032 Sleep Consolidates Memory for Strong but not Weak Information After Incidental Encoding

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A14-A15
Author(s):  
Elle Wernette ◽  
Kimberly Fenn
Keyword(s):  
Slow Wave ◽  
Response Latency ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Memory Performance ◽  
Memory Test ◽  
Memory Strength ◽  
Memory Traces ◽  
Incidental Encoding ◽  
The Relationship

Abstract Introduction Slow wave sleep (SWS) strengthens memory for studied information, but research on the effect of sleep on information that is not intentionally remembered is scarce. Previous research from our lab suggests sleep consolidates some information that has been encoded incidentally, meaning that it has been acted on but not intentionally remembered. It remains unclear what determines which information is consolidated during sleep after incidental encoding and what aspects of sleep are related to this mnemonic benefit. In two experiments, we test the hypothesis that sleep consolidates strong but not weak memory traces following incidental encoding and assess the relationship between memory performance and sleep attributes. Methods In Experiment 1, we manipulated memory strength within- and between-subjects. Participants rated words one or three times (within) in a shallow or deep incidental encoding task (between). In the shallow task, participants counted vowels in each word; in the deep task, participants rated each word on a scale from ‘concrete’ to ‘abstract’. Following a 12-hour period containing sleep or wakefulness, participants took a surprise memory test. In Experiment 2, participants rated words one or three times in the deep encoding task, received an 8-hour sleep opportunity with partial PSG, and took the surprise memory test. Results In Experiment 1, participants remembered words better after sleep than wake regardless of number of encoding trials, but only after deep encoding. There was not an effect of sleep following shallow encoding. In Experiment 2, SWS correlated negatively with response latency for correctly recognized words encoded once, but not those encoded three times. That is, participants who received more SWS showed faster performance. Conclusion Results suggest sleep consolidated information based on the depth of encoding, and this benefit was related to SWS. This work is broadly consistent with theories of memory consolidation that predict sleep is more beneficial for strong than weak memory traces, such as the synaptic downscaling hypothesis. Support (if any):

scholarly journals 0084 Sleep Consolidates Incidentally Encoded Information After Deep but Not Shallow Encoding

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A34-A34
Author(s):  
E M Wernette ◽  
K M Fenn
Keyword(s):  
Slow Wave ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Declarative Memory ◽  
Memory Performance ◽  
Memory Test ◽  
Memory Traces ◽  
Incidental Encoding ◽  
The Relationship ◽  
With Memory

Abstract Introduction Slow wave sleep (SWS) strengthens declarative memory for information studied for a later test. However, research on the effect of sleep on information that is not intentionally remembered is scare. Previous research from our lab suggests sleep consolidates some, but not all, information that has been encoded incidentally, meaning that it has been acted on but not intentionally remembered. It remains unclear what determines which information benefits from sleep-dependent consolidation processes and what aspects of sleep are related to these mnemonic benefits. In two experiments, we test the hypothesis that sleep consolidates strong but not weak memory traces following incidental encoding, and assess the relationship between memory performance and objective sleep characteristics. Methods In Experiment 1, participants rated words one (weak traces) or three times (strong traces) in a deep or shallow incidental encoding task. Participants either rated words on a scale from ‘concrete’ to ‘abstract’ (deep) or counted the vowels in the words (shallow). Following a 12-hour period containing sleep or wakefulness, participants took a surprise memory test. In Experiment 2, participants rated words one or three times in the deep encoding task, received an 8-hour sleep opportunity with polysomnography, and took the surprise memory test. Results In Experiment 1, participants remembered words better after sleep than wake regardless of whether words were encoded one or three times, but only after deep encoding. Sleep did not consolidate information following shallow encoding. Experiment 2 is ongoing, but we predict that the amount of SWS will correlate positively with memory. Conclusion Results thus far suggest sleep may have consolidated information based on the strength of memory traces. Because deep encoding results in stronger memory traces than shallow encoding, this work is broadly consistent with theories of memory consolidation that predict sleep is more beneficial for strong memory traces than weak, such as the synaptic downscaling hypothesis. Support N/A

scholarly journals Bi-Temporal Anodal Transcranial Direct Current Stimulation during Slow-Wave Sleep Boosts Slow-Wave Density but Not Memory Consolidation

2021 ◽  
Vol 11 (4) ◽  
pp. 410
Author(s):  
Simon Ruch ◽  
Kristoffer Fehér ◽  
Stephanie Homan ◽  
Yosuke Morishima ◽  
Sarah Maria Mueller ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Slow Wave ◽  
Direct Current ◽  
Memory Consolidation ◽  
Transcranial Direct Current Stimulation ◽  
Slow Wave Sleep ◽  
Memory Performance ◽  
Direct Current Stimulation ◽  
Sleep Parameters ◽  
Episodic Memories

Slow-wave sleep (SWS) has been shown to promote long-term consolidation of episodic memories in hippocampo–neocortical networks. Previous research has aimed to modulate cortical sleep slow-waves and spindles to facilitate episodic memory consolidation. Here, we instead aimed to modulate hippocampal activity during slow-wave sleep using transcranial direct current stimulation in 18 healthy humans. A pair-associate episodic memory task was used to evaluate sleep-dependent memory consolidation with face–occupation stimuli. Pre- and post-nap retrieval was assessed as a measure of memory performance. Anodal stimulation with 2 mA was applied bilaterally over the lateral temporal cortex, motivated by its particularly extensive connections to the hippocampus. The participants slept in a magnetic resonance (MR)-simulator during the recordings to test the feasibility for a future MR-study. We used a sham-controlled, double-blind, counterbalanced randomized, within-subject crossover design. We show that stimulation vs. sham significantly increased slow-wave density and the temporal coupling of fast spindles and slow-waves. While retention of episodic memories across sleep was not affected across the entire sample of participants, it was impaired in participants with below-average pre-sleep memory performance. Hence, bi-temporal anodal direct current stimulation applied during sleep enhanced sleep parameters that are typically involved in memory consolidation, but it failed to improve memory consolidation and even tended to impair consolidation in poor learners. These findings suggest that artificially enhancing memory-related sleep parameters to improve memory consolidation can actually backfire in those participants who are in most need of memory improvement.

scholarly journals Stimulation augments spike sequence replay and memory consolidation during slow-wave sleep

2019 ◽  
Author(s):  
Yina Wei ◽  
Giri P Krishnan ◽  
Lisa Marshall ◽  
Thomas Martinetz ◽  
Maxim Bazhenov
Keyword(s):  
Slow Wave ◽  
Memory Consolidation ◽  
Temporal Pattern ◽  
Slow Wave Sleep ◽  
Sensory Stimulation ◽  
Slow Waves ◽  
Memory Traces ◽  
Spatio Temporal ◽  
Synaptic Level

AbstractNewly acquired memory traces are spontaneously reactivated during slow-wave sleep (SWS), leading to the consolidation of recent memories. Empirical studies found that sensory stimulation during SWS selectively enhances memory consolidation and the effect depends on the phase of stimulation. In this new study, we aimed to understand the mechanisms behind the role of sensory stimulation on memory consolidation using computational models implementing effects of neuromodulators to simulate transitions between awake and SWS sleep, and synaptic plasticity to allow the change of synaptic connections due to the training in awake or replay during sleep. We found that when closed-loop stimulation was applied during the Down states (900-2700) of sleep slow oscillation, particularly right before transition from Down to Up state, it significantly affected the spatio-temporal pattern of the slow-waves and maximized memory replay. In contrast, when the stimulation was presented during the Up states (2700-3600 and 00-900), it did not have a significant impact on the slow-waves or memory performance after sleep. For multiple memories trained in awake, presenting stimulation cues associated with specific memory trace could selectively augment replay and enhance consolidation of that memory and interfere with consolidation of the others (particularly weak) memories. Our study proposes a synaptic level mechanism of how memory consolidation is affected by sensory stimulation during sleep.Significance statementStimulation, such as training-associated cues or auditory stimulation, during sleep can augment consolidation of the newly encoded memories. In this study, we used a computational model of the thalamocortical system to describe the mechanisms behind the role of stimulation in memory consolidation during slow-wave sleep. Our study suggested that stimulation preferentially strengthens the memory traces when delivered at specific phase of slow oscillations just before Down to Up state transition when it makes the largest impact on the spatio-temporal pattern of sleep slow waves. In the presence of multiple memories, presenting sensory cues during sleep could selectively strengthen selected memories. Our study proposes a synaptic level mechanism of how memory consolidation is affected by sensory stimulation during sleep.

scholarly journals Bi-temporal anodal tDCS during slow-wave sleep boosts episodic memory consolidation in high performers

2019 ◽  
Author(s):  
Matthias Grieder ◽  
Yosuke Morishima ◽  
Stephanie Winkelbeiner ◽  
Sarah M Mueller ◽  
Kristoffer Feher ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Slow Wave ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Declarative Memory ◽  
Memory Performance ◽  
Memory Task ◽  
Anodal Tdcs ◽  
Double Blind ◽  
High Performers

Background: Sleep is crucial for sound memory functioning in humans. In particular, the slow waves that occur predominantly during slow wave sleep (SWS) are associated with hippocampus-dependent declarative memory consolidation. Making use of this association, boosting SWS to improve memory performance would be appealing for both healthy and memory-impaired populations. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation that modulates the brain’s excitability and has shown promising results in improving memory performance. However, owing to differing stimulation protocols and contradictory findings, there is insufficient evidence for the efficacy of tDCS-modulated hippocampal excitability on SWS and sleep-dependent memory consolidation.Hypotheses: We aimed to enhance sleep-dependent memory consolidation and augment slow wave amplitudes.Methods: We applied bi-temporal anodal tDCS to the left and right lateral temporal lobes of 31 healthy participants in a double-blind, sham-controlled, randomized crossover study. State-dependent tDCS was administered during slow wave sleep only. A pair-associate episodic memory task was used to assess sleep-dependent memory consolidation with face-occupation stimuli with baseline retrieval before sleep and delayed retrieval after sleep.Results: Sleep-dependent memory consolidation was increased by tDCS only in participants who showed above-average performance (i.e. high performers) in baseline memory retrieval. Moreover, tDCS increased the slow wave amplitudes compared to sham.Conclusions: When targeting a specialized brain mechanism such as memory consolidation with tDCS during slow wave sleep, only those who were high performers at baseline achieved a memory boost.

scholarly journals The modulatory effect of oscillatory reinstatement during slow-wave sleep on declarative memory consolidation

2019 ◽  
Author(s):  
Becky Crowley ◽  
Amir-Homayoun Javadi
Keyword(s):  
Slow Wave ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Declarative Memory ◽  
Memory Performance ◽  
Memory Task ◽  
Oscillatory Activity ◽  
Dorsolateral Prefrontal ◽  
Transcranial Alternating Current Stimulation ◽  
Human Participants

Consistent with the context-dependent memory literature, previous research suggests that when the same frequency of neural oscillations is reinstated between memory encoding and retrieval, engram reactivation is facilitated, and thus declarative memory recall is enhanced. Importantly, engram reactivation is also fundamental for the redistribution process that underlies sleep-dependent memory consolidation. Therefore, the current study investigated whether reinstating frequency-specific oscillatory activity between encoding and sleep would facilitate the engram reactivation implicated in sleep-dependent memory consolidation, and thus enhance post-sleep declarative memory performance. Transcranial alternating current stimulation (tACS) was administered to the left dorsolateral prefrontal cortex (DLPFC) of human participants during a declarative memory task. Participants received 60 Hz of stimulation during encoding, and 60 Hz, 90 Hz, or sham stimulation during post-learning slow-wave sleep (SWS) or rapid eye-movement (REM) sleep. In immediate and delayed free recall sessions, declarative memory performance was significantly enhanced if participants had received the same frequency of stimulation during encoding and SWS compared to any other stimulation condition. This finding supports a novel theoretical proposal, which assumes that an intrinsic neurobiological mechanism for coordinating frequency-specific oscillatory activity, during SWS, underlies sleep-dependent declarative memory consolidation.

scholarly journals Autonomic activity during sleep predicts memory consolidation in humans

2016 ◽  
Vol 113 (26) ◽  
pp. 7272-7277 ◽  
Author(s):  
Lauren N. Whitehurst ◽  
Nicola Cellini ◽  
Elizabeth A. McDevitt ◽  
Katherine A. Duggan ◽  
Sara C. Mednick
Keyword(s):  
Memory Consolidation ◽  
Memory Performance ◽  
Sleep Stages ◽  
Remote Associates Test ◽  
Daytime Nap ◽  
The Relationship ◽  
With Memory ◽  
Good Sleep ◽  
Variance Explained

Throughout history, psychologists and philosophers have proposed that good sleep benefits memory, yet current studies focusing on the relationship between traditionally reported sleep features (e.g., minutes in sleep stages) and changes in memory performance show contradictory findings. This discrepancy suggests that there are events occurring during sleep that have not yet been considered. The autonomic nervous system (ANS) shows strong variation across sleep stages. Also, increases in ANS activity during waking, as measured by heart rate variability (HRV), have been correlated with memory improvement. However, the role of ANS in sleep-dependent memory consolidation has never been examined. Here, we examined whether changes in cardiac ANS activity (HRV) during a daytime nap were related to performance on two memory conditions (Primed and Repeated) and a nonmemory control condition on the Remote Associates Test. In line with prior studies, we found sleep-dependent improvement in the Primed condition compared with the Quiet Wake control condition. Using regression analyses, we compared the proportion of variance in performance associated with traditionally reported sleep features (model 1) vs. sleep features and HRV during sleep (model 2). For both the Primed and Repeated conditions, model 2 (sleep + HRV) predicted performance significantly better (73% and 58% of variance explained, respectively) compared with model 1 (sleep only, 46% and 26% of variance explained, respectively). These findings present the first evidence, to our knowledge, that ANS activity may be one potential mechanism driving sleep-dependent plasticity.

scholarly journals Selection of stimulus parameters for enhancing slow wave sleep events with a Neural-field theory thalamocortical computational model

2021 ◽  
Author(s):  
Felipe A. Torres ◽  
Patricio Orio ◽  
María-José Escobar
Keyword(s):  
Computational Model ◽  
Slow Wave ◽  
Memory Consolidation ◽  
Closed Loop ◽  
Slow Wave Sleep ◽  
Brain Activity ◽  
Sensory Stimulation ◽  
Sleep Spindles ◽  
Slow Oscillations ◽  
Closed Loop Stimulation

AbstractSlow-wave sleep cortical brain activity, conformed by slow-oscillations and sleep spindles, plays a key role in memory consolidation. The increase of the power of the slow-wave events, obtained by auditory sensory stimulation, positively correlates to memory consolidation performance. However, little is known about the experimental protocol maximizing this effect, which could be induced by the power of slow-oscillation, the number of sleep spindles, or the timing of both events’ co-occurrence. Using a mean-field model of thalamocortical activity, we studied the effect of several stimulation protocols, varying the pulse shape, duration, amplitude, and frequency, as well as a target-phase using a closed-loop approach. We evaluated the effect of these parameters on slow-oscillations (SO) and sleep-spindles (SP), considering: (i) the power at the frequency bands of interest, (ii) the number of SO and SP, (iii) co-occurrences between SO and SP, and (iv) synchronization of SP with the up-peak of the SO. The first three targets are maximized using a decreasing ramp pulse with a pulse duration of 50 ms. Also, we observed a reduction in the number of SO when increasing the stimulus energy by rising its amplitude. To assess the target-phase parameter, we applied closed-loop stimulation at 0º, 45º, and 90º of the phase of the narrow-band filtered ongoing activity, at 0.85 Hz as central frequency. The 0º stimulation produces better results in the power and number of SO and SP than the rhythmic or aleatory stimulation. On the other hand, stimulating at 45º or 90º change the timing distribution of spindles centers but with fewer co-occurrences than rhythmic and 0º phase. Finally, we propose the application of closed-loop stimulation at the rising zero-cross point using pulses with a decreasing ramp shape and 50 ms of duration for future experimental work.Author summaryDuring the non-REM (NREM) phase of sleep, events that are known as slow oscillations (SO) and spindles (SP) can be detected by EEG. These events have been associated with the consolidation of declarative memories and learning. Thus, there is an ongoing interest in promoting them during sleep by non-invasive manipulations such as sensory stimulation. In this paper, we used a computational model of brain activity that generates SO and SP, to investigate which type of sensory stimulus –shape, amplitude, duration, periodicity– would be optimal for increasing the events’ frequency and their co-occurrence. We found that a decreasing ramp of 50 ms duration is the most effective. The effectiveness increases when the stimulus pulse is delivered in a closed-loop configuration triggering the pulse at a target phase of the ongoing SO activity. A desirable secondary effect is to promote SPs at the rising phase of the SO oscillation.

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