251
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Schlichting ML, Preston AR. Memory integration: neural mechanisms and implications for behavior. Curr Opin Behav Sci 2015; 1:1-8. [PMID: 25750931 DOI: 10.1016/j.cobeha.2014.07.005] [Citation(s) in RCA: 219] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Everyday behaviors require a high degree of flexibility, in which prior knowledge is applied to inform behavior in new situations. Such flexibility is thought to be supported in part by memory integration, a process whereby related memories become interconnected in the brain through recruitment of overlapping neuronal populations. Recent advances in cognitive and behavioral neuroscience highlight the importance of a hippocampal-medial prefrontal circuit in memory integration. Emerging evidence suggests that abstracted representations in medial prefrontal cortex guide reactivation of related memories during new encoding events, thus promoting hippocampal integration of related experiences. Moreover, recent work indicates that integrated memories are called upon during novel situations to facilitate a host of behaviors, from spatial navigation to imagination.
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Affiliation(s)
- Margaret L Schlichting
- Department of Psychology, The University of Texas at Austin, 1 University Station A8000, Austin, TX 78712, United States ; Center for Learning and Memory, The University of Texas at Austin, 1 University Station C7000, Austin, TX 78712, United States
| | - Alison R Preston
- Department of Psychology, The University of Texas at Austin, 1 University Station A8000, Austin, TX 78712, United States ; Center for Learning and Memory, The University of Texas at Austin, 1 University Station C7000, Austin, TX 78712, United States ; Department of Neuroscience, The University of Texas at Austin, 1 University Station C7000, Austin, TX 78712, United States
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252
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Friedrich M, Wilhelm I, Born J, Friederici AD. Generalization of word meanings during infant sleep. Nat Commun 2015; 6:6004. [PMID: 25633407 PMCID: PMC4316748 DOI: 10.1038/ncomms7004] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 12/01/2014] [Indexed: 02/06/2023] Open
Abstract
Sleep consolidates memory and promotes generalization in adults, but it is still unknown to what extent the rapidly growing infant memory benefits from sleep. Here we show that during sleep the infant brain reorganizes recent memories and creates semantic knowledge from individual episodic experiences. Infants aged between 9 and 16 months were given the opportunity to encode both objects as specific word meanings and categories as general word meanings. Event-related potentials indicate that, initially, infants acquire only the specific but not the general word meanings. About 1.5 h later, infants who napped during the retention period, but not infants who stayed awake, remember the specific word meanings and, moreover, successfully generalize words to novel category exemplars. Independently of age, the semantic generalization effect is correlated with sleep spindle activity during the nap, suggesting that sleep spindles are involved in infant sleep-dependent brain plasticity.
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Affiliation(s)
- Manuela Friedrich
- Department of Psychology, Humboldt University of Berlin, Rudower Chaussee 18, 12489 Berlin, Germany
- Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr. 1a, 04103 Leipzig, Germany
| | - Ines Wilhelm
- Child Development Center, University Children’s Hospital, Steinwiesstrasse 75, 8032 Zürich, Switzerland
- Institute of Medical Psychology and Behavioral Neurobiology and Center for Integrative Neuroscience, University of Tübingen, Otfried Müller-Str. 25, 72076 Tübingen, Germany
| | - Jan Born
- Institute of Medical Psychology and Behavioral Neurobiology and Center for Integrative Neuroscience, University of Tübingen, Otfried Müller-Str. 25, 72076 Tübingen, Germany
| | - Angela D. Friederici
- Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr. 1a, 04103 Leipzig, Germany
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253
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The role of rapid eye movement sleep for amygdala-related memory processing. Neurobiol Learn Mem 2015; 122:110-21. [PMID: 25638277 DOI: 10.1016/j.nlm.2015.01.008] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 12/19/2014] [Accepted: 01/19/2015] [Indexed: 01/01/2023]
Abstract
Over the years, rapid eye movement (REM) sleep has been associated with general memory consolidation, specific consolidation of perceptual, procedural, emotional and fear memories, brain maturation and preparation of waking consciousness. More recently, some of these associations (e.g., general and procedural memory consolidation) have been shown to be unlikely, while others (e.g., brain maturation and consciousness) remain inconclusive. In this review, we argue that both behavioral and neurophysiological evidence supports a role of REM sleep for amygdala-related memory processing: the amygdala-hippocampus-medial prefrontal cortex network involved in emotional processing, fear memory and valence consolidation shows strongest activity during REM sleep, in contrast to the hippocampus-medial prefrontal cortex only network which is more active during non-REM sleep. However, more research is needed to fully understand the mechanisms.
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254
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REM sleep and memory reorganization: Potential relevance for psychiatry and psychotherapy. Neurobiol Learn Mem 2015; 122:28-40. [PMID: 25602929 DOI: 10.1016/j.nlm.2015.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 12/28/2014] [Accepted: 01/05/2015] [Indexed: 12/18/2022]
Abstract
Sleep can foster the reorganization of memory, i.e. the emergence of new memory content that has not directly been encoded. Current neurophysiological and behavioral evidence can be integrated into a model positing that REM sleep particularly promotes the disintegration of existing schemas and their recombination in the form of associative thinking, creativity and the shaping of emotional memory. Particularly, REM sleep related dreaming might represent a mentation correlate for the reconfiguration of memory. In a final section, the potential relevance for psychiatry and psychotherapy is discussed.
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255
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Genzel L, Dresler M, Cornu M, Jäger E, Konrad B, Adamczyk M, Friess E, Steiger A, Czisch M, Goya-Maldonado R. Medial prefrontal-hippocampal connectivity and motor memory consolidation in depression and schizophrenia. Biol Psychiatry 2015; 77:177-86. [PMID: 25037555 DOI: 10.1016/j.biopsych.2014.06.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 06/01/2014] [Accepted: 06/02/2014] [Indexed: 12/24/2022]
Abstract
BACKGROUND Overnight memory consolidation is disturbed in both depression and schizophrenia, creating an ideal situation to investigate the mechanisms underlying sleep-related consolidation and to distinguish disease-specific processes from common elements in their pathophysiology. METHODS We investigated patients with depression and schizophrenia, as well as healthy control subjects (each n = 16), under a motor memory consolidation protocol with functional magnetic resonance imaging and polysomnography. RESULTS In a sequential finger-tapping task associated with the degree of hippocampal-prefrontal cortex functional connectivity during the task, significantly less overnight improvement was identified as a common deficit in both patient groups. A task-related overnight decrease in activation of the basal ganglia was observed in control subjects and schizophrenia patients; in contrast, patients with depression showed an increase. During the task, schizophrenia patients, in comparison with control subjects, additionally recruited adjacent cortical areas, which showed a decrease in functional magnetic resonance imaging activation overnight and were related to disease severity. Effective connectivity analyses revealed that the hippocampus was functionally connected to the motor task network, and the cerebellum decoupled from this network overnight. CONCLUSIONS While both patient groups showed similar deficits in consolidation associated with hippocampal-prefrontal cortex connectivity, other activity patterns more specific for disease pathology differed.
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Affiliation(s)
- Lisa Genzel
- Max Planck Institute of Psychiatry, Munich, Germany; Centre for Cognitive and Neural Systems, University of Edinburgh, Edinburgh, United Kingdom.
| | | | - Marion Cornu
- Max Planck Institute of Psychiatry, Munich, Germany
| | - Eugen Jäger
- Max Planck Institute of Psychiatry, Munich, Germany
| | - Boris Konrad
- Max Planck Institute of Psychiatry, Munich, Germany
| | | | | | - Axel Steiger
- Max Planck Institute of Psychiatry, Munich, Germany
| | | | - Roberto Goya-Maldonado
- Max Planck Institute of Psychiatry, Munich, Germany; Centre for Translational Research in Systems Neuroscience and Psychiatry, Department of Psychiatry and Psychotherapy, Georg August University, Göttingen, Germany
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256
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Hippocampal Sequences and the Cognitive Map. SPRINGER SERIES IN COMPUTATIONAL NEUROSCIENCE 2015. [DOI: 10.1007/978-1-4939-1969-7_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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257
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Holleman E, Battaglia FP. Memory Consolidation, Replay, and Cortico-Hippocampal Interactions. SPRINGER SERIES IN COMPUTATIONAL NEUROSCIENCE 2015. [DOI: 10.1007/978-1-4939-1969-7_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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258
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The reorganisation of memory during sleep. Sleep Med Rev 2014; 18:531-41. [DOI: 10.1016/j.smrv.2014.03.005] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 03/10/2014] [Accepted: 03/10/2014] [Indexed: 11/21/2022]
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259
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Batterink LJ, Oudiette D, Reber PJ, Paller KA. Sleep facilitates learning a new linguistic rule. Neuropsychologia 2014; 65:169-79. [PMID: 25447376 PMCID: PMC4259849 DOI: 10.1016/j.neuropsychologia.2014.10.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/16/2014] [Accepted: 10/19/2014] [Indexed: 11/28/2022]
Abstract
Natural languages contain countless regularities. Extraction of these patterns is an essential component of language acquisition. Here we examined the hypothesis that memory processing during sleep contributes to this learning. We exposed participants to a hidden linguistic rule by presenting a large number of two-word phrases, each including a noun preceded by one of four novel words that functioned as an article (e.g., gi rhino). These novel words (ul, gi, ro and ne) were presented as obeying an explicit rule: two words signified that the noun referent was relatively near, and two that it was relatively far. Undisclosed to participants was the fact that the novel articles also predicted noun animacy, with two of the articles preceding animate referents and the other two preceding inanimate referents. Rule acquisition was tested implicitly using a task in which participants responded to each phrase according to whether the noun was animate or inanimate. Learning of the hidden rule was evident in slower responses to phrases that violated the rule. Responses were delayed regardless of whether rule-knowledge was consciously accessible. Brain potentials provided additional confirmation of implicit and explicit rule-knowledge. An afternoon nap was interposed between two 20-min learning sessions. Participants who obtained greater amounts of both slow-wave and rapid-eye-movement sleep showed increased sensitivity to the hidden linguistic rule in the second session. We conclude that during sleep, reactivation of linguistic information linked with the rule was instrumental for stabilizing learning. The combination of slow-wave and rapid-eye-movement sleep may synergistically facilitate the abstraction of complex patterns in linguistic input.
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Affiliation(s)
- Laura J Batterink
- Northwestern University, Department of Psychology, 2029 Sheridan Road, Evanston, IL 60208, United States.
| | - Delphine Oudiette
- Northwestern University, Department of Psychology, 2029 Sheridan Road, Evanston, IL 60208, United States
| | - Paul J Reber
- Northwestern University, Department of Psychology, 2029 Sheridan Road, Evanston, IL 60208, United States
| | - Ken A Paller
- Northwestern University, Department of Psychology, 2029 Sheridan Road, Evanston, IL 60208, United States
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260
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Chatburn A, Lushington K, Kohler MJ. Complex associative memory processing and sleep: A systematic review and meta-analysis of behavioural evidence and underlying EEG mechanisms. Neurosci Biobehav Rev 2014; 47:646-55. [DOI: 10.1016/j.neubiorev.2014.10.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 09/26/2014] [Accepted: 10/20/2014] [Indexed: 10/24/2022]
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261
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Abstract
Converging evidence suggests that dreaming is influenced by the consolidation of memory during sleep. Following encoding, recently formed memory traces are gradually stabilized and reorganized into a more permanent form of long-term storage. Sleep provides an optimal neurophysiological state to facilitate this process, allowing memory networks to be repeatedly reactivated in the absence of new sensory input. The process of memory reactivation and consolidation in the sleeping brain appears to influence conscious experience during sleep, contributing to dream content recalled on awakening. This article outlines several lines of evidence in support of this hypothesis, and responds to some common objections.
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Affiliation(s)
- Erin J Wamsley
- Department of Psychiatry, Harvard Medical School, Boston, MA, 02115, USA,
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262
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Impaired off-line motor skills consolidation in young primary insomniacs. Neurobiol Learn Mem 2014; 114:141-7. [DOI: 10.1016/j.nlm.2014.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 06/04/2014] [Accepted: 06/11/2014] [Indexed: 11/22/2022]
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263
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REM sleep, hippocampus, and memory processing: insights from functional neuroimaging studies. Behav Brain Sci 2014; 36:629-30; discussion 634-59. [PMID: 24304771 DOI: 10.1017/s0140525x13001441] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Neuroimaging studies show that episodic memory encoding is associated with increased activity in hippocampus and lateral prefrontal cortex; however, the latter structure shows decreased activity in rapid eye movement (REM) sleep. Together with few episodic memory traces in REM sleep, and REM sleep deprivation affecting hippocampus-independent emotional processes, this argues for generic information processing in REM sleep rather than linking episodic memory traces.
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264
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Sweegers CCG, Talamini LM. Generalization from episodic memories across time: a route for semantic knowledge acquisition. Cortex 2014; 59:49-61. [PMID: 25129237 DOI: 10.1016/j.cortex.2014.07.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/21/2014] [Accepted: 07/12/2014] [Indexed: 11/18/2022]
Abstract
The storage of input regularities, at all levels of processing complexity, is a fundamental property of the nervous system. At high levels of complexity, this may involve the extraction of associative regularities between higher order entities such as objects, concepts and environments across events that are separated in space and time. We propose that such a mechanism provides an important route towards the formation of higher order semantic knowledge. The present study assessed whether subjects were able to extract complex regularities from multiple associative memories and whether they could generalize this regularity knowledge to new items. We used a memory task in which subjects were required to learn face-location associations, but in which certain facial features were predictive of locations. We assessed generalization, as well as memory for arbitrary stimulus components, over a 4-h post-encoding consolidation period containing wakefulness or sleep. We also assessed the stability of regularity knowledge across a period of several weeks thereafter. We found that subjects were able to detect the regularity structure and use it in a generalization task. Interestingly, the performance on this task increased across the 4hr post-learning period. However, no differential effects of cerebral sleep and wake states during this interval were observed. Furthermore, it was found that regularity extraction hampered the storage of arbitrary facial features, resulting in an impoverished memory trace. Finally, across a period of several weeks, memory for the regularity structure appeared very robust whereas memory for arbitrary associations showed steep forgetting. The current findings improve our understanding of how regularities across memories impact memory (trans)formation.
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Affiliation(s)
| | - Lucia M Talamini
- Department of Psychology, University of Amsterdam, The Netherlands
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265
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Interplay between short- and long-term plasticity in cell-assembly formation. PLoS One 2014; 9:e101535. [PMID: 25007209 PMCID: PMC4090127 DOI: 10.1371/journal.pone.0101535] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 06/08/2014] [Indexed: 11/19/2022] Open
Abstract
Various hippocampal and neocortical synapses of mammalian brain show both short-term plasticity and long-term plasticity, which are considered to underlie learning and memory by the brain. According to Hebb’s postulate, synaptic plasticity encodes memory traces of past experiences into cell assemblies in cortical circuits. However, it remains unclear how the various forms of long-term and short-term synaptic plasticity cooperatively create and reorganize such cell assemblies. Here, we investigate the mechanism in which the three forms of synaptic plasticity known in cortical circuits, i.e., spike-timing-dependent plasticity (STDP), short-term depression (STD) and homeostatic plasticity, cooperatively generate, retain and reorganize cell assemblies in a recurrent neuronal network model. We show that multiple cell assemblies generated by external stimuli can survive noisy spontaneous network activity for an adequate range of the strength of STD. Furthermore, our model predicts that a symmetric temporal window of STDP, such as observed in dopaminergic modulations on hippocampal neurons, is crucial for the retention and integration of multiple cell assemblies. These results may have implications for the understanding of cortical memory processes.
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266
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O'Donnell C, Sejnowski TJ. Selective memory generalization by spatial patterning of protein synthesis. Neuron 2014; 82:398-412. [PMID: 24742462 DOI: 10.1016/j.neuron.2014.02.028] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2014] [Indexed: 02/07/2023]
Abstract
Protein synthesis is crucial for both persistent synaptic plasticity and long-term memory. De novo protein expression can be restricted to specific neurons within a population, and to specific dendrites within a single neuron. Despite its ubiquity, the functional benefits of spatial protein regulation for learning are unknown. We used computational modeling to study this problem. We found that spatially patterned protein synthesis can enable selective consolidation of some memories but forgetting of others, even for simultaneous events that are represented by the same neural population. Key factors regulating selectivity include the functional clustering of synapses on dendrites, and the sparsity and overlap of neural activity patterns at the circuit level. Based on these findings, we proposed a two-step model for selective memory generalization during REM and slow-wave sleep. The pattern-matching framework we propose may be broadly applicable to spatial protein signaling throughout cortex and hippocampus.
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Affiliation(s)
- Cian O'Donnell
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
| | - Terrence J Sejnowski
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093, USA
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267
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Patterns across multiple memories are identified over time. Nat Neurosci 2014; 17:981-6. [PMID: 24880213 DOI: 10.1038/nn.3736] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 05/08/2014] [Indexed: 01/10/2023]
Abstract
Memories are not static but continue to be processed after encoding. This is thought to allow the integration of related episodes via the identification of patterns. Although this idea lies at the heart of contemporary theories of systems consolidation, it has yet to be demonstrated experimentally. Using a modified water-maze paradigm in which platforms are drawn stochastically from a spatial distribution, we found that mice were better at matching platform distributions 30 d compared to 1 d after training. Post-training time-dependent improvements in pattern matching were associated with increased sensitivity to new platforms that conflicted with the pattern. Increased sensitivity to pattern conflict was reduced by pharmacogenetic inhibition of the medial prefrontal cortex (mPFC). These results indicate that pattern identification occurs over time, which can lead to conflicts between new information and existing knowledge that must be resolved, in part, by computations carried out in the mPFC.
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268
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Borquez M, Born J, Navarro V, Betancourt R, Inostroza M. Sleep enhances inhibitory behavioral control in discrimination learning in rats. Exp Brain Res 2014; 232:1469-77. [PMID: 24322821 PMCID: PMC4010722 DOI: 10.1007/s00221-013-3797-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 11/25/2013] [Indexed: 11/12/2022]
Abstract
Sleep supports the consolidation of memory, and it has been proposed that this enhancing effect of sleep pertains in particular to memories which are encoded under control of prefrontal-hippocampal circuitry into an episodic memory system. Furthermore, repeated reactivation and transformation of such memories during sleep are thought to promote the de-contextualization of these memories. Here, we aimed to establish a behavioral model for the study of such sleep-dependent system consolidation in rats, using a go/nogo conditional discrimination learning task known to essentially depend on prefrontal-hippocampal function. Different groups of rats were trained to criterion on this task and, then, subjected to 80-min retention intervals filled with spontaneous morning sleep, sleep deprivation, or spontaneous evening wakefulness. In a subsequent test phase, the speed of relearning of the discrimination task was examined as indicator of memory, whereby rats were either tested in the same context as during training or in a different context. Sleep promoted relearning of the conditional discrimination task, and this effect was similar for testing memory in the same or different context (p < 0.001). Independent of sleep and wakefulness during the retention interval, animals showed faster relearning when tested in the same context as during learning, compared with testing in a different context (p < 0.001). The benefitting effect of sleep on discrimination learning was primarily due to an enhancing effect on response suppression during the nogo stimulus. We infer from these results that sleep enhances memory for inhibitory behavioral control in a generalized context-independent manner and thereby might eventually also contribute to the abstraction of schema-like representations.
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Affiliation(s)
| | - Jan Born
- Center for Integrative Neuroscience, Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Otfried-Müller-Strasse 25, 72076 Tübingen, Germany
| | - Victor Navarro
- Departamento de Psicología, Universidad de Chile, Santiago, Chile
| | | | - Marion Inostroza
- Departamento de Psicología, Universidad de Chile, Santiago, Chile
- Center for Integrative Neuroscience, Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Otfried-Müller-Strasse 25, 72076 Tübingen, Germany
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269
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Abstract
Recent studies on the hippocampus and the prefrontal cortex have considerably advanced our understanding of the distinct roles of these brain areas in the encoding and retrieval of memories, and of how they interact in the prolonged process by which new memories are consolidated into our permanent storehouse of knowledge. These studies have led to a new model of how the hippocampus forms and replays memories and how the prefrontal cortex engages representations of the meaningful contexts in which related memories occur, as well as how these areas interact during memory retrieval. Furthermore, they have provided new insights into how interactions between the hippocampus and prefrontal cortex support the assimilation of new memories into pre-existing networks of knowledge, called schemas, and how schemas are modified in this process as the foundation of memory consolidation.
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Affiliation(s)
- Alison R Preston
- Center for Learning and Memory, 1 University Station C7000, University of Texas at Austin, Austin, TX 78712-0805, USA
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270
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Takeuchi M, Furuta H, Sumiyoshi T, Suzuki M, Ochiai Y, Hosokawa M, Matsui M, Kurachi M. Does sleep improve memory organization? Front Behav Neurosci 2014; 8:65. [PMID: 24782726 PMCID: PMC3986543 DOI: 10.3389/fnbeh.2014.00065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 02/15/2014] [Indexed: 11/13/2022] Open
Abstract
Sleep can integrate information into existing memory networks, look for common patterns and distil overarching rules, or simply stabilize and strengthen the memory exactly as it was learned. Recent research has shown that sleep facilitates abstraction of gist information as well as integration across multiple memories, insight into hidden solutions, and even the ability to make creative connections between distantly related ideas and concepts. To investigate the effect of sleep on memory organization, 35 normal volunteers were randomly assigned either to the sleep (n = 17) or wake group (n = 18). The sleep subjects performed the Japanese Verbal Learning Test (JVLT), a measure of learning and memory, three times in the evening, and slept. On the following morning (9 h later), they were asked to recall the words on the list. The wake subjects took the same test in the morning, and were asked to recall the words in the same time interval as in the sleep group. The semantic clustering ratio (SCR), divided by the total number of words recalled, was used as an index of memory organization. Our main interest was whether the sleep subjects elicit a greater increase in this measure from the third to the fourth assessments. Time × Group interaction effect on SCR was not significant between the sleep group and wake group as a whole. Meanwhile, the change in the SCR between the third and fourth trials was negatively correlated with duration of nocturnal waking in the sleep group, but not other sleep indices. Based on this observation, further analysis was conducted for subjects in the sleep group who awoke nocturnally for <60 min for comparison with the wake group. A significant Time × Group interaction was noted; these "good-sleepers" showed a significantly greater improvement in the memory index compared with the wake subjects. These results provide the first suggestion that sleep may enhance memory organization, which requires further study.
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Affiliation(s)
- Masashi Takeuchi
- Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Sciences , Toyama , Japan ; Kamiichi General Hospital , Kamiichi-machi , Japan
| | - Hisakazu Furuta
- Sleep Disorders Center, Hokuriku National Hospital , Nanto-shi , Japan
| | - Tomiki Sumiyoshi
- Department of Clinical Research Promotion, National Center Hospital, National Center of Neurology and Psychiatry , Tokyo , Japan
| | - Michio Suzuki
- Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Sciences , Toyama , Japan
| | - Yoko Ochiai
- Sleep Disorders Center, Hokuriku National Hospital , Nanto-shi , Japan
| | - Munehito Hosokawa
- Sleep Disorders Center, Hokuriku National Hospital , Nanto-shi , Japan
| | - Mie Matsui
- Department of Psychology, University of Toyama Graduate School of Medicine and Pharmaceutical Sciences , Toyama , Japan
| | - Masayoshi Kurachi
- Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Sciences , Toyama , Japan
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271
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Abstract
Sleep is essential for effective cognitive functioning. Loosing even a few hours of sleep can have detrimental effects on a wide variety of cognitive processes such as attention, language, reasoning, decision making, learning and memory. While sleep is necessary to ensure normal healthy cognitive functioning, it can also enhance performance beyond the boundaries of the normal condition. This article discusses the enhancing potential of sleep, mainly focusing on the domain of learning and memory. Sleep is known to facilitate the consolidation of memories learned before sleep as well as the acquisition of new memories to be learned after sleep. According to a widely held model this beneficial effect of sleep relies on the neuronal reactivation of memories during sleep that is associated with sleep-specific brain oscillations (slow oscillations, spindles, ripples) as well as a characteristic neurotransmitter milieu. Recent research indicates that memory processing during sleep can be boosted by (i) cueing memory reactivation during sleep; (ii) stimulating sleep-specific brain oscillations; and (iii) targeting specific neurotransmitter systems pharmacologically. Olfactory and auditory cues can be used, for example, to increase reactivation of associated memories during post-learning sleep. Intensifying neocortical slow oscillations (the hallmark of slow wave sleep (SWS)) by electrical or auditory stimulation and modulating specific neurotransmitters such as noradrenaline and glutamate likewise facilitates memory processing during sleep. With this evidence in mind, this article concludes by discussing different methodological caveats and ethical issues that should be considered when thinking about using sleep for cognitive enhancement in everyday applications.
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Affiliation(s)
- Susanne Diekelmann
- Institute of Medical Psychology and Behavioral Neurobiology, University Tübingen Tübingen, Germany
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272
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Song S, Cohen LG. Practice and sleep form different aspects of skill. Nat Commun 2014; 5:3407. [PMID: 24647040 DOI: 10.1038/ncomms4407] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 02/06/2014] [Indexed: 11/09/2022] Open
Abstract
Performance for skills such as a sequence of finger movements improves during sleep. This has widely been interpreted as evidence for a role of sleep in strengthening skill learning. Here we propose a different interpretation. We propose that practice and sleep form different aspects of skill. To show this, we train 80 subjects on a sequence of key-presses and test at different time points to determine the amount of skill stored in transition (that is, pressing '2' after '3' in '4-3-2-1') and ordinal (that is, pressing '2' in the third ordinal position in '4-3-2-1') forms. We find transition representations improve with practice and ordinal representations improve during sleep. Further, whether subjects can verbalize the trained sequence affects the formation of ordinal but not transition representations. Verbal knowledge itself does not increase over sleep. Thus, sleep encodes different representations of memory than practice, and may mediate conversion of memories between declarative and procedural forms.
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Affiliation(s)
- Sunbin Song
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Leonardo G Cohen
- Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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273
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Weber FD, Wang JY, Born J, Inostroza M. Sleep benefits in parallel implicit and explicit measures of episodic memory. Learn Mem 2014; 21:190-8. [PMID: 24634354 PMCID: PMC3966543 DOI: 10.1101/lm.033530.113] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Research in rats using preferences during exploration as a measure of memory has indicated that sleep is important for the consolidation of episodic-like memory, i.e., memory for an event bound into specific spatio-temporal context. How these findings relate to human episodic memory is unclear. We used spontaneous preferences during visual exploration and verbal recall as, respectively, implicit and explicit measures of memory, to study effects of sleep on episodic memory consolidation in humans. During encoding before 10-h retention intervals that covered nighttime sleep or daytime wakefulness, two groups of young adults were presented with two episodes that were 1-h apart. Each episode entailed a spatial configuration of four different faces in a 3 × 3 grid of locations. After the retention interval, implicit spatio-temporal recall performance was assessed by eye-tracking visual exploration of another configuration of four faces of which two were from the first and second episode, respectively; of the two faces one was presented at the same location as during encoding and the other at another location. Afterward explicit verbal recall was assessed. Measures of implicit and explicit episodic memory retention were positively correlated (r = 0.57, P < 0.01), and were both better after nighttime sleep than daytime wakefulness (P < 0.05). In the sleep group, implicit episodic memory recall was associated with increased fast spindles during nonrapid eye movement (NonREM) sleep (r = 0.62, P < 0.05). Together with concordant observations in rats our results indicate that consolidation of genuinely episodic memory benefits from sleep.
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Affiliation(s)
- Frederik D Weber
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, 72076 Tübingen, Germany
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274
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Cox R, Tijdens RR, Meeter MM, Sweegers CCG, Talamini LM. Time, not sleep, unbinds contexts from item memory. PLoS One 2014; 9:e88307. [PMID: 24498441 PMCID: PMC3912211 DOI: 10.1371/journal.pone.0088307] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 01/07/2014] [Indexed: 01/24/2023] Open
Abstract
Contextual cues are known to benefit memory retrieval, but whether and how sleep affects this context effect remains unresolved. We manipulated contextual congruence during memory retrieval in human volunteers across 12 h and 24 h intervals beginning with either sleep or wakefulness. Our data suggest that whereas contextual cues lose their potency with time, sleep does not modulate this process. Furthermore, our results are consistent with the idea that sleep's beneficial effect on memory retention depends on the amount of waking time that has passed between encoding and sleep onset. The findings are discussed in the framework of competitive consolidation theory.
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Affiliation(s)
- Roy Cox
- Department of Psychology, University of Amsterdam, Amsterdam, the Netherlands
- Amsterdam Brain and Cognition, University of Amsterdam, Amsterdam, the Netherlands
- * E-mail:
| | - Ron R. Tijdens
- Department of Psychology, University of Amsterdam, Amsterdam, the Netherlands
| | - Martijn M. Meeter
- Department of Cognitive Psychology, VU University Amsterdam, Amsterdam, the Netherlands
| | - Carly C. G. Sweegers
- Department of Psychology, University of Amsterdam, Amsterdam, the Netherlands
- Amsterdam Brain and Cognition, University of Amsterdam, Amsterdam, the Netherlands
| | - Lucia M. Talamini
- Department of Psychology, University of Amsterdam, Amsterdam, the Netherlands
- Amsterdam Brain and Cognition, University of Amsterdam, Amsterdam, the Netherlands
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275
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Huber R, Born J. Sleep, synaptic connectivity, and hippocampal memory during early development. Trends Cogn Sci 2014; 18:141-52. [PMID: 24462334 DOI: 10.1016/j.tics.2013.12.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 12/06/2013] [Accepted: 12/10/2013] [Indexed: 01/01/2023]
Abstract
Sleep, specifically sleep slow-wave activity (SWA), contributes to global synaptic homeostasis in neocortical networks by downscaling synaptic connections that were potentiated during prior wakefulness. In parallel, SWA supports the consolidation of hippocampus-dependent episodic memory, a process linked to local increases in synaptic connectivity. During development, both SWA and episodic memory show parallel time courses: distinct SWA and capabilities to form episodic memory become established during infancy and then profoundly increase across childhood until puberty. We propose that the parallel increases across childhood reflect an imbalance in the underlying regulation of synaptic connectivity during sleep; although memory consolidation favoring synaptic potentiation is enhanced, global synaptic downscaling during sleep SWA does not attain complete recovery of homeostatic baseline levels.
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Affiliation(s)
- Reto Huber
- University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Jan Born
- University of Tübingen, Institute of Medical Psychology and Behavioral Neurobiology, Otfried-Mueller-Str. 25, 72076 Tübingen, Germany; University of Tübingen, Center for Integrative Neuroscience, Otfried-Mueller-Str. 25, 72076 Tübingen, Germany.
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276
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Cairney SA, Durrant SJ, Power R, Lewis PA. Complementary Roles of Slow-Wave Sleep and Rapid Eye Movement Sleep in Emotional Memory Consolidation. Cereb Cortex 2014; 25:1565-75. [DOI: 10.1093/cercor/bht349] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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277
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Beijamini F, Pereira SIR, Cini FA, Louzada FM. After being challenged by a video game problem, sleep increases the chance to solve it. PLoS One 2014; 9:e84342. [PMID: 24416219 PMCID: PMC3885559 DOI: 10.1371/journal.pone.0084342] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 11/14/2013] [Indexed: 11/18/2022] Open
Abstract
In the past years many studies have demonstrated the role of sleep on memory consolidation. It is known that sleeping after learning a declarative or non-declarative task, is better than remaining awake. Furthermore, there are reports of a possible role for dreams in consolidation of declarative memories. Other studies have reported the effect of naps on memory consolidation. With similar protocols, another set of studies indicated that sleep has a role in creativity and problem-solving. Here we hypothesised that sleep can increase the likelihood of solving problems. After struggling to solve a video game problem, subjects who took a nap (n = 14) were almost twice as likely to solve it when compared to the wake control group (n = 15). It is interesting to note that, in the nap group 9 out 14 subjects engaged in slow-wave sleep (SWS) and all solved the problem. Surprisingly, we did not find a significant involvement of Rapid Eye Movement (REM) sleep in this task. Slow-wave sleep is believed to be crucial for the transfer of memory-related information to the neocortex and implement intentions. Sleep can benefit problem-solving through the generalisation of newly encoded information and abstraction of the gist. In conclusion, our results indicate that sleep, even a nap, can potentiate the solution of problems that involve logical reasoning. Thus, sleep's function seems to go beyond memory consolidation to include managing of everyday-life events.
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Affiliation(s)
- Felipe Beijamini
- Laboratório de Cronobiologia Humana, Departamento de Fisiologia, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
- * E-mail:
| | - Sofia Isabel Ribeiro Pereira
- Laboratório de Cronobiologia Humana, Departamento de Fisiologia, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - Felipe Augusto Cini
- Laboratório de Cronobiologia Humana, Departamento de Fisiologia, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - Fernando Mazzilli Louzada
- Laboratório de Cronobiologia Humana, Departamento de Fisiologia, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
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278
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Tononi G, Cirelli C. Sleep and the price of plasticity: from synaptic and cellular homeostasis to memory consolidation and integration. Neuron 2014; 81:12-34. [PMID: 24411729 PMCID: PMC3921176 DOI: 10.1016/j.neuron.2013.12.025] [Citation(s) in RCA: 1269] [Impact Index Per Article: 126.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Sleep is universal, tightly regulated, and its loss impairs cognition. But why does the brain need to disconnect from the environment for hours every day? The synaptic homeostasis hypothesis (SHY) proposes that sleep is the price the brain pays for plasticity. During a waking episode, learning statistical regularities about the current environment requires strengthening connections throughout the brain. This increases cellular needs for energy and supplies, decreases signal-to-noise ratios, and saturates learning. During sleep, spontaneous activity renormalizes net synaptic strength and restores cellular homeostasis. Activity-dependent down-selection of synapses can also explain the benefits of sleep on memory acquisition, consolidation, and integration. This happens through the offline, comprehensive sampling of statistical regularities incorporated in neuronal circuits over a lifetime. This Perspective considers the rationale and evidence for SHY and points to open issues related to sleep and plasticity.
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Affiliation(s)
- Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
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279
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Genzel L, Kroes MC, Dresler M, Battaglia FP. Light sleep versus slow wave sleep in memory consolidation: a question of global versus local processes? Trends Neurosci 2014; 37:10-9. [DOI: 10.1016/j.tins.2013.10.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 10/07/2013] [Accepted: 10/08/2013] [Indexed: 01/06/2023]
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280
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Edwards CL, Ruby PM, Malinowski JE, Bennett PD, Blagrove MT. Dreaming and insight. Front Psychol 2013; 4:979. [PMID: 24550849 PMCID: PMC3872037 DOI: 10.3389/fpsyg.2013.00979] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 12/09/2013] [Indexed: 11/13/2022] Open
Abstract
This paper addresses claims that dreams can be a source of personal insight. Whereas there has been anecdotal backing for such claims, there is now tangential support from findings of the facilitative effect of sleep on cognitive insight, and of REM sleep in particular on emotional memory consolidation. Furthermore, the presence in dreams of metaphorical representations of waking life indicates the possibility of novel insight as an emergent feature of such metaphorical mappings. In order to assess whether personal insight can occur as a result of the consideration of dream content, 11 dream group discussion sessions were conducted which followed the Ullman Dream Appreciation technique, one session for each of 11 participants (10 females, 1 male; mean age = 19.2 years). Self-ratings of deepened self-perception and personal gains from participation in the group sessions showed that the Ullman technique is an effective procedure for establishing connections between dream content and recent waking life experiences, although wake life sources were found for only 14% of dream report text. The mean Exploration-Insight score on the Gains from Dream Interpretation questionnaire was very high and comparable to outcomes from the well-established Hill (1996) therapist-led dream interpretation method. This score was associated between-subjects with pre-group positive Attitude Toward Dreams (ATD). The need to distinguish “aha” experiences as a result of discovering a waking life source for part of a dream, from “aha” experiences of personal insight as a result of considering dream content, is discussed. Difficulties are described in designing a control condition to which the dream report condition can be compared.
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Affiliation(s)
| | - Perrine M Ruby
- Department of Psychology, Swansea University Swansea, UK ; Brain Dynamics and Cognition Team, Lyon Neuroscience Research Centre, INSERM U1028 Lyon, France
| | | | - Paul D Bennett
- Department of Psychology, Swansea University Swansea, UK
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281
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Henderson L, Weighall A, Gaskell G. Learning new vocabulary during childhood: Effects of semantic training on lexical consolidation and integration. J Exp Child Psychol 2013; 116:572-92. [DOI: 10.1016/j.jecp.2013.07.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 07/08/2013] [Accepted: 07/08/2013] [Indexed: 11/24/2022]
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282
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Albouy G, King BR, Maquet P, Doyon J. Hippocampus and striatum: Dynamics and interaction during acquisition and sleep-related motor sequence memory consolidation. Hippocampus 2013; 23:985-1004. [DOI: 10.1002/hipo.22183] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2013] [Indexed: 02/05/2023]
Affiliation(s)
- Geneviève Albouy
- Functional Neuroimaging Unit, C.R.I.U.G.M.; Montreal Quebec Canada
- Department of Psychology; University of Montreal; Montreal Quebec Canada
| | - Bradley R. King
- Functional Neuroimaging Unit, C.R.I.U.G.M.; Montreal Quebec Canada
- Department of Psychology; University of Montreal; Montreal Quebec Canada
| | - Pierre Maquet
- Cyclotron Research Centre, University of Liège; Liège Belgium
| | - Julien Doyon
- Functional Neuroimaging Unit, C.R.I.U.G.M.; Montreal Quebec Canada
- Department of Psychology; University of Montreal; Montreal Quebec Canada
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283
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Nere A, Hashmi A, Cirelli C, Tononi G. Sleep-dependent synaptic down-selection (I): modeling the benefits of sleep on memory consolidation and integration. Front Neurol 2013; 4:143. [PMID: 24137153 PMCID: PMC3786405 DOI: 10.3389/fneur.2013.00143] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Accepted: 09/12/2013] [Indexed: 11/27/2022] Open
Abstract
Sleep can favor the consolidation of both procedural and declarative memories, promote gist extraction, help the integration of new with old memories, and desaturate the ability to learn. It is often assumed that such beneficial effects are due to the reactivation of neural circuits in sleep to further strengthen the synapses modified during wake or transfer memories to different parts of the brain. A different possibility is that sleep may benefit memory not by further strengthening synapses, but rather by renormalizing synaptic strength to restore cellular homeostasis after net synaptic potentiation in wake. In this way, the sleep-dependent reactivation of neural circuits could result in the competitive down-selection of synapses that are activated infrequently and fit less well with the overall organization of memories. By using computer simulations, we show here that synaptic down-selection is in principle sufficient to explain the beneficial effects of sleep on the consolidation of procedural and declarative memories, on gist extraction, and on the integration of new with old memories, thereby addressing the plasticity-stability dilemma.
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Affiliation(s)
- Andrew Nere
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison , Madison, WI , USA
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284
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Wamsley EJ. Dreaming, waking conscious experience, and the resting brain: report of subjective experience as a tool in the cognitive neurosciences. Front Psychol 2013; 4:637. [PMID: 24065940 PMCID: PMC3779833 DOI: 10.3389/fpsyg.2013.00637] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 08/27/2013] [Indexed: 01/03/2023] Open
Abstract
Even when we are ostensibly doing “nothing”—as during states of rest, sleep, and reverie—the brain continues to process information. In resting wakefulness, the mind generates thoughts, plans for the future, and imagines fictitious scenarios. In sleep, when the demands of sensory input are reduced, our experience turns to the thoughts and images we call “dreaming.” Far from being a meaningless distraction, the content of these subjective experiences provides an important and unique source of information about the activities of the resting mind and brain. In both wakefulness and sleep, spontaneous experience combines recent and remote memory fragments into novel scenarios. These conscious experiences may reflect the consolidation of recent memory into long-term storage, an adaptive process that functions to extract general knowledge about the world and adaptively respond to future events. Recent examples from psychology and neuroscience demonstrate that the use of subjective report can provide clues to the function(s) of rest and sleep.
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Affiliation(s)
- Erin J Wamsley
- Department of Psychiatry, Center for Sleep and Cognition, Harvard Medical School and Beth Israel Deaconess Medical Center Boston, MA, USA
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285
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Coutanche MN, Gianessi CA, Chanales AJH, Willison KW, Thompson-Schill SL. The role of sleep in forming a memory representation of a two-dimensional space. Hippocampus 2013; 23:1189-97. [PMID: 23780782 DOI: 10.1002/hipo.22157] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2013] [Indexed: 11/08/2022]
Abstract
There is ample evidence from human and animal models that sleep contributes to the consolidation of newly learned information. The precise role of sleep for integrating information into interconnected memory representations is less well understood. Building on prior findings that following sleep (as compared to wakefulness) people are better able to draw inferences across learned associations in a simple hierarchy, we ask how sleep helps consolidate relationships in a more complex representational space. We taught 60 subjects spatial relationships between pairs of buildings, which (unknown to participants) formed a two-dimensional grid. Critically, participants were only taught a subset of the many possible spatial relations, which allowed them to potentially infer the remainder. After a 12 h period that either did or did not include a normal period of sleep, participants returned to the lab. We examined the quality of each participant's map of the two-dimensional space, and their knowledge of relative distances between buildings. After 12 h with sleep, subjects could more accurately map the full space than subjects who experienced only wakefulness. The incorporation of untaught, but inferable, associations was particularly improved. We further found that participants' distance judgment performance related to self-reported navigational style, but only after sleep. These findings demonstrate that consolidation over a night of sleep begins to integrate relations into an interconnected complex representation, in a way that supports spatial relational inference.
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Affiliation(s)
- Marc N Coutanche
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania
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286
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Affiliation(s)
- Marion Inostroza
- Department of Medical Psychology and Behavioral Neurobiology and Centre for Integrative Neuroscience (CIN), University of Tübingen, 72076 Tübingen, Germany; ,
- Departamento de Psicología, Universidad de Chile, Santiago, Chile
| | - Jan Born
- Department of Medical Psychology and Behavioral Neurobiology and Centre for Integrative Neuroscience (CIN), University of Tübingen, 72076 Tübingen, Germany; ,
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287
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Genzel L, Quack A, Jäger E, Konrad B, Steiger A, Dresler M. Complex motor sequence skills profit from sleep. Neuropsychobiology 2013; 66:237-43. [PMID: 23095374 DOI: 10.1159/000341878] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/16/2012] [Indexed: 11/19/2022]
Abstract
Simple motor memory has been shown to benefit from sleep; however, more complex motor skills have rarely been investigated so far. We investigated complex motor learning using a dance mat and choreographies in 36 healthy, young male subjects. Subjects performed one song and two new songs in three sessions distributed over 24 h to test sequence-specific learning and skill transfer. Each song had a unique choreography. One group learned the main song in the evening and was retested 12 and 24 h later on the main song and each one new song (PM-AM-PM). The second group underwent the same procedure; however, the first session was in the morning (AM-PM-AM). Thus, one group slept before the first retest (PM-AM-PM) while the other group slept between the first and the second retest (AM-PM-AM). Regarding sequence-specific learning, sleep induced a significant difference between the groups, which disappeared after both groups had slept. A significant transfer effect occurred independent of sleep. During both new songs, no difference between the groups was seen; however, the second and third songs were learned significantly faster than the first song. This study could show that complex motor sequence learning benefits from sleep while skill transfer seems to occur independently of sleep.
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Affiliation(s)
- Lisa Genzel
- Max Planck Institute of Psychiatry, Munich, Germany.
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288
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Caveats on psychological models of sleep and memory: A compass in an overgrown scenario. Sleep Med Rev 2013; 17:105-21. [DOI: 10.1016/j.smrv.2012.04.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 04/02/2012] [Accepted: 04/02/2012] [Indexed: 12/20/2022]
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289
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Abstract
Over more than a century of research has established the fact that sleep benefits the retention of memory. In this review we aim to comprehensively cover the field of "sleep and memory" research by providing a historical perspective on concepts and a discussion of more recent key findings. Whereas initial theories posed a passive role for sleep enhancing memories by protecting them from interfering stimuli, current theories highlight an active role for sleep in which memories undergo a process of system consolidation during sleep. Whereas older research concentrated on the role of rapid-eye-movement (REM) sleep, recent work has revealed the importance of slow-wave sleep (SWS) for memory consolidation and also enlightened some of the underlying electrophysiological, neurochemical, and genetic mechanisms, as well as developmental aspects in these processes. Specifically, newer findings characterize sleep as a brain state optimizing memory consolidation, in opposition to the waking brain being optimized for encoding of memories. Consolidation originates from reactivation of recently encoded neuronal memory representations, which occur during SWS and transform respective representations for integration into long-term memory. Ensuing REM sleep may stabilize transformed memories. While elaborated with respect to hippocampus-dependent memories, the concept of an active redistribution of memory representations from networks serving as temporary store into long-term stores might hold also for non-hippocampus-dependent memory, and even for nonneuronal, i.e., immunological memories, giving rise to the idea that the offline consolidation of memory during sleep represents a principle of long-term memory formation established in quite different physiological systems.
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Affiliation(s)
- Björn Rasch
- Division of Biopsychology, Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland.
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290
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Synaptic plasticity by antidromic firing during hippocampal network oscillations. Proc Natl Acad Sci U S A 2013; 110:5175-80. [PMID: 23479613 DOI: 10.1073/pnas.1210735110] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Learning and other cognitive tasks require integrating new experiences into context. In contrast to sensory-evoked synaptic plasticity, comparatively little is known of how synaptic plasticity may be regulated by intrinsic activity in the brain, much of which can involve nonclassical modes of neuronal firing and integration. Coherent high-frequency oscillations of electrical activity in CA1 hippocampal neurons [sharp-wave ripple complexes (SPW-Rs)] functionally couple neurons into transient ensembles. These oscillations occur during slow-wave sleep or at rest. Neurons that participate in SPW-Rs are distinguished from adjacent nonparticipating neurons by firing action potentials that are initiated ectopically in the distal region of axons and propagate antidromically to the cell body. This activity is facilitated by GABA(A)-mediated depolarization of axons and electrotonic coupling. The possible effects of antidromic firing on synaptic strength are unknown. We find that facilitation of spontaneous SPW-Rs in hippocampal slices by increasing gap-junction coupling or by GABA(A)-mediated axon depolarization resulted in a reduction of synaptic strength, and electrical stimulation of axons evoked a widespread, long-lasting synaptic depression. Unlike other forms of synaptic plasticity, this synaptic depression is not dependent upon synaptic input or glutamate receptor activation, but rather requires L-type calcium channel activation and functional gap junctions. Synaptic stimulation delivered after antidromic firing, which was otherwise too weak to induce synaptic potentiation, triggered a long-lasting increase in synaptic strength. Rescaling synaptic weights in subsets of neurons firing antidromically during SPW-Rs might contribute to memory consolidation by sharpening specificity of subsequent synaptic input and promoting incorporation of novel information.
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291
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292
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The sleeping child outplays the adult's capacity to convert implicit into explicit knowledge. Nat Neurosci 2013; 16:391-3. [PMID: 23434910 DOI: 10.1038/nn.3343] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 01/24/2013] [Indexed: 02/05/2023]
Abstract
When sleep followed implicit training on a motor sequence, children showed greater gains in explicit sequence knowledge after sleep than adults. This greater explicit knowledge in children was linked to their higher sleep slow-wave activity and to stronger hippocampal activation at explicit knowledge retrieval. Our data indicate the superiority of children in extracting invariant features from complex environments, possibly as a result of enhanced reprocessing of hippocampal memory representations during slow-wave sleep.
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293
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Consolidation differentially modulates schema effects on memory for items and associations. PLoS One 2013; 8:e56155. [PMID: 23409144 PMCID: PMC3567062 DOI: 10.1371/journal.pone.0056155] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 01/07/2013] [Indexed: 12/22/2022] Open
Abstract
Newly learned information that is congruent with a preexisting schema is often better remembered than information that is incongruent. This schema effect on memory has previously been associated to more efficient encoding and consolidation mechanisms. However, this effect is not always consistently supported in the literature, with differential schema effects reported for different types of memory, different retrieval cues, and the possibility of time-dependent effects related to consolidation processes. To examine these effects more directly, we tested participants on two different types of memory (item recognition and associative memory) for newly encoded visuo-tactile associations at different study-test intervals, thus probing memory retrieval accuracy for schema-congruent and schema-incongruent items and associations at different time points (t = 0, t = 20, and t = 48 hours) after encoding. Results show that the schema effect on visual item recognition only arises after consolidation, while the schema effect on associative memory is already apparent immediately after encoding, persisting, but getting smaller over time. These findings give further insight into different factors influencing the schema effect on memory, and can inform future schema experiments by illustrating the value of considering effects of memory type and consolidation on schema-modulated retrieval.
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294
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Spencer RMC. Neurophysiological Basis of Sleep's Function on Memory and Cognition. ISRN PHYSIOLOGY 2013; 2013:619319. [PMID: 24600607 PMCID: PMC3940073 DOI: 10.1155/2013/619319] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A wealth of recent studies support a function of sleep on memory and cognitive processing. At a physiological level, sleep supports memory in a number of ways including neural replay and enhanced plasticity in the context of reduced ongoing input. This paper presents behavioral evidence for sleep's role in selective remembering and forgetting of declarative memories, in generalization of these memories, and in motor skill consolidation. Recent physiological data reviewed suggests how these behavioral changes might be supported by sleep. Importantly, in reviewing these findings, an integrated view of how distinct sleep stages uniquely contribute to memory processing emerges. This model will be useful in developing future behavioral and physiological studies to test predictions that emerge.
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Affiliation(s)
- Rebecca M C Spencer
- Department of Psychology and Neuroscience and Behavior Program, University of Massachusetts, Amherst 419 Tobin Hall, 135 Hicks Way, Amherst, MA 01003, USA
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295
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Inostroza M, Binder S, Born J. Sleep-dependency of episodic-like memory consolidation in rats. Behav Brain Res 2013; 237:15-22. [DOI: 10.1016/j.bbr.2012.09.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 09/07/2012] [Accepted: 09/11/2012] [Indexed: 10/27/2022]
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296
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Generalizing memories over time: sleep and reinforcement facilitate transitive inference. Neurobiol Learn Mem 2012; 100:70-6. [PMID: 23257278 DOI: 10.1016/j.nlm.2012.12.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 11/03/2012] [Accepted: 12/09/2012] [Indexed: 10/27/2022]
Abstract
The use of reinforcement and rewards is known to enhance memory retention. However, the impact of reinforcement on higher-order forms of memory processing, such as integration and generalization, has not been directly manipulated in previous studies. Furthermore, there is evidence that sleep enhances the integration and generalization of memory, but these studies have only used reinforcement learning paradigms and have not examined whether reinforcement impacts or is critical for memory integration and generalization during sleep. Thus, the aims of the current study were to examine: (1) whether reinforcement during learning impacts the integration and generalization of memory; and (2) whether sleep and reinforcement interact to enhance memory integration and generalization. We investigated these questions using a transitive inference (TI) task, which is thought to require the integration and generalization of disparate relational memories in order to make novel inferences. To examine whether reinforcement influences or is required for the formation of inferences, we compared performance using a reinforcement or an observation based TI task. We examined the impact of sleep by comparing performance after a 12-h delay containing either wake or sleep. Our results showed that: (1) explicit reinforcement during learning is required to make transitive inferences and that sleep further enhances this effect; (2) sleep does not make up for the inability to make inferences when reinforcement does not occur during learning. These data expand upon previous findings and suggest intriguing possibilities for the mechanisms involved in sleep-dependent memory transformation.
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297
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Durrant SJ, Cairney SA, Lewis PA. Overnight consolidation aids the transfer of statistical knowledge from the medial temporal lobe to the striatum. ACTA ACUST UNITED AC 2012; 23:2467-78. [PMID: 22879350 DOI: 10.1093/cercor/bhs244] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Sleep is important for abstraction of the underlying principles (or gist) which bind together conceptually related stimuli, but little is known about the neural correlates of this process. Here, we investigate this issue using overnight sleep monitoring and functional magnetic resonance imaging (fMRI). Participants were exposed to a statistically structured sequence of auditory tones then tested immediately for recognition of short sequences which conformed to the learned statistical pattern. Subsequently, after consolidation over either 30 min or 24h, they performed a delayed test session in which brain activity was monitored with fMRI. Behaviorally, there was greater improvement across 24h than across 30 min, and this was predicted by the amount of slow wave sleep (SWS) obtained. Functionally, we observed weaker parahippocampal responses and stronger striatal responses after sleep. Like the behavioral result, these differences in functional response were predicted by the amount of SWS obtained. Furthermore, connectivity between striatum and parahippocampus was weaker after sleep, whereas connectivity between putamen and planum temporale was stronger. Taken together, these findings suggest that abstraction is associated with a gradual shift from the hippocampal to the striatal memory system and that this may be mediated by SWS.
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Affiliation(s)
- Simon J Durrant
- School of Psychology, Bridge House, University of Lincoln, Lincoln LN6 7TS, UK and
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298
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Kroes MC, Fernández G. Dynamic neural systems enable adaptive, flexible memories. Neurosci Biobehav Rev 2012; 36:1646-66. [DOI: 10.1016/j.neubiorev.2012.02.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Revised: 02/07/2012] [Accepted: 02/20/2012] [Indexed: 10/28/2022]
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299
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Wikenheiser AM, Redish AD. The balance of forward and backward hippocampal sequences shifts across behavioral states. Hippocampus 2012; 23:22-9. [PMID: 22736562 DOI: 10.1002/hipo.22049] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2012] [Indexed: 11/08/2022]
Abstract
Place cell firing patterns in the rat hippocampus are often organized as sequences. Sequences falling within cycles of the theta (6-10 Hz) local field potential (LFP) oscillation represent segments of ongoing behavioral trajectories. Sequences expressed during sharp wave ripple (SWR) complexes represent spatial trajectories through the environment, in both the same direction as actual trajectories (forward sequences) and in an ordering opposite that of behavior (backward sequences). Although hippocampal sequences could fulfill unique functional roles depending on the direction of the sequence and the animal's state when the sequence occurs, quantitative comparisons of sequence direction across behavioral and physiological states within the same experiment, employing consistent methodology, are lacking. Here, we used cross-correlation and Bayesian decoding to measure the direction of hippocampal sequences in rats during active behavior, awake rest and slow-wave sleep. During pretask sleep, few sequences were detected in either direction. Sequences within theta cycles during active behavior were overwhelmingly forward. Sequences during quiescent moments of behavior were both forward and backward, in equal proportion. During postbehavior sleep, sequences were again expressed in both directions, but significantly more forward than backward sequences were detected. The shift in the balance of sequence direction could reflect changing functional demands on the hippocampal network across behavioral and physiological states.
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Affiliation(s)
- Andrew M Wikenheiser
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA
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300
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Saletin JM, Walker MP. Nocturnal mnemonics: sleep and hippocampal memory processing. Front Neurol 2012; 3:59. [PMID: 22557988 PMCID: PMC3340569 DOI: 10.3389/fneur.2012.00059] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 03/28/2012] [Indexed: 11/20/2022] Open
Abstract
As critical as waking brain function is to learning and memory, an established literature now describes an equally important yet complementary role for sleep in information processing. This overview examines the specific contribution of sleep to human hippocampal memory processing; both the detriments caused by a lack of sleep, and conversely, the proactive benefits that develop following the presence of sleep. First, a role for sleep before learning is discussed, preparing the hippocampus for initial memory encoding. Second, a role for sleep after learning is considered, modulating the post-encoding consolidation of hippocampal-dependent memory. Third, a model is outlined in which these encoding and consolidation operations are symbiotically accomplished, associated with specific NREM sleep physiological oscillations. As a result, the optimal network outcome is achieved: increasing hippocampal independence and hence overnight consolidation, while restoring next-day sparse hippocampal encoding capacity for renewed learning ability upon awakening. Finally, emerging evidence is considered suggesting that, unlike previous conceptions, sleep does not universally consolidate all information. Instead, and based on explicit as well as saliency cues during initial encoding, sleep executes the discriminatory offline consolidation only of select information. Consequently, sleep promotes the targeted strengthening of some memories while actively forgetting others; a proposal with significant theoretical and clinical ramifications.
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Affiliation(s)
- Jared M Saletin
- Sleep and Neuroimaging Laboratory, Department of Psychology, University of California Berkeley, CA, USA
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