bluuebunny/crossref_metadata_2025_split huggingface dataset:
0063 Sleep Deprivation Impairs Short-term Object Recall on a Serial Novel Object Recognition Task in Rats
Authors: Fluke Sofia , Satterfield Brieann , Davis Christopher 
Published: April 2024

Abstract

Introduction
Novel Object Recognition (NOR) is a rodent behavioral task used to test recall based on the time taken to explore a novel versus familiar object. Sleep deprivation (SD) compromises object discrimination, but time of day and interphase interval (IPI) are important to performance. While the effects of SD on NOR have been investigated with a single object recall opportunity, SD preceding short-term recall combined with serial trials has not been reported. Serial paradigms are important for establishing baseline performance and predicting future performance altered by practice effect and habituation. Here we present a unique serial NOR paradigm that assesses baseline performance, SD, and IPI effects.

Methods
Male Sprague Dawley rats (N=20) were housed on a ZT0-ZT12 light cycle with baseline NOR testing at ZT12. Ten rats were randomly assigned to SD during the light cycle and the remaining controls slept undisturbed. Treatment testing also occurred at ZT12, after which SD rats were allowed to sleep, and recovery testing followed at ZT14 or ZT16. Each testing session included three phases: acclimation (no objects), familiarization (identical objects), and recognition (novel/identical objects) with &lt; 4 minutes between phases. The recognition phase object discrimination ratio (DR) was analyzed using a mixed-effects ANOVA, with fixed effects of testing (baseline, treatment, recovery), group (control, SD), and their interaction. Secondary analyses assessed the effect of recovery-delay timing (ZT14, ZT16).

Results
There was a significant main effect of group (F[1,18]=7.64,p=0.013) and group by test interaction (F[2,36]=6.52,p=0.004). There were no differences between groups at baseline or recovery and no differences in recovery-delay. During the treatment test, SD rats were unable to recognize the novel object compared to controls (p&lt; 0.001), spending more time with the familiar object (p&lt; 0.001). Control rat performance worsened at recovery compared to treatment (p=0.033).

Conclusion
The serial NOR established baseline performance, which was associated with behavioral changes over time. SD significantly inhibited short-term recall, while controls presented stable performance from baseline to treatment testing, with significant performance deficits from treatment to recovery. This decrement may stem from habituation due to a short IPI and/or a time-of-day effect.

Support (if any)
WSU College of Medicine Department of Translational Medicine and Physiology
0066 Reactivating Remote Emotional Memory Before Sleep Impacts Dream Affect, but Not Dream Content
Authors: Frost Chadwick , Middleton Taya , Wamsley Erin 
Published: April 2024

Abstract

Introduction
Completing a learning task just before sleep often induces task-related dreams. This is thought to reflect the consolidation of recently formed memories in the sleeping brain. However, this literature has focused almost exclusively on how recent experiences newly introduced before sleep are incorporated into dreams. It is unknown whether and how remote memories may also be reactivated during sleep and incorporated into dreaming.

Methods
We aimed to experimentally trigger participants to dream about a remote emotional episodic memory. Just before a nap, participants (N = 34) completed the Autobiographical Emotional Memory Task (AEMT). In this task, participants were asked to recall and write about “the one situation that has made you the most angry you have been in your life”. In a control condition (within-subjects), participants instead wrote about designing a new college course. During the subsequent nap, participants were awoken up to four times to report their dream experiences. Following the nap, participants rated the extent to which they felt each dream was related to the earlier writing task, and rated the emotional valence of each dream.

Results
The AEMT elicited negative mood (pre-nap PANAS-negative score in AEMT vs. control condition: t(33)= 6.20, p&lt; 0.0001). Although participants rated some dreams as related to the pre-sleep writing task in both conditions, dreams were not significantly more related following the AEMT, as compared to the control condition (Wald test: χ2(1)=2.67, p=0.10). However, dream emotion was significantly more negative following the AEMT, relative to the control condition (Wald test: χ2(1)=5.15, p=0.02). This effect was strongest for the first dream reported.

Conclusion
Recalling a personal memory had no greater influence on dream content than writing about a neutral, memory-nrelated topic. At the same time, recalling a remote, emotional memory before sleep did affect the emotional valence of dreams. These data echo observations dating back to the 1960s suggesting that while transparent representations of presleep experience in dreams are rare, emotional stimuli do reliably influence dream affect. This might reflect emotional memory consolidation, or be a more general influence of pre-sleep mood on subsequent emotion during sleep.

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0067 The Effect of Aging on Emotional Memory Encoding and Consolidation over Sleep and Wake
Authors: Rodheim Katrina , Jones Bethany , Spencer Rebecca 
Published: April 2024

Abstract

Introduction
Sleep is essential for the consolidation of emotional memories. Young adults exhibit a bias towards consolidation of negative memories over sleep while older adults exhibit a bias towards consolidation of positive memories over sleep. As this parallels known biases in emotional memory encoding, it is unclear whether biases found after sleep are simply carried over from biases prior to sleep or if sleep amplifies emotional memory biases. Thus, the present study assessed emotional memory before and after intervals of sleep and wake to determine whether sleep biases the selectivity of emotional memory.

Methods
Healthy younger (N=52, 18-30 years; YA) and older adults (N=38, 50-80 years; OA) completed two conditions: a positive and negative emotional memory task. Emotional images were viewed followed by an immediate recognition assessment before overnight sleep (Sleep group; YA=29, OA=19) or before a day of wakefulness (Wake group; YA=23, OA=19). Delayed recognition was assessed approximately 12-hrs later. For the Sleep group, polysomnography was recorded. To assess differences in memory change (delayed minus immediate recognition) between condition (negative vs. positive), group (Sleep vs. Wake) and age (YA vs. OA), ANOVAs were conducted.

Results
There was a significant interaction between the effects of condition (positive vs. negative) and group (sleep vs. wake) (p=0.03) such that sleep (relative to wake) benefitted negative but not positive memories regardless of age. Investigating age groups separately, both younger (p=0.06) and older (p=0.06) adults tended to display this interaction. We next considered change in negative memory bias (negative – positive performance) between immediate and delayed recognition. There was a near-significant main effect of group (p=0.06), indicating that negative bias increased in the sleep compared to wake group.

Conclusion
These findings suggest sleep may impart a negative memory bias. This is consistent with our prior work in young adults but unexpected in older adults. This may suggest that, like young adults, healthy older adults preferentially consolidate negative over positive emotional memories during a night of sleep. Therefore, sleep-dependent emotional memory consolidation may be preserved even as sleep and memory decline with aging. Future analysis will examine associations between sleep architecture and emotional memory performance.

Support (if any)
NIH R01AG040133(PI: Spencer)
0068 The Impact of Transcutaneous Vagal Nerve Stimulation on Sleep-Dependent Emotional Memory
Authors: Perez Rene , Whitehurst Lauren , Subramoniam Anjana , Gilmore Gabriel 
Published: April 2024

Abstract

Introduction
The autonomic nervous system (ANS) supports memory, with peripheral activity, through the vagus nerve, enriching or impairing acquisition and consolidation, especially for emotional experiences. Sleep is critical for memory consolidation and has been implicated in affective regulation. Yet, the causal impact of the ANS during sleep for memory has not been rigorously assessed. The current project examined the impact of non-invasive vagal nerve stimulation during sleep on emotional memory consolidation

Methods
24 participants (Mean age = 22.82; 13 Male; 11 Female) completed two nights of polysomnographic recordings - one with 90-mins of active transcutaneous vagal nerve stimulation during NREM sleep and one with sham stimulation - counterbalanced across participants. Emotional memory was assessed via a picture recognition task. Sixty images were presented during a pre-sleep encoding session (30 negative and 30 neutral). Recognition memory (15 old/negative, 15 old/neutral, 15 new/negative and 15 new/neutral) was assessed twice, 30-mins after encoding (Test 1) and post-sleep (Test 2). Outcome metrics included d’ (sensitivity), c (bias criterion), and c’ (corrected sensitivity). Change scores (Test 2 -1) were calculated. Mixed-model repeated measures ANOVAs with self-reported biological sex as a between-subjects factor were used to assess the impact of stimulation (active vs sham) and valence conditions (negative vs neutral) on memory processing.

Results
For d’, a significant sexXstimulation interaction emerged, F(1,22)=6.66,p =0.017. Male participants performed better in the sham condition (p=0.035), but this effect was attenuated in the stimulation condition (p=0.236). Participants exercised a stricter criterion when receiving active vs. sham stimulation and were less likely to indicate that they remembered stimuli that they viewed during encoding at test (p=.051). Given this, we examined c’ to adjust for response bias. We found a significant effect of emotion (p=.025) and a marginal effect of stimulation condition (p=.058). Across sleep, participants were better at discriminating between previously encoded neutral images than negative images. Sleep-dependent discrimination performance also improved after active stimulation (c’=0.086) but declined under sham (c’=-0.018; p=.058).

Conclusion
These are the first data to suggest causal links between sleep-dependent autonomic activity and next-day memory processing. Analyses of polysomnographic sleep features linked to these outcomes are in progress.

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0071 Does Additional Training on a Motor Sequence Task Improve Sleep-Dependent Memory Consolidation for Older Adults?
Authors: Delvey Cassandra , Rodheim Katrina , Jones Bethany , Spencer Rebecca 
Published: April 2024

Abstract

Introduction
While sleep can improve memory performance, not all memory domains demonstrate this effect. Prior studies show that hippocampal engagement during encoding is necessary for subsequent sleep-dependent memory consolidation. However, motor sequence learning typically engages other areas and inconsistently demonstrates sleep-related gains, particularly among older adults. Hippocampal engagement via explicit sequence awareness and strong learning ability increases the possibility of sleep-related procedural memory gains. Therefore, we compared sleep-dependent memory consolidation on an explicit motor sequence task in older adults who received standard training to those who received additional training.

Methods
Healthy older adults (N=24; 67.7 ± 4.5 years; 71% female), assigned to a standard training group (n=12) or an over-training group (n=12), were trained on an explicit motor sequence learning task; standard training comprised 5 blocks of practice while over-training included 10. Performance was tested before (“immediate”) and after (“delayed”) a day spent awake and a night spent asleep (conditions separated by ~1 week, order counterbalanced). Skill learning was calculated by subtracting median reaction time during learned sequences from that of randomly-cued button presses. Change in skill learning from immediate to delayed test for the wake interval was contrasted with change across sleep, resulting in a sleep benefit score. Sleepiness was assessed using the Stanford Sleepiness Scale prior to each testing session. Polysomnography (32-channel, Brainvision) was recorded during the overnight sleep visit.

Results
A planned comparison of immediate test results, to check baseline differences resulting from training, showed that the over-training group was significantly faster than the standard training group (t(23)=4.796, p&lt;.001, d=1.18). Analysis of sleep benefit scores showed no significant benefit with standard training (t(11)=0.778, p=.453) or over-training (t(10)=1.342, p=.209), and over-training does not provide a significantly greater sleep benefit than standard training (t(23)=4.796, p=.590).

Conclusion
Our results replicate prior findings that standard training of a motor sequence task in older adults does not demonstrate sleep-dependent memory gains. Moreover, here we show that additional training does not improve the chances of demonstrating such gains, despite significantly improving initial performance. Because sleep spindles have been previously linked to motor sequence learning across sleep, future analysis will include polysomnography recordings.

Support (if any)
NIH R01 HL111695
0072 Preliminary Steps Towards an Overnight Intervention to Help Individuals with Age-related Memory Difficulties
Authors: Yamazaki Erika , Whitmore Nathan , Paller Ken 
Published: April 2024

Abstract

Introduction
Sleep supports memory consolidation and can prevent memories from being forgotten. Targeted Memory Reactivation (TMR) is an experimental technique that boosts the natural replay of recently acquired memories during sleep and can bias which memories are consolidated. TMR has been applied in many experiments by softly playing sounds associated with specific memories during slow-wave sleep, while not disrupting sleep. We developed a TMR algorithm that can be used in the home, with the future goal of decreasing forgetting for certain high-value information in seniors, particularly those with early-stage Alzheimer’s Disease.

Methods
In young healthy adults, we developed a learning procedure with 20 relationships and associated biographical information. We tested whether recall could be improved using TMR. On Day-1, participants learned relationships and facts about simulated family members (e.g., “Your youngest son is Clifford; Clifford is an architect”). After a short delay, they were tested on this information (e.g., “Your youngest son is___? Clifford’s occupation is___?”). On Day-2, participants learned interfering information about 10 simulated neighbors, followed by memory testing. While sleeping in their home for the next 3 nights, participants received auditory TMR cues during sleep using wearable sleep technology. Participants received either spoken questions about their simulated family (n=20, TMR group) or reversed sounds (n=20, control group). On Day-5, memory was tested again.

Results
Free recall of relationships and biographical information for the simulated family improved in the TMR group, whereas it declined in the control group (Day-5 vs. Day-1). Furthermore, recall confidence decreased less in the TMR group than in the control group (Day-5 vs. Day-1).

Conclusion
Results indicate that memory for specific information can be improved with overnight TMR sounds delivered in the home environment. The information was arbitrary person-specific knowledge that was recently acquired, but a parallel improvement may also be achievable in older individuals experiencing difficulty recalling high-value information subject to forgetting in their own lives. We are thus beginning studies in older individuals to test this possibility.

Support (if any)
Funding was provided by the National Institutes of Health (R01-NS112942 and T32-HL007909) and the National Science Foundation (BCS-2048681).
0076 Memory Consolidation During SWS of Implicit Visuospatial Memory Associated with Odor
Authors: Ahn Jungho , Takahashi Toshiharu 
Published: April 2024

Abstract

Introduction
Memory consolidation during sleep is more pronounced during SWS, but this effect depends on the form of learning (implicit or explicit). Also, it is considered that the piriform cortex, the primary olfactory cortex, replay and consolidates the olfactory stimuli perceived before sleep, as well as memories associated with the olfactory stimulus, during SWS. In this study, we investigated the consolidation of implicit visuospatial memory associated with olfactory stimuli during sleep in human subjects.

Methods
ROCF (Rey-Osterrieth Complex Figure) was used for the visuospatial memory task, and peppermint, liquid paraffin were used as experimental and control stimuli, respectively. Participants performed an implicit learning task in which they copied the ROCF while inhaling the experimental or control odor before nap(No instructions to memorize or test). After the learning, participants completed a baseline test in which they recalled the ROCF without inhaling the odor, and then took a 135-minute nap. After the nap, the ROCF recall test was repeated with inhaling experimental or control odor.

Results
Data from 28 of the 56 participants for whom SWS appeared were used in the statistical analysis. The analysis revealed that the slow-spindle PSD(Power Spectral Density) during SWS in the prefrontal cortex of the group that inhaled the experimental odor during ROCF learning was lower than that of the group in the control odor inhaled group. The results of linear regression analysis using prefrontal slow-spindle PSD as a moderator showed that when prefrontal slow-spindle PSD was lower than average, the memory performance (hit-rate change of ROCF) of the group that inhaled the experimental odor during ROCF learning was higher than that of the group that inhaled the control odor. This difference disappeared where the slow-spindle PSD exceeded the average.

Conclusion
Consolidation of odor associated implicit visuospatial memories during SWS was found to be associated with a decrease in prefrontal slow-spindle activity. Prefrontal slow-spindle activity during SWS is associated with the erasure of unstable memories, and olfactory cortex may suppress this activity to make unstable memories into long-lasting memories.

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0080 Selective Brain and Eye Responses to Auditory Stimuli During Phasic and Tonic REM Sleep
Authors: Ameen Mohamed , Topalidis Pavlos , Simor Peter , Schabus Manuel , Hoedlmoser Kerstin 
Published: April 2024

Abstract

Introduction
Rapid eye movement (REM) sleep is divided into phasic and tonic episodes based on the presence or absence of eye movements, respectively. Phasic REM, often linked with dreaming, is traditionally seen as a phase of brain isolation from the surroundings. On the contrary, during tonic REM periods, the brain is thought to maintain a stronger connection to the environment and a higher sensitivity to external stimuli. However, the processing of external information during these distinct REM microstates is not well-understood. Here, we aim to investigate sensory processing during REM microstates by analyzing brain and eye responses to different auditory stimuli.

Methods
We analyzed high-density electroencephalography (EEG) data from 17 healthy subjects over a full night's sleep. Auditory stimuli included the subjects' own name (SON) and two unfamiliar names (UNs), spoken by familiar (FV) and unfamiliar voices (UFV). REM sleep was categorized into one-second epochs of either phasic and tonic episodes based on rapid eye movement occurrence. Our analysis encompassed multivariate decoding, event-related and time-frequency analyses, examination of aperiodic EEG activity, and measuring the velocity of the evoked eye movement responses.

Results
Tonic REM showed more microarousals and a shallower EEG slope than phasic REM, suggesting increased external processing and more excitatory cortical activity. Further, auditory brain responses during tonic REM revealed stronger alpha (8-12 Hz) and beta (13-30 Hz) responses to responses to UFVs as compared to FVs. In contrast, during phasic REM, we observed stronger desynchronization in the delta (1-4 Hz) frequency range in response to UFVs as compared to FVs. No difference in brain responses to the different names was observed. However, eye responses to SONs were notably stronger than to UNs during phasic REM periods.

Conclusion
Our findings support existing theories that suggest a preference for unfamiliar stimuli processing during sleep. We extend previous findings by showing that such preference is perserved in REM sleep as well. We also found that eye movements in phasic REM can distinguish between sounds, indicating partial brain responsiveness to the environment during dreaming episodes. These results enhance our understanding of REM sleep's complex nature and the neural activities occurring during this intriguing sleep stage.

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0084 Differently Worded Questions Do Not Substantially Influence Subject Predictions of Performance
Authors: Hovland Sean , Hudson Amanda , Van Dongen Hans , Kurinec Courtney , Honn Kimberly 
Published: April 2024

Abstract

Introduction
Being able to accurately predict when one’s performance is likely to be impaired by sleep loss can help avoid costly errors. However, the literature is mixed on how accurately individuals are able to make such predictions. Subjective predictions of performance made during total sleep deprivation (TSD) are often only as accurate as judgments of subjective sleepiness, which are poorly correlated. We investigated whether the wording of a question about anticipated performance on a Psychomotor Vigilance Task (PVT) influences the ability to predict actual performance during TSD.

Methods
N=56 healthy adults (ages 25.9±5.3y, 32 females) were randomly assigned to 38h TSD in a 4-day/3-night laboratory study. The PVT and the Karolinska Sleepiness Scale (KSS) were administered approximately every 2-4h during scheduled wakefulness. We created four differently worded questions to elicit ratings of predicted performance on a scale from 1 (worse performance) to 9 (better performance). The questions asked about expected performance at the beginning or end of the PVT, expected duration of good performance, or expected time until impairment. Participants completed the KSS and answered one of the questions (randomly selected), and then performed the PVT. Using separate linear regressions with a fixed effect for rating and a random intercept over participants, we examined whether any of the questions, or the KSS ratings, were better able to predict PVT lapses (RT&gt;500ms). Results were compared using root mean square error (RMSE), a measure of absolute model fit.

Results
Using the predictive accuracy of the KSS as a reference (RMSE=4.71), the RMSE values for the questions ranged from 10.0% lower (RMSE=4.24), indicating slightly better accuracy for predicting subsequent PVT performance, to 13.0% higher (RMSE=5.32), indicating slightly worse accuracy for predicting subsequent PVT performance.

Conclusion
Our results suggest that the wording of a question about anticipated performance on the PVT influences its predictive utility, but with no more than 10% improvement over KSS-rated subjective sleepiness as a performance predictor, the predictive gain was not substantial. This puts into question whether self-predictions of performance, regardless of how they are framed, can be relied upon for assessments of readiness in operational settings.

Support (if any)
CDMRP W81XWH-16-1-0319