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Yuksel C, Denis D, Coleman J, Ren B, Oh A, Cox R, Morgan A, Sato E, Stickgold R. Both slow wave and rapid eye movement sleep contribute to emotional memory consolidation. Commun Biol 2025; 8:485. [PMID: 40123003 PMCID: PMC11930935 DOI: 10.1038/s42003-025-07868-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Accepted: 03/03/2025] [Indexed: 03/25/2025] Open
Abstract
Sleep supports memory consolidation, but the specific roles of different sleep stages in this process remain unclear. While rapid eye movement sleep (REM) has traditionally been linked to the processing of emotionally charged material, recent evidence suggests that slow wave sleep (SWS) also plays a role in strengthening emotional memories. Here, we use targeted memory reactivation (TMR) during REM and SWS in a daytime nap to directly examine which sleep stage is primarily involved in consolidating emotional declarative memories. Contrary to our hypothesis, reactivating emotional stimuli during REM impairs memory. Meanwhile, TMR benefit in SWS is strongly correlated with the product of time spent in REM and SWS. The emotional valence of cued items modulates both delta/theta power and sleep spindles. Furthermore, emotional memories benefit more from TMR than neutral ones. Our findings suggest that SWS and REM have complementary roles in consolidating emotional memories, with REM potentially involved in forgetting them. These results also expand on recent evidence highlighting a connection between sleep spindles and emotional processing.
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Affiliation(s)
- Cagri Yuksel
- Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA.
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
- Schizophrenia and Bipolar Disorder Program, McLean Hospital, Belmont, MA, USA.
| | - Dan Denis
- Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
- Department of Psychology, University of York, Heslington, York, UK
| | - James Coleman
- Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Boyu Ren
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
- Psychiatric Biostatistics Laboratory, McLean Hospital, Belmont, MA, USA
| | - Angela Oh
- Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Roy Cox
- Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
- Department of Sleep and Cognition, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Alexandra Morgan
- Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Erina Sato
- Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Robert Stickgold
- Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
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Mar'i J, Zhang R, Mircic S, Serbe-Kamp É, Meier M, Leonhardt A, Drews M, Del Grosso NA, Antony JW, Norman KA, Marzullo TC, Gage GJ. Study while you sleep: using targeted memory reactivation as an independent research project for undergraduates. ADVANCES IN PHYSIOLOGY EDUCATION 2025; 49:1-10. [PMID: 39446136 DOI: 10.1152/advan.00056.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 09/23/2024] [Accepted: 09/23/2024] [Indexed: 10/25/2024]
Abstract
Newly acquired information is stabilized into long-term memory through the process of consolidation. Memories are not static; rather, they are constantly updated via reactivation, and this reactivation occurs preferentially during slow-wave sleep (SWS; also referred to as N3 in humans). Here we present a scalable neuroscience research investigation of memory reactivation using low-cost electroencephalogram (EEG) recording hardware and open-source software for students and educators across the K-12 and higher education spectrum. The investigation uses a method called targeted memory reactivation (TMR), whereby auditory cues that were previously associated with learning are represented during sleep, triggering the recall of stored memories and (through this) strengthening these memories. We demonstrated the efficacy of this technique on seven healthy human subjects (19-35 years old, 3 females, four males). The subjects learned to play a spatial memory game on an app where they associated pictures (e.g., a clock) with locations on a grid while they listened to picture-appropriate sounds (e.g., "tic-toc"); next, they took a nap while undergoing EEG recordings. During SWS, half of the sounds from the game were replayed by the app, while half were substituted with nonlearned sounds. Subjects then played the memory game again after waking. Results showed that spatial recall was improved more for cued than uncued memories, demonstrating the benefits of memory replay during sleep and suggesting that one may intervene in this process to boost recall of specific memories. This research investigation takes advantage of the importance of sleep for memory consolidation and demonstrates improved memory performance by cueing sounds during SWS.NEW & NOTEWORTHY Why study when you could just sleep? We demonstrate how students can perform scalable research investigations to manipulate memory processing during sleep. It is a hands-on way to advance students' understanding of sleep-based memory consolidation and the corresponding neural mechanisms using open-source software and do-it-yourself EEG tools.
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Affiliation(s)
- Joud Mar'i
- Backyard Brains, Ann Arbor, Michigan, United States
- Mount Holyoke College, South Hadley, Massachusetts, United States
| | - Robert Zhang
- Princeton Neuroscience Institute, Princeton, New Jersey, United States
| | | | - Étienne Serbe-Kamp
- Backyard Brains, Ann Arbor, Michigan, United States
- Max Planck Institute of Neurobiology, Martinsried, Germany
- Ludwig Maximilian University (LMU), München, Germany
- Hirnkastl, München, Germany
| | - Matthias Meier
- Max Planck Institute of Neurobiology, Martinsried, Germany
- Hirnkastl, München, Germany
| | - Aljoscha Leonhardt
- Max Planck Institute of Neurobiology, Martinsried, Germany
- Hirnkastl, München, Germany
| | - Michael Drews
- Max Planck Institute of Neurobiology, Martinsried, Germany
- Hirnkastl, München, Germany
| | - Nicholas A Del Grosso
- Institute for Experimental Epileptology and Cognition Research, Uniklinikum Bonn, Bonn, Germany
| | - James W Antony
- Princeton Neuroscience Institute, Princeton, New Jersey, United States
| | - Kenneth A Norman
- Princeton Neuroscience Institute, Princeton, New Jersey, United States
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Sifuentes Ortega R, Peigneux P. Does targeted memory reactivation during slow-wave sleep and rapid eye movement sleep have differential effects on mnemonic discrimination and generalization? Sleep 2024; 47:zsae114. [PMID: 38766994 DOI: 10.1093/sleep/zsae114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 05/06/2024] [Indexed: 05/22/2024] Open
Abstract
Targeted memory reactivation (TMR), or the presentation of learning-related cues during sleep, has been shown to benefit memory consolidation for specific memory traces when applied during non-rapid eye movement (NREM) sleep. Prior studies suggest that TMR during rapid eye movement (REM) sleep may play a role in memory generalization processes, but evidence remains scarce. We tested the hypothesis that TMR exerts a differential effect on distinct mnemonic processes as a function of the sleep state (REM vs. NREM) in which TMR is delivered. Mnemonic discrimination and generalization of semantic categories were investigated using an adapted version of the Mnemonic Similarity Task, before and after sleep. Forty-eight participants encoded pictures from eight semantic categories, each associated with a sound. In the pre-sleep immediate test, they had to discriminate "old" (targets) from "similar" (lures) or "new" (foils) pictures. During sleep, half of the sounds were replayed in slow wave sleep (SWS) or REM sleep. Recognition, discrimination, and generalization memory indices were tested in the morning. These indices did not differ between SWS and REM TMR groups or reactivated and non-reactivated item categories. Additional results suggest a positive effect of TMR on performance for highly similar items mostly relying on mnemonic discrimination processes. During sleep, EEG activity after cue presentation increased in the delta-theta and sigma band in the SWS group, and in the beta band in the REM TMR group. These results do not support the hypothesis of differential processing of novel memory traces when TMR is administered in distinctive physiological sleep states.
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Affiliation(s)
- Rebeca Sifuentes Ortega
- UR2NF, Neuropsychology and Functional Neuroimaging Research Unit at CRCN affiliated at Center for Research in Cognition and Neurosciences and UNI - ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Philippe Peigneux
- UR2NF, Neuropsychology and Functional Neuroimaging Research Unit at CRCN affiliated at Center for Research in Cognition and Neurosciences and UNI - ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
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Temudo A, Albouy G. Using targeted memory reactivation as a tool to provide mechanistic insights into memory consolidation during sleep. Sleep 2024; 47:zsae163. [PMID: 39044535 DOI: 10.1093/sleep/zsae163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2024] [Indexed: 07/25/2024] Open
Affiliation(s)
- Ainsley Temudo
- Department of Health and Kinesiology, College of Health, University of Utah, Salt Lake City, UT, USA
| | - Geneviève Albouy
- Department of Health and Kinesiology, College of Health, University of Utah, Salt Lake City, UT, USA
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Zhao X, Chen PH, Chen J, Sun H. Manipulated overlapping reactivation of multiple memories promotes explicit gist abstraction. Neurobiol Learn Mem 2024; 213:107953. [PMID: 38950676 DOI: 10.1016/j.nlm.2024.107953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 05/19/2024] [Accepted: 06/14/2024] [Indexed: 07/03/2024]
Abstract
Sleep is considered to promote gist abstraction on the basis of spontaneous memory reactivation. As speculated in the theory of 'information overlap to abstract (iOtA)', 'overlap' between reactivated memories, beyond reactivation, is crucial to gist abstraction. Yet so far, empirical research has not tested this theory by manipulating the factor of 'overlap'. In the current study, 'overlap' itself was manipulated by targeted memory reactivation (TMR), through simultaneously reactivating multiple memories that either contain or do not contain spatially overlapped gist information, to investigate the effect of overlapping reactivation on gist abstraction. This study had a factorial design of 2 factors with 2 levels respectively (spatial overlap/no spatial overlap, TMR/no-TMR). Accordingly, 82 healthy college students (aged 19 ∼ 25, 57 females) were randomized into four groups. After learning 16 pictures, paired with 4 auditory cues (4 pictures - 1 cue) according to the grouping, participants were given a 90-minute nap opportunity. Then TMR cueing was conducted during N2 and slow wave sleep of the nap. Performance in memory task was used to measure gist abstraction. The results showed a significant main effect of TMR on both implicit and explicit gist abstraction, and a marginally significant interaction effect on explicit gist abstraction. Further analyses showed that explicit gist abstraction in the spatial overlap & TMR group was significantly better than in the control group. Moreover, explicit gist abstraction was positively correlated with spindle density. The current study thus indicates that TMR facilitates gist abstraction, and explicit gist abstraction may benefit more from overlapping reactivation.
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Affiliation(s)
- Xiaoxia Zhao
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, 51 HuayuanBei Road, Beijing 100191, China
| | - Po-Han Chen
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, 51 HuayuanBei Road, Beijing 100191, China
| | - Jie Chen
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, 51 HuayuanBei Road, Beijing 100191, China
| | - Hongqiang Sun
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, 51 HuayuanBei Road, Beijing 100191, China.
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Xia T, Chen D, Zeng S, Yao Z, Liu J, Qin S, Paller KA, Torres Platas SG, Antony JW, Hu X. Aversive memories can be weakened during human sleep via the reactivation of positive interfering memories. Proc Natl Acad Sci U S A 2024; 121:e2400678121. [PMID: 39052838 PMCID: PMC11295023 DOI: 10.1073/pnas.2400678121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 06/17/2024] [Indexed: 07/27/2024] Open
Abstract
Recollecting painful or traumatic experiences can be deeply troubling. Sleep may offer an opportunity to reduce such suffering. We developed a procedure to weaken older aversive memories by reactivating newer positive memories during sleep. Participants viewed 48 nonsense words each paired with a unique aversive image, followed by an overnight sleep. In the next evening, participants learned associations between half of the words and additional positive images, creating interference. During the following non-rapid-eye-movement sleep, auditory memory cues were unobtrusively delivered. Upon waking, presenting cues associated with both aversive and positive images during sleep, as opposed to not presenting cues, weakened aversive memory recall while increasing positive memory intrusions. Substantiating these memory benefits, computational modeling revealed that cueing facilitated evidence accumulation toward positive affect judgments. Moreover, cue-elicited theta brain rhythms during sleep predominantly predicted the recall of positive memories. A noninvasive sleep intervention can thus modify aversive recollection and affective responses.
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Affiliation(s)
- Tao Xia
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong Special Administrative Region999077, China
| | - Danni Chen
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong Special Administrative Region999077, China
| | - Shengzi Zeng
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong Special Administrative Region999077, China
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA02215
- Department of Psychiatry, Harvard Medical School, Boston, MA02215
| | - Ziqing Yao
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong Special Administrative Region999077, China
| | - Jing Liu
- Department of Applied Social Sciences, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region999077, China
| | - Shaozheng Qin
- State Key Laboratory of Cognitive Neuroscience and Learning and International Data Group McGovern Institute for Brain Research, Beijing Normal University, Beijing100875, China
| | - Ken A. Paller
- Cognitive Neuroscience Program and Department of Psychology, Northwestern University, Evanston, IL60208
| | - S. Gabriela Torres Platas
- Cognitive Neuroscience Program and Department of Psychology, Northwestern University, Evanston, IL60208
| | - James W. Antony
- Department of Psychology & Child Development, California Polytechnic State University, San Luis Obispo, CA93407
| | - Xiaoqing Hu
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong Special Administrative Region999077, China
- The University of Hong Kong-Shenzhen Institute of Research and Innovation, Shenzhen518057, China
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7
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Yao Z, Xia T, Wei J, Zhang Z, Lin X, Zhang D, Qin P, Ma Y, Hu X. Reactivating cue approached positive personality traits during sleep promotes positive self-referential processing. iScience 2024; 27:110341. [PMID: 39055925 PMCID: PMC11269284 DOI: 10.1016/j.isci.2024.110341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/16/2024] [Accepted: 06/19/2024] [Indexed: 07/28/2024] Open
Abstract
People preferentially endorse positive personality traits as more self-descriptive than negative ones, a positivity self-referential bias. Here, we investigated how to enhance positive self-referential processing, integrating wakeful cue-approach training task (CAT) and sleep-based targeted memory reactivation (TMR). In the CAT, participants gave speeded motor responses to cued positive personality traits. In a subsequent nap, we unobtrusively re-played half of the trained positive traits during slow-wave sleep (TMR). Upon awakening, CAT+TMR facilitated participants' speed in endorsing positive traits in immediate tests, and rendered participants endorse more positive traits as self-descriptive after one week. Notably, these enhancements were associated with the directionality of cue-related 1-4 Hz slow traveling waves (STW) that propagate across brain regions. Specifically, anterior-to-posterior backward STW was positively associated with these benefits, whereas forward STW showed negative associations. These findings demonstrate the potential benefits of integrated wakeful cue-approach training and sleep-based memory reactivation in strengthening positive self-referential processing.
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Affiliation(s)
- Ziqing Yao
- Department of Psychology and The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Tao Xia
- Department of Psychology and The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Jinwen Wei
- School of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China
| | - Zhiguo Zhang
- School of Computer Science and Technology, Harbin Institute of Technology, Shenzhen, China
- Peng Cheng Laboratory, Shenzhen 518055, China
| | - Xuanyi Lin
- Department of Psychology and The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
- Center for Sleep & Circadian Biology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208, USA
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208, USA
| | - Dandan Zhang
- Institute of Brain and Psychological Sciences, Sichuan Normal University, Chengdu, China
| | - Pengmin Qin
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education, School of Psychology, Center for Studies of Psychological Application, Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou, Guangdong 510631, China
| | - Yina Ma
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, Beijing Key Laboratory of Brain Imaging and Connectomics, Beijing Normal University, Beijing, China
- Chinese Institute for Brain Research, Beijing, China
| | - Xiaoqing Hu
- Department of Psychology and The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
- HKU, Shenzhen Institute of Research and Innovation, Shenzhen, China
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8
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Chen D, Xia T, Yao Z, Zhang L, Hu X. Modulating social learning-induced evaluation updating during human sleep. NPJ SCIENCE OF LEARNING 2024; 9:43. [PMID: 38971834 PMCID: PMC11227583 DOI: 10.1038/s41539-024-00255-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 06/13/2024] [Indexed: 07/08/2024]
Abstract
People often change their evaluations upon learning about their peers' evaluations, i.e., social learning. Given sleep's vital role in consolidating daytime experiences, sleep may facilitate social learning, thereby further changing people's evaluations. Combining a social learning task and the sleep-based targeted memory reactivation technique, we asked whether social learning-induced evaluation updating can be modulated during sleep. After participants had indicated their initial evaluation of snacks, they learned about their peers' evaluations while hearing the snacks' spoken names. During the post-learning non-rapid-eye-movement sleep, we re-played half of the snack names (i.e., cued snack) to reactivate the associated peers' evaluations. Upon waking up, we found that the social learning-induced evaluation updating further enlarged for both cued and uncued snacks. Examining sleep electroencephalogram (EEG) activity revealed that cue-elicited delta-theta EEG power and the overnight N2 sleep spindle density predicted post-sleep evaluation updating for cued but not for uncued snacks. These findings underscore the role of sleep-mediated memory reactivation and the associated neural activity in supporting social learning-induced evaluation updating.
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Affiliation(s)
- Danni Chen
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Tao Xia
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Ziqing Yao
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Lingqi Zhang
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Xiaoqing Hu
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China.
- HKU-Shenzhen Institute of Research and Innovation, Shenzhen, China.
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9
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Schreiner T, Griffiths BJ, Kutlu M, Vollmar C, Kaufmann E, Quach S, Remi J, Noachtar S, Staudigl T. Spindle-locked ripples mediate memory reactivation during human NREM sleep. Nat Commun 2024; 15:5249. [PMID: 38898100 PMCID: PMC11187142 DOI: 10.1038/s41467-024-49572-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 06/11/2024] [Indexed: 06/21/2024] Open
Abstract
Memory consolidation relies in part on the reactivation of previous experiences during sleep. The precise interplay of sleep-related oscillations (slow oscillations, spindles and ripples) is thought to coordinate the information flow between relevant brain areas, with ripples mediating memory reactivation. However, in humans empirical evidence for a role of ripples in memory reactivation is lacking. Here, we investigated the relevance of sleep oscillations and specifically ripples for memory reactivation during human sleep using targeted memory reactivation. Intracranial electrophysiology in epilepsy patients and scalp EEG in healthy participants revealed that elevated levels of slow oscillation - spindle activity coincided with the read-out of experimentally induced memory reactivation. Importantly, spindle-locked ripples recorded intracranially from the medial temporal lobe were found to be correlated with the identification of memory reactivation during non-rapid eye movement sleep. Our findings establish ripples as key-oscillation for sleep-related memory reactivation in humans and emphasize the importance of the coordinated interplay of the cardinal sleep oscillations.
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Affiliation(s)
- Thomas Schreiner
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Benjamin J Griffiths
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Merve Kutlu
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christian Vollmar
- Epilepsy Center, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Elisabeth Kaufmann
- Epilepsy Center, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stefanie Quach
- Department of Neurosurgery, University Hospital Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jan Remi
- Epilepsy Center, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Soheyl Noachtar
- Epilepsy Center, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Tobias Staudigl
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany.
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10
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Siefert EM, Uppuluri S, Mu J, Tandoc MC, Antony JW, Schapiro AC. Memory Reactivation during Sleep Does Not Act Holistically on Object Memory. J Neurosci 2024; 44:e0022242024. [PMID: 38604779 PMCID: PMC11170671 DOI: 10.1523/jneurosci.0022-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 03/12/2024] [Accepted: 03/20/2024] [Indexed: 04/13/2024] Open
Abstract
Memory reactivation during sleep is thought to facilitate memory consolidation. Most sleep reactivation research has examined how reactivation of specific facts, objects, and associations benefits their overall retention. However, our memories are not unitary, and not all features of a memory persist in tandem over time. Instead, our memories are transformed, with some features strengthened and others weakened. Does sleep reactivation drive memory transformation? We leveraged the Targeted Memory Reactivation technique in an object category learning paradigm to examine this question. Participants (20 female, 14 male) learned three categories of novel objects, where each object had unique, distinguishing features as well as features shared with other members of its category. We used a real-time EEG protocol to cue the reactivation of these objects during sleep at moments optimized to generate reactivation events. We found that reactivation improved memory for distinguishing features while worsening memory for shared features, suggesting a differentiation process. The results indicate that sleep reactivation does not act holistically on object memories, instead supporting a transformation where some features are enhanced over others.
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Affiliation(s)
- Elizabeth M Siefert
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Sindhuja Uppuluri
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Jianing Mu
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Marlie C Tandoc
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - James W Antony
- Department of Psychology and Child Development, California Polytechnic State University, San Luis Obispo, California 93407
| | - Anna C Schapiro
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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11
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Guttesen AÁV, Denis D, Gaskell MG, Cairney SA. Delineating memory reactivation in sleep with verbal and non-verbal retrieval cues. Cereb Cortex 2024; 34:bhae183. [PMID: 38745557 PMCID: PMC11094403 DOI: 10.1093/cercor/bhae183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/12/2024] [Accepted: 04/16/2024] [Indexed: 05/16/2024] Open
Abstract
Sleep supports memory consolidation via the reactivation of newly formed memory traces. One way to investigate memory reactivation in sleep is by exposing the sleeping brain to auditory retrieval cues; a paradigm known as targeted memory reactivation. To what extent the acoustic properties of memory cues influence the effectiveness of targeted memory reactivation, however, has received limited attention. We addressed this question by exploring how verbal and non-verbal memory cues affect oscillatory activity linked to memory reactivation in sleep. Fifty-one healthy male adults learned to associate visual stimuli with spoken words (verbal cues) and environmental sounds (non-verbal cues). Subsets of the verbal and non-verbal memory cues were then replayed during sleep. The voice of the verbal cues was either matched or mismatched to learning. Memory cues (relative to unheard control cues) prompted an increase in theta/alpha and spindle power, which have been heavily implicated in sleep-associated memory processing. Moreover, verbal memory cues were associated with a stronger increase in spindle power than non-verbal memory cues. There were no significant differences between the matched and mismatched verbal cues. Our findings suggest that verbal memory cues may be most effective for triggering memory reactivation in sleep, as indicated by an amplified spindle response.
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Affiliation(s)
- Anna á V Guttesen
- Department of Psychology, University of York, York YO10 5DD, United Kingdom
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, United Kingdom
| | - Dan Denis
- Department of Psychology, University of York, York YO10 5DD, United Kingdom
- York Biomedical Research Institute, University of York, York YO10 5DD, United Kingdom
| | - M Gareth Gaskell
- Department of Psychology, University of York, York YO10 5DD, United Kingdom
- York Biomedical Research Institute, University of York, York YO10 5DD, United Kingdom
| | - Scott A Cairney
- Department of Psychology, University of York, York YO10 5DD, United Kingdom
- York Biomedical Research Institute, University of York, York YO10 5DD, United Kingdom
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12
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Denis D, Payne JD. Targeted Memory Reactivation during Nonrapid Eye Movement Sleep Enhances Neutral, But Not Negative, Components of Memory. eNeuro 2024; 11:ENEURO.0285-23.2024. [PMID: 38769012 PMCID: PMC11140657 DOI: 10.1523/eneuro.0285-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 03/14/2024] [Accepted: 04/18/2024] [Indexed: 05/22/2024] Open
Abstract
Emotionally salient components of memory are preferentially remembered at the expense of accompanying neutral information. This emotional memory trade-off is enhanced over time, and possibly sleep, through a process of memory consolidation. Sleep is believed to benefit memory through a process of reactivation during nonrapid eye movement sleep (NREM). Here, targeted memory reactivation (TMR) was used to manipulate the reactivation of negative and neutral memories during NREM sleep. Thirty-one male and female participants encoded composite scenes containing either a negative or neutral object superimposed on an always neutral background. During NREM sleep, sounds associated with the scene object were replayed, and memory for object and background components was tested the following morning. We found that TMR during NREM sleep improved memory for neutral, but not negative scene objects. This effect was associated with sleep spindle activity, with a larger spindle response following TMR cues predicting TMR effectiveness for neutral items only. These findings therefore do not suggest a role of NREM memory reactivation in enhancing the emotional memory trade-off across a 12 h period but do align with growing evidence of spindle-mediated memory reactivation in service of neutral declarative memory.
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Affiliation(s)
- Dan Denis
- Department of Psychology, University of York, York YO10 5DD, United Kingdom,
| | - Jessica D Payne
- Department of Psychology, University of Notre Dame, Notre Dame, Indiana 46556
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13
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Paller KA. Recurring memory reactivation: The offline component of learning. Neuropsychologia 2024; 196:108840. [PMID: 38417546 PMCID: PMC10981210 DOI: 10.1016/j.neuropsychologia.2024.108840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/19/2024] [Accepted: 02/25/2024] [Indexed: 03/01/2024]
Abstract
One can be aware of the effort needed to memorize a new fact or to recall the name of a new acquaintance. Because of experiences like this, learning can seem to have only two components, encoding information and, after some delay, retrieving information. To the contrary, learning entails additional, intervening steps that sometimes are hidden from the learner. For firmly acquiring fact and event knowledge in particular, learners are generally not cognizant of the necessity of offline consolidation. The memories that persist to be available reliably at a later time, according to the present conceptualization, are the ones we repeatedly rehearse and integrate with other knowledge, whether we do this intentionally or unknowingly, awake or asleep. This article examines the notion that learning is not a function of waking brain activity alone. What happens in the brain while we sleep also impacts memory storage, and consequently is a critical component of learning. The idea that memories can change over time and become enduring has long been present in memory research and is foundational for the concept of memory consolidation. Nevertheless, the notion that memory consolidation happens during sleep faced much resistance before eventually being firmly established. Research is still needed to elucidate the operation and repercussions of repeated reactivation during sleep. Comprehensively understanding how offline memory reactivation contributes to learning is vital for both theoretical and practical considerations.
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Affiliation(s)
- Ken A Paller
- Northwestern University, Department of Psychology, Evanston, IL, 60208, USA.
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14
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Carbone J, Diekelmann S. An update on recent advances in targeted memory reactivation during sleep. NPJ SCIENCE OF LEARNING 2024; 9:31. [PMID: 38622159 PMCID: PMC11018807 DOI: 10.1038/s41539-024-00244-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 04/04/2024] [Indexed: 04/17/2024]
Abstract
Targeted Memory Reactivation (TMR) is a noninvasive tool to manipulate memory consolidation during sleep. TMR builds on the brain's natural processes of memory reactivation during sleep and aims to facilitate or bias these processes in a certain direction. The basis of this technique is the association of learning content with sensory cues, such as odors or sounds, that are presented during subsequent sleep to promote memory reactivation. Research on TMR has drastically increased over the last decade with rapid developments. The aim of the present review is to highlight the most recent advances of this research. We focus on effects of TMR on the strengthening of memories in the declarative, procedural and emotional memory domain as well as on ways in which TMR can be used to promote forgetting. We then discuss advanced technical approaches to determine the optimal timing of TMR within the ongoing oscillatory activity of the sleeping brain as well as the specificity of TMR for certain memory contents. We further highlight the specific effects of TMR during REM sleep and in influencing dream content. Finally, we discuss recent evidence for potential applications of TMR for mental health, educational purposes and in the home setting. In conclusion, the last years of research have provided substantial advances in TMR that can guide future endeavors in research and application.
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Affiliation(s)
- Julia Carbone
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, 72076, Tübingen, Germany
- Graduate Training Centre of Neuroscience, International Max Planck Research School, 72076, Tübingen, Germany
| | - Susanne Diekelmann
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, 72076, Tübingen, Germany.
- Department of Psychiatry and Psychotherapy, University Hospital Tübingen, 72070, Tübingen, Germany.
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15
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Staresina BP. Coupled sleep rhythms for memory consolidation. Trends Cogn Sci 2024; 28:339-351. [PMID: 38443198 DOI: 10.1016/j.tics.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 02/02/2024] [Accepted: 02/02/2024] [Indexed: 03/07/2024]
Abstract
How do passing moments turn into lasting memories? Sheltered from external tasks and distractions, sleep constitutes an optimal state for the brain to reprocess and consolidate previous experiences. Recent work suggests that consolidation is governed by the intricate interaction of slow oscillations (SOs), spindles, and ripples - electrophysiological sleep rhythms that orchestrate neuronal processing and communication within and across memory circuits. This review describes how sequential SO-spindle-ripple coupling provides a temporally and spatially fine-tuned mechanism to selectively strengthen target memories across hippocampal and cortical networks. Coupled sleep rhythms might be harnessed not only to enhance overnight memory retention, but also to combat memory decline associated with healthy ageing and neurodegenerative diseases.
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Affiliation(s)
- Bernhard P Staresina
- Department of Experimental Psychology, University of Oxford, Oxford, UK; Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK.
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16
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Schechtman E. When memories get complex, sleep comes to their rescue. Proc Natl Acad Sci U S A 2024; 121:e2402178121. [PMID: 38466857 PMCID: PMC10962965 DOI: 10.1073/pnas.2402178121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024] Open
Affiliation(s)
- Eitan Schechtman
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA92697
- Center for Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA92697
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17
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Denis D, Cairney SA. Neural reactivation during human sleep. Emerg Top Life Sci 2023; 7:487-498. [PMID: 38054531 PMCID: PMC10754334 DOI: 10.1042/etls20230109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/20/2023] [Accepted: 11/23/2023] [Indexed: 12/07/2023]
Abstract
Sleep promotes memory consolidation: the process by which newly acquired memories are stabilised, strengthened, and integrated into long-term storage. Pioneering research in rodents has revealed that memory reactivation in sleep is a primary mechanism underpinning sleep's beneficial effect on memory. In this review, we consider evidence for memory reactivation processes occurring in human sleep. Converging lines of research support the view that memory reactivation occurs during human sleep, and is functionally relevant for consolidation. Electrophysiology studies have shown that memory reactivation is tightly coupled to the cardinal neural oscillations of non-rapid eye movement sleep, namely slow oscillation-spindle events. In addition, functional imaging studies have found that brain regions recruited during learning become reactivated during post-learning sleep. In sum, the current evidence paints a strong case for a mechanistic role of neural reactivation in promoting memory consolidation during human sleep.
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Affiliation(s)
- Dan Denis
- Department of Psychology, University of York, York YO10 5DD, U.K
| | - Scott A. Cairney
- Department of Psychology, University of York, York YO10 5DD, U.K
- York Biomedical Research Institute, University of York, York YO10 5DD, U.K
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18
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Salgado-Puga K, Rothschild G. Exposure to sounds during sleep impairs hippocampal sharp wave ripples and memory consolidation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568283. [PMID: 38045371 PMCID: PMC10690295 DOI: 10.1101/2023.11.22.568283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Sleep is critical for the consolidation of recent experiences into long-term memories. As a key underlying neuronal mechanism, hippocampal sharp-wave ripples (SWRs) occurring during sleep define periods of hippocampal reactivation of recent experiences and have been causally linked with memory consolidation. Hippocampal SWR-dependent memory consolidation during sleep is often referred to as occurring during an "offline" state, dedicated to processing internally generated neural activity patterns rather than external stimuli. However, the brain is not fully disconnected from the environment during sleep. In particular, sounds heard during sleep are processed by a highly active auditory system which projects to brain regions in the medial temporal lobe, reflecting an anatomical pathway for sound modulation of hippocampal activity. While neural processing of salient sounds during sleep, such as those of a predator or an offspring, is evolutionarily adaptive, whether ongoing processing of environmental sounds during sleep interferes with SWR-dependent memory consolidation remains unknown. To address this question, we used a closed-loop system to deliver non-waking sound stimuli during or following SWRs in sleeping rats. We found that exposure to sounds during sleep suppressed the ripple power and reduced the rate of SWRs. Furthermore, sounds delivered during SWRs (On-SWR) suppressed ripple power significantly more than sounds delivered 2 seconds after SWRs (Off-SWR). Next, we tested the influence of sound presentation during sleep on memory consolidation. To this end, SWR-triggered sounds were applied during sleep sessions following learning of a conditioned place preference paradigm, in which rats learned a place-reward association. We found that On-SWR sound pairing during post-learning sleep induced a complete abolishment of memory retention 24 h following learning, while leaving memory retention immediately following sleep intact. In contrast, Off-SWR pairing weakened memory 24 h following learning as well as immediately following learning. Notably, On-SWR pairing induced a significantly larger impairment in memory 24 h after learning as compared to Off-SWR pairing. Together, these findings suggest that sounds heard during sleep suppress SWRs and memory consolidation, and that the magnitude of these effects are dependent on sound-SWR timing. These results suggest that exposure to environmental sounds during sleep may pose a risk for memory consolidation processes.
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19
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Antony JW, Schechtman E. Reap while you sleep: Consolidation of memories differs by how they were sown. Hippocampus 2023; 33:922-935. [PMID: 36973868 PMCID: PMC10429120 DOI: 10.1002/hipo.23526] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/26/2023] [Accepted: 03/01/2023] [Indexed: 03/29/2023]
Abstract
Newly formed memories are spontaneously reactivated during sleep, leading to their strengthening. This reactivation process can be manipulated by reinstating learning-related stimuli during sleep, a technique termed targeted memory reactivation. Numerous studies have found that delivering cues during sleep improves memory for simple associations, in which one cue reactivates one tested memory. However, real-life memories often live in rich, complex networks of associations. In this review, we will examine recent forays into investigating how targeted sleep reactivation affects memories within complex paradigms, in which one cue can reactivate multiple tested memories. A common theme across studies is that reactivation consequences do not merely depend on whether memories reside in complex arrangements, but on how memories interact with one another during acquisition. We therefore emphasize how intricate study design details that alter the nature of learning and/or participant intentions impact the outcomes of sleep reactivation. In some cases, complex networks of memories interact harmoniously to bring about mutual memory benefits; in other cases, memories interact antagonistically and produce selective impairments in retrieval. Ultimately, although this burgeoning area of research has yet to be systematically explored, results suggest that the fate of reactivated stimuli within complex arrangements depends on how they were learned.
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Affiliation(s)
- James W. Antony
- Department of Psychology and Child Development, California Polytechnic State University, San Luis Obispo, California, USA
| | - Eitan Schechtman
- Department of Neurobiology and Behavior, University of California, Irvine, California, USA
- Center for Neurobiology of Learning and Memory, University of California Irvine, Irvine, California, USA
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20
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Yuksel C, Denis D, Coleman J, Ren B, Oh A, Cox R, Morgan A, Sato E, Stickgold R. Emotional memories are enhanced when reactivated in slow wave sleep, but impaired when reactivated in REM. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.01.530661. [PMID: 36909630 PMCID: PMC10002730 DOI: 10.1101/2023.03.01.530661] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Sleep supports memory consolidation. However, it is not completely clear how different sleep stages contribute to this process. While rapid eye movement sleep (REM) has traditionally been implicated in the processing of emotionally charged material, recent studies indicate a role for slow wave sleep (SWS) in strengthening emotional memories. Here, to directly examine which sleep stage is primarily involved in emotional memory consolidation, we used targeted memory reactivation (TMR) in REM and SWS during a daytime nap. Contrary to our hypothesis, reactivation of emotional stimuli during REM led to impaired memory. Consistent with this, REM% was correlated with worse recall in the group that took a nap without TMR. Meanwhile, cueing benefit in SWS was strongly correlated with the product of times spent in REM and SWS (SWS-REM product), and reactivation significantly enhanced memory in those with high SWS-REM product. Surprisingly, SWS-REM product was associated with better memory for reactivated items and poorer memory for non-reactivated items, suggesting that sleep both preserved and eliminated emotional memories, depending on whether they were reactivated. Notably, the emotional valence of cued items modulated both sleep spindles and delta/theta power. Finally, we found that emotional memories benefited from TMR more than did neutral ones. Our results suggest that emotional memories decay during REM, unless they are reactivated during prior SWS. Furthermore, we show that active forgetting complements memory consolidation, and both take place across SWS and REM. In addition, our findings expand upon recent evidence indicating a link between sleep spindles and emotional processing.
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21
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Abdellahi MEA, Koopman ACM, Treder MS, Lewis PA. Targeted memory reactivation in human REM sleep elicits detectable reactivation. eLife 2023; 12:e84324. [PMID: 37350572 PMCID: PMC10425171 DOI: 10.7554/elife.84324] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 06/22/2023] [Indexed: 06/24/2023] Open
Abstract
It is now well established that memories can reactivate during non-rapid eye movement (non-REM) sleep, but the question of whether equivalent reactivation can be detected in rapid eye movement (REM) sleep is hotly debated. To examine this, we used a technique called targeted memory reactivation (TMR) in which sounds are paired with learned material in wake, and then re-presented in subsequent sleep, in this case REM, to trigger reactivation. We then used machine learning classifiers to identify reactivation of task-related motor imagery from wake in REM sleep. Interestingly, the strength of measured reactivation positively predicted overnight performance improvement. These findings provide the first evidence for memory reactivation in human REM sleep after TMR that is directly related to brain activity during wakeful task performance.
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Affiliation(s)
- Mahmoud EA Abdellahi
- School of Psychology, Cardiff University Brain Research Imaging Centre (CUBRIC)CardiffUnited Kingdom
| | - Anne CM Koopman
- School of Psychology, Cardiff University Brain Research Imaging Centre (CUBRIC)CardiffUnited Kingdom
| | - Matthias S Treder
- School of Computer Science and Informatics, Cardiff UniversityCardiffUnited Kingdom
| | - Penelope A Lewis
- School of Psychology, Cardiff University Brain Research Imaging Centre (CUBRIC)CardiffUnited Kingdom
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22
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Schechtman E, Heilberg J, Paller KA. Memory consolidation during sleep involves context reinstatement in humans. Cell Rep 2023; 42:112331. [PMID: 37014750 PMCID: PMC10545811 DOI: 10.1016/j.celrep.2023.112331] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/07/2023] [Accepted: 03/19/2023] [Indexed: 04/05/2023] Open
Abstract
New memories are not quarantined from each other when first encoded; rather, they are interlinked with memories that were encoded in temporal proximity or that share semantic features. By selectively biasing memory processing during sleep, here we test whether context influences sleep consolidation. Participants first formed 18 idiosyncratic narratives, each linking four objects together. Before sleep, they also memorized an on-screen position for each object. During sleep, 12 object-specific sounds were unobtrusively presented, thereby cuing the corresponding spatial memories and impacting spatial recall as a function of initial memory strength. As hypothesized, we find that recall for non-cued objects contextually linked with cued objects also changed. Post-cue electrophysiological responses suggest that activity in the sigma band supports context reinstatement and predicts context-related memory benefits. Concurrently, context-specific electrophysiological activity patterns emerge during sleep. We conclude that reactivation of individual memories during sleep evokes reinstatement of their context, thereby impacting consolidation of associated knowledge.
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Affiliation(s)
- Eitan Schechtman
- Department of Psychology, Northwestern University, Evanston, IL 60208, USA; Department of Neurobiology and Behavior, University of California at Irvine, Irvine, CA 92697, USA; Center for Neurobiology of Learning and Memory, University of California at Irvine, Irvine, CA 92697, USA.
| | - Julia Heilberg
- Department of Psychology, Northwestern University, Evanston, IL 60208, USA
| | - Ken A Paller
- Department of Psychology, Northwestern University, Evanston, IL 60208, USA
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23
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Xia T, Yao Z, Guo X, Liu J, Chen D, Liu Q, Paller KA, Hu X. Updating memories of unwanted emotions during human sleep. Curr Biol 2023; 33:309-320.e5. [PMID: 36584677 PMCID: PMC9979073 DOI: 10.1016/j.cub.2022.12.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/21/2022] [Accepted: 12/02/2022] [Indexed: 12/30/2022]
Abstract
Post-learning sleep contributes to memory consolidation. Yet it remains contentious whether sleep affords opportunities to modify or update emotional memories, particularly when people would prefer to forget those memories. Here, we attempted to update memories during sleep, using spoken positive words paired with cues to recent memories of aversive events. Affective updating using positive words during human non-rapid eye movement (NREM) sleep, compared with using neutral words instead, reduced negative affective judgments in post-sleep tests, suggesting that the recalled events were perceived as less aversive. Electroencephalogram (EEG) analyses showed that positive words modulated theta and spindle/sigma activity; specifically, to the extent that theta power was larger for the positive words than for the memory cues that followed, participants judged the memory cues less negatively. Moreover, to the extent that sigma power was larger for the positive words than for the memory cues that followed, participants forgot more episodic details about aversive events. Notably, when the onset of individual positive words coincided with the up-phase of slow oscillations (a state characterized by increased cortical excitability during NREM sleep), affective updating was more successful. In sum, we altered the affective content of memories via the strategic pairing of positive words and memory cues during sleep, linked with EEG theta power increases and the slow oscillation up-phase. These findings suggest novel possibilities for modifying unwanted memories during sleep, which would not require people to consciously confront memories that they prefer to avoid.
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Affiliation(s)
- Tao Xia
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Ziqing Yao
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Xue Guo
- Institute of Brain and Psychological Sciences, Sichuan Normal University, Chengdu 610068, China
| | - Jing Liu
- Department of Applied Social Sciences, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Danni Chen
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Qiang Liu
- Institute of Brain and Psychological Sciences, Sichuan Normal University, Chengdu 610068, China; Brain and Cognitive Neuroscience Research Center, Liaoning Normal University, Dalian 116029, China.
| | - Ken A Paller
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, IL 60208, USA
| | - Xiaoqing Hu
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China; HKU-Shenzhen Institute of Research and Innovation, Shenzhen 518057, China.
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24
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Whitmore NW, Harris JC, Kovach T, Paller KA. Improving memory via automated targeted memory reactivation during sleep. J Sleep Res 2022; 31:e13731. [PMID: 36129154 PMCID: PMC9649863 DOI: 10.1111/jsr.13731] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 08/26/2022] [Accepted: 08/31/2022] [Indexed: 12/30/2022]
Abstract
A widely accepted view in memory research is that previously acquired information can be reactivated during sleep, leading to persistent memory storage. Targeted memory reactivation (TMR) was developed as a technique whereby specific memories can be reactivated during sleep using a sensory stimulus linked to prior learning. As a research tool, TMR can improve memory, raising the possibility that it may be useful for cognitive enhancement and clinical therapy. A major challenge for the expanded use of TMR is that a skilled operator must manually control stimulation, which is impractical in many settings. To address this limitation, we developed the SleepStim system for automated TMR in the home. SleepStim includes a smartwatch to collect movement and heart-rate data, plus a smartphone to emit auditory cues. A machine-learning model identifies periods of deep sleep and triggers TMR sounds within these periods. We tested whether this system could replicate the spatial-memory benefit of in-laboratory TMR. Participants learned locations of objects on a grid, and then half of the object locations were reactivated during sleep over 3 nights. Recall was tested each morning. In an experiment with 61 participants, the TMR effect was not significant but varied systematically with stimulus intensity; low-intensity but not high-intensity stimuli produced memory benefits. In a second experiment with 24 participants, we limited stimulus intensity and found that TMR reliably improved spatial memory, consistent with effects observed in laboratory studies. We conclude that SleepStim can effectively accomplish automated TMR, and that avoiding sleep disruption is critical for TMR benefits.
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Affiliation(s)
- Nathan W. Whitmore
- Department of Psychology and Interdepartmental Neuroscience ProgramNorthwestern UniversityEvanstonIllinoisUSA
| | - Jasmine C. Harris
- Department of Psychology and Interdepartmental Neuroscience ProgramNorthwestern UniversityEvanstonIllinoisUSA
| | - Torin Kovach
- Department of Computer ScienceCarnegie Mellon UniversityPittsburghPennsylvaniaUSA
| | - Ken A. Paller
- Department of Psychology and Interdepartmental Neuroscience ProgramNorthwestern UniversityEvanstonIllinoisUSA
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25
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Electrophysiological markers of memory consolidation in the human brain when memories are reactivated during sleep. Proc Natl Acad Sci U S A 2022; 119:e2123430119. [PMID: 36279460 PMCID: PMC9636913 DOI: 10.1073/pnas.2123430119] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sleep contributes to memory consolidation, we presume, because memories are replayed during sleep. Understanding this aspect of consolidation can help with optimizing normal learning in many contexts and with treating memory disorders and other diseases. Here, we systematically manipulated sleep-based processing using targeted memory reactivation; brief sounds coupled with presleep learning were quietly presented again during sleep, producing 1) recall improvements for specific spatial memories associated with those sounds and 2) physiological responses in the sleep electroencephalogram. Neural activity in the hippocampus and adjacent medial temporal cortex was thus found in association with memory consolidation during sleep. These findings advance understanding of consolidation by linking beneficial memory changes during sleep to both memory reactivation and specific patterns of brain activity. Human accomplishments depend on learning, and effective learning depends on consolidation. Consolidation is the process whereby new memories are gradually stored in an enduring way in the brain so that they can be available when needed. For factual or event knowledge, consolidation is thought to progress during sleep as well as during waking states and to be mediated by interactions between hippocampal and neocortical networks. However, consolidation is difficult to observe directly but rather is inferred through behavioral observations. Here, we investigated overnight memory change by measuring electrical activity in and near the hippocampus. Electroencephalographic (EEG) recordings were made in five patients from electrodes implanted to determine whether a surgical treatment could relieve their seizure disorders. One night, while each patient slept in a hospital monitoring room, we recorded electrophysiological responses to 10 to 20 specific sounds that were presented very quietly, to avoid arousal. Half of the sounds had been associated with objects and their precise spatial locations that patients learned before sleep. After sleep, we found systematic improvements in spatial recall, replicating prior results. We assume that when the sounds were presented during sleep, they reactivated and strengthened corresponding spatial memories. Notably, the sounds also elicited oscillatory intracranial EEG activity, including increases in theta, sigma, and gamma EEG bands. Gamma responses, in particular, were consistently associated with the degree of improvement in spatial memory exhibited after sleep. We thus conclude that this electrophysiological activity in the hippocampus and adjacent medial temporal cortex reflects sleep-based enhancement of memory storage.
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26
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Ngo HVV, Staresina BP. Shaping overnight consolidation via slow-oscillation closed-loop targeted memory reactivation. Proc Natl Acad Sci U S A 2022; 119:e2123428119. [PMID: 36279449 PMCID: PMC9636934 DOI: 10.1073/pnas.2123428119] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 05/19/2022] [Indexed: 11/23/2022] Open
Abstract
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 approaches, controlling the timing of TMR cues with respect to ongoing slow-oscillation (SO) phases. Prior to sleep, participants learned associations between unique words and a set of repeating images (e.g., car) while hearing a prototypical image sound (e.g., engine starting). Memory performance on an immediate test vs. a test the next morning quantified overnight memory consolidation. Importantly, two image sounds were designated as TMR cues, with one cue delivered at SO UP states and the other delivered at SO DOWN states. A novel sound was used as a TMR control condition. Behavioral results revealed a significant reduction of overnight forgetting for words associated with UP-state TMR compared with words associated with DOWN-state TMR. Electrophysiological results showed that UP-state cueing led to enhancement of the ongoing UP state and was followed by greater spindle power than DOWN-state cueing. Moreover, UP-state (and not DOWN-state) cueing led to reinstatement of target image representations. Together, these results unveil the behavioral and mechanistic effects of delivering reminder cues at specific phases of endogenous sleep rhythms and mark an important step for the endeavor to experimentally modulate memories during sleep.
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Affiliation(s)
- Hong-Viet V. Ngo
- Department of Psychology, University of Lübeck, 23562 Lübeck, Germany
- Centre for Brain, Behavior and Metabolism, University of Lübeck, 23562 Lübeck, Germany
| | - Bernhard P. Staresina
- Department of Experimental Psychology, University of Oxford, Oxford OX2 6GG, United Kingdom
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford OX3 9DU, United Kingdom
- School of Psychology, University of Birmingham, Birmingham B15 2TT, United Kingdom
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27
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Joensen BH, Harrington MO, Berens SC, Cairney SA, Gaskell MG, Horner AJ. Targeted memory reactivation during sleep can induce forgetting of overlapping memories. LEARNING & MEMORY (COLD SPRING HARBOR, N.Y.) 2022; 29:401-411. [PMID: 36253007 PMCID: PMC9578373 DOI: 10.1101/lm.053594.122] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 08/26/2022] [Indexed: 11/24/2022]
Abstract
Memory reactivation during sleep can shape new memories into a long-term form. Reactivation of memories can be induced via the delivery of auditory cues during sleep. Although this targeted memory reactivation (TMR) approach can strengthen newly acquired memories, research has tended to focus on single associative memories. It is less clear how TMR affects retention for overlapping associative memories. This is critical, given that repeated retrieval of overlapping associations during wake can lead to forgetting, a phenomenon known as retrieval-induced forgetting (RIF). We asked whether a similar pattern of forgetting occurs when TMR is used to cue reactivation of overlapping pairwise associations during sleep. Participants learned overlapping pairs—learned separately, interleaved with other unrelated pairs. During sleep, we cued a subset of overlapping pairs using TMR. While TMR increased retention for the first encoded pairs, memory decreased for the second encoded pairs. This pattern of retention was only present for pairs not tested prior to sleep. The results suggest that TMR can lead to forgetting, an effect similar to RIF during wake. However, this effect did not extend to memories that had been strengthened via retrieval prior to sleep. We therefore provide evidence for a reactivation-induced forgetting effect during sleep.
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Affiliation(s)
- Bárður H Joensen
- Department of Psychology, University of York, York YO10 5DD, United Kingdom.,Institute of Cognitive Neuroscience, University College London, London WC1N 3AZ, United Kingdom.,Institute of Neurology, University College London, London WC1N 3BG, United Kingdom
| | | | - Sam C Berens
- School of Psychology, University of Sussex, Falmer BN1 9QH, United Kingdom
| | - Scott A Cairney
- Department of Psychology, University of York, York YO10 5DD, United Kingdom.,York Biomedical Research Institute, University of York, York YO10 5NG, United Kingdom
| | - M Gareth Gaskell
- Department of Psychology, University of York, York YO10 5DD, United Kingdom.,York Biomedical Research Institute, University of York, York YO10 5NG, United Kingdom
| | - Aidan J Horner
- Department of Psychology, University of York, York YO10 5DD, United Kingdom.,York Biomedical Research Institute, University of York, York YO10 5NG, United Kingdom
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28
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Pereira SIR, Tsimpanouli ME, Hutchison I, Schneider J, Anderson IM, McFarquhar M, Elliott R, Lewis PA. Cueing emotional memories during slow wave sleep modulates next-day activity in the orbitofrontal cortex and the amygdala. Neuroimage 2022; 253:119120. [PMID: 35331867 DOI: 10.1016/j.neuroimage.2022.119120] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 03/09/2022] [Accepted: 03/19/2022] [Indexed: 12/12/2022] Open
Abstract
Emotional memories are preferentially consolidated during sleep, through the process of memory reactivation. Targeted memory reactivation (TMR) has been shown to boost memory consolidation during sleep, but its neural correlates remain unclear, particularly for emotional memories. Here, we aimed to examine how TMR of emotional material during slow wave sleep (SWS) impacts upon neural processing during a subsequent arousal rating task. Participants were trained on a spatial memory task including negative and neutral pictures paired with semantically matching sounds. The picture-sound pairs were rated for emotional arousal before and after the spatial memory task. Then, half of the sounds from each emotional category (negative and neutral) were cued during SWS. The next day, participants were retested on both the arousal rating and the spatial memory task inside an MRI scanner, followed by another retest session a week later. Memory consolidation and arousal processing did not differ between cued and non-cued items of either emotional category. We found increased responses to emotional stimuli in the amygdala and orbitofrontal cortex (OFC), and a cueing versus emotion interaction in the OFC, whereby cueing neutral stimuli led to an increase in OFC activity, while cueing negative stimuli led to decreased OFC activation. Interestingly, the effect of cueing on amygdala activation was modulated by time spent in REM sleep. We conclude that SWS TMR impacts OFC activity, while REM sleep plays a role in mediating the effect of such cueing on amygdala.
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Affiliation(s)
| | | | - Isabel Hutchison
- School of Psychological Sciences, University of Manchester, Manchester, M13 9PL, UK
| | - Jules Schneider
- School of Psychology, Cardiff University Brain Research Imaging Centre, Cardiff, Wales, CF24 4HQ, UK; School of Psychological Sciences, University of Manchester, Manchester, M13 9PL, UK
| | - Ian M Anderson
- School of Psychological Sciences, University of Manchester, Manchester, M13 9PL, UK
| | - Martyn McFarquhar
- School of Psychological Sciences, University of Manchester, Manchester, M13 9PL, UK
| | - Rebecca Elliott
- School of Psychological Sciences, University of Manchester, Manchester, M13 9PL, UK
| | - Penelope A Lewis
- School of Psychology, Cardiff University Brain Research Imaging Centre, Cardiff, Wales, CF24 4HQ, UK; School of Psychological Sciences, University of Manchester, Manchester, M13 9PL, UK.
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29
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Carbone J, Bibián C, Reischl P, Born J, Forcato C, Diekelmann S. The effect of zolpidem on targeted memory reactivation during sleep. Learn Mem 2021; 28:307-318. [PMID: 34400532 PMCID: PMC8372567 DOI: 10.1101/lm.052787.120] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/07/2021] [Indexed: 01/05/2023]
Abstract
According to the active system consolidation theory, memory consolidation during sleep relies on the reactivation of newly encoded memory representations. This reactivation is orchestrated by the interplay of sleep slow oscillations, spindles, and theta, which are in turn modulated by certain neurotransmitters like GABA to enable long-lasting plastic changes in the memory store. Here we asked whether the GABAergic system and associated changes in sleep oscillations are functionally related to memory reactivation during sleep. We administered the GABAA agonist zolpidem (10 mg) in a double-blind placebo-controlled study. To specifically focus on the effects on memory reactivation during sleep, we experimentally induced such reactivations by targeted memory reactivation (TMR) with learning-associated reminder cues presented during post-learning slow-wave sleep (SWS). Zolpidem significantly enhanced memory performance with TMR during sleep compared with placebo. Zolpidem also increased the coupling of fast spindles and theta to slow oscillations, although overall the power of slow spindles and theta was reduced compared with placebo. In an uncorrected exploratory analysis, memory performance was associated with slow spindle responses to TMR in the zolpidem condition, whereas it was associated with fast spindle responses in placebo. These findings provide tentative first evidence that GABAergic activity may be functionally implicated in memory reactivation processes during sleep, possibly via its effects on slow oscillations, spindles and theta as well as their interplay.
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Affiliation(s)
- Julia Carbone
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, 72076 Tübingen, Germany
- Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tübingen, 72076 Tübingen, Germany
| | - Carlos Bibián
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, 72076 Tübingen, Germany
- Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tübingen, 72076 Tübingen, Germany
| | - Patrick Reischl
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, 72076 Tübingen, Germany
| | - Jan Born
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, 72076 Tübingen, Germany
- Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, 72076 Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, 72076 Tübingen, Germany
| | - Cecilia Forcato
- Laboratorio de Sueño y Memoria, Departamento de Ciencias de la Vida, Instituto Tecnológico de Buenos Aires (ITBA), Buenos Aires C1106ACD, Argentina
- Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires C1425FQB, Argentina
| | - Susanne Diekelmann
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, 72076 Tübingen, Germany
- Department of Psychiatry and Psychotherapy, University Hospital Tübingen, 72076 Tübingen, Germany
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30
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Witkowski S, Noh S, Lee V, Grimaldi D, Preston AR, Paller KA. Does memory reactivation during sleep support generalization at the cost of memory specifics? Neurobiol Learn Mem 2021; 182:107442. [PMID: 33892076 PMCID: PMC8187329 DOI: 10.1016/j.nlm.2021.107442] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 03/11/2021] [Accepted: 04/18/2021] [Indexed: 10/21/2022]
Abstract
Sleep is important for memory, but does it favor consolidation of specific details or extraction of generalized information? Both may occur together when memories are reactivated during sleep, or a loss of certain memory details may facilitate generalization. To examine these issues, we tested memory in participants who viewed landscape paintings by six artists. Paintings were cropped to show only a section of the scene. During a learning phase, each painting section was presented with the artist's name and with a nonverbal sound that had been uniquely associated with that artist. In a test of memory for specifics, participants were shown arrays of six painting sections, all by the same artist. Participants attempted to select the one that was seen in the learning phase. Generalization was tested by asking participants to view new paintings and, for each one, decide which of the six artists created it. After this testing, participants had a 90-minute sleep opportunity with polysomnographic monitoring. When slow-wave sleep was detected, three of the sound cues associated with the artists were repeatedly presented without waking the participants. After sleep, participants were again tested for memory specifics and generalization. Memory reactivation during sleep due to the sound cues led to a relative decline in accuracy on the specifics test, which could indicate the transition to a loss of detail that facilitates generalization, particularly details such as the borders. Generalization performance showed very little change after sleep and was unaffected by the sound cues. Although results tentatively implicate sleep in memory transformation, further research is needed to examine memory change across longer time periods.
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Affiliation(s)
- Sarah Witkowski
- Department of Psychology, Northwestern University, Evanston, IL, United States.
| | - Sharon Noh
- Department of Psychology, University of Texas at Austin, Austin, TX, United States; Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States
| | - Victoria Lee
- Department of Psychology, Northwestern University, Evanston, IL, United States
| | - Daniela Grimaldi
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL, United States
| | - Alison R Preston
- Department of Psychology, University of Texas at Austin, Austin, TX, United States; Center for Learning and Memory, University of Texas at Austin, Austin, TX, United States; Department of Neuroscience, University of Texas at Austin, Austin, TX, United States
| | - Ken A Paller
- Department of Psychology, Northwestern University, Evanston, IL, United States
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Schreiner T, Petzka M, Staudigl T, Staresina BP. Endogenous memory reactivation during sleep in humans is clocked by slow oscillation-spindle complexes. Nat Commun 2021; 12:3112. [PMID: 34035303 PMCID: PMC8149676 DOI: 10.1038/s41467-021-23520-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 05/04/2021] [Indexed: 02/04/2023] Open
Abstract
Sleep is thought to support memory consolidation via reactivation of prior experiences, with particular electrophysiological sleep signatures (slow oscillations (SOs) and sleep spindles) gating the information flow between relevant brain areas. However, empirical evidence for a role of endogenous memory reactivation (i.e., without experimentally delivered memory cues) for consolidation in humans is lacking. Here, we devised a paradigm in which participants acquired associative memories before taking a nap. Multivariate decoding was then used to capture endogenous memory reactivation during non-rapid eye movement (NREM) sleep in surface EEG recordings. Our results reveal reactivation of learning material during SO-spindle complexes, with the precision of SO-spindle coupling predicting reactivation strength. Critically, reactivation strength (i.e. classifier evidence in favor of the previously studied stimulus category) in turn predicts the level of consolidation across participants. These results elucidate the memory function of sleep in humans and emphasize the importance of SOs and spindles in clocking endogenous consolidation processes.
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Affiliation(s)
- Thomas Schreiner
- Department of Psychology, Ludwig-Maximilians-University, Munich, Germany
| | - Marit Petzka
- School of Psychology and Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Tobias Staudigl
- Department of Psychology, Ludwig-Maximilians-University, Munich, Germany
| | - Bernhard P Staresina
- School of Psychology and Centre for Human Brain Health, University of Birmingham, Birmingham, UK.
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