please see the original s...
Approximation of long range connection delay.
This section provides a justification of the approximation of the thalamocortical transmission delay by a convolution with an alpha function.
(PDF)
Model equations.
This section provides the full mathematical description of the model presented here.
(PDF)
ABSTRACT: Background. N2 sleep spindles have been frequently linked to sleep-dependent memory consolidation in healthy adults. Sleep spindles (9–15 Hz) increase during sleep after learning and correlate positively with the memory retention rate. Objectives. As memory consolidation is impaired, but not completely absent, in patients suffering from o...
The <1 Hz EEG slow oscillation (SO) is a hallmark of slow-wave sleep (SWS) and is critically involved in sleep-associated memory formation. Previous studies showed that SOs and associated memory function can be effectively enhanced by closed-loop auditory stimulation, when clicks are presented in synchrony with upcoming SO up states. However, incre...
Deep sleep is characterized by two hallmarks, namely K-complexes (KCs) during sleep stage N2 and
cortical slow oscillations (SOs) during sleep stage N3. While the underlying dynamics on the neuronal
level is well known and can be easily measured, the resulting behavior on the macroscopic population
level remains unclear. On the basis of an extended...
There exists a large body of evidence pointing to an essential role of sleep in memory consolidation [1-3]. In particular non-REM sleep seems to be important for consolidating declarative memories [4]. Boosting the so-called slow oscillations (<1 Hz) during non-REM sleep via transcranial electric stimulation leads to a potentiation of memory [5]. I...
Brain rhythms regulate information processing in different states to enable learning and memory formation. The <1 Hz sleep slow oscillation hallmarks slow-wave sleep and is critical to memory consolidation. Here we show in sleeping humans that auditory stimulation in phase with the ongoing rhythmic occurrence of slow oscillation up states profoundl...
We study the discrete dynamics of a fully connected network of threshold elements interacting via dynamically evolving synapses displaying spike timing dependent plasticity. Dynamical mean-field equations, which become exact in the thermodynamical limit, are derived to study the behavior of the system driven with uncorrelated and correlated Gaussia...
Slow oscillations are electrical potential oscillations with a spectral peak frequency of ∼0.8 Hz, and hallmark the electroencephalogram during slow-wave sleep. Recent studies have indicated a causal contribution of slow oscillations to the consolidation of memories during slow-wave sleep, raising the question to what extent such oscillations can b...
We hypothesize that the type of cortical network activation influences synaptic connectivity in the network, eventually expressed in an altered responsiveness to external stimuli. Our predictions are based on a time discrete canonical model of spike-time–dependent plasticity. The results show that, at a given synaptic connection strength in the net...
Slow-wave sleep in mammalians is characterized by a change of large-scale cortical activity currently paraphrased as cortical Up/Down states. A recent experiment demonstrated a bistable collective behaviour in ferret slices, with the remarkable property that the Up states can be switched on and off with pulses, or excitations, of same polarity; whe...
In a recent experiment [1] investigated the on-and off switching of bursting activity in ferret brain slices. This experiment is seen as a paradigmatic system towards the understanding of the emergence of cortical slow waves. The basic dynamics can be modeled by a simplified discretized integrate-and-fire model having intrinsic inhibitory currents...