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  • 1
    Online Resource
    Online Resource
    Wiley ; 2017
    In:  Journal of Sleep Research Vol. 26, No. 5 ( 2017-10), p. 629-640
    In: Journal of Sleep Research, Wiley, Vol. 26, No. 5 ( 2017-10), p. 629-640
    Abstract: Polysomnographic recording of night sleep was carried out in 15 patients with the diagnosis vegetative state (syn. unresponsive wakefulness syndrome). Sleep scoring was performed by three raters, and confirmed by means of a spectral power analysis of the electroencephalogram, electrooculogram and electromyogram. All patients but one exhibited at least some signs of sleep. In particular, sleep stage N1 was found in 13 patients, N2 in 14 patients, N3 in nine patients, and rapid eye movement sleep in 10 patients. Three patients exhibited all phenomena characteristic for normal sleep, including spindles and rapid eye movements. However, in all but one patient, sleep patterns were severely disturbed as compared with normative data. All patients had frequent and long periods of wakefulness during the night. In some apparent rapid eye movement sleep episodes, no eye movements were recorded. Sleep spindles were detected in five patients only, and their density was very low. We conclude that the majority of vegetative state patients retain some important circadian changes. Further studies are necessary to disentangle multiple factors potentially affecting sleep pattern of vegetative state patients.
    Type of Medium: Online Resource
    ISSN: 0962-1105 , 1365-2869
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2017
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  • 2
    Online Resource
    Online Resource
    American Diabetes Association ; 2007
    In:  Diabetes Vol. 56, No. 7 ( 2007-07-01), p. 1938-1942
    In: Diabetes, American Diabetes Association, Vol. 56, No. 7 ( 2007-07-01), p. 1938-1942
    Abstract: OBJECTIVE—Nocturnal hypoglycemia represents an important problem for diabetic patients, which has been primarily attributed to an attenuated hormonal counterregulation during sleep. So far, hypoglycemia counterregulation has been exclusively examined during early nocturnal sleep, although early sleep differs markedly in sleep stage architecture from late sleep. Here, we investigated whether awakening and counterregulatory responses differ between early and late sleep. RESEARCH DESIGN AND METHODS—Sixteen healthy subjects were tested on three occasions. On two nights, a linear fall in plasma glucose to a nadir of 2.2 mmol/l within 60 min was induced by insulin infusion. On one night, this was done immediately after sleep onset and on the other night after ∼3.5 h of sleep. In a further control night, no hypoglycemia was induced. RESULTS—During early sleep, 10 subjects awoke in response to hypoglycemia, whereas no subject awoke during the corresponding interval of the control night (P & lt; 0.004). During late sleep, all subjects awoke upon hypoglycemia, and four subjects awoke spontaneously during the corresponding control interval (P & lt; 0.001). The pattern indicates that the frequency of awakenings caused by hypoglycemia is similar for early and late sleep. Increases in epinephrine, norepinephrine, ACTH, cortisol, and growth hormone were distinctly weaker during late than early hypoglycemia (all P & lt; 0.05). CONCLUSIONS—Diminished hormonal counterregulation during late sleep could be one factor contributing to the clinically observed accumulation of hypoglycemic episodes in the later part of the night in patients with diabetes.
    Type of Medium: Online Resource
    ISSN: 0012-1797 , 1939-327X
    Language: English
    Publisher: American Diabetes Association
    Publication Date: 2007
    detail.hit.zdb_id: 1501252-9
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  • 3
    Online Resource
    Online Resource
    MIT Press ; 2006
    In:  Journal of Cognitive Neuroscience Vol. 18, No. 5 ( 2006-05-01), p. 793-802
    In: Journal of Cognitive Neuroscience, MIT Press, Vol. 18, No. 5 ( 2006-05-01), p. 793-802
    Abstract: High central nervous system levels of acetylcholine (ACh) are commonly regarded as crucial for learning and memory, and a decline in cholinergic neurotransmission is associated with Alzheimer's dementia. However, recent findings revealed exceptions to this rule: The low ACh tone characterizing slowwave sleep (SWS) has proven necessary for consolidation of hippocampus-dependent declarative memories during this sleep stage. Such observations, together with recent models of a hippocampal-neocortical dialogue underlying systems memory consolidation, suggest that high levels of ACh support memory encoding, whereas low levels facilitate consolidation. We tested this hypothesis in human subjects by blocking cholinergic neurotransmission during wakefulness, starting 30 min after learning. Subjects received the muscarinic antagonist scopolamine (4 µg/kg bodyweight intravenously) and the nicotinic antagonist mecamylamine (5 mg orally). Compared to placebo, combined muscarinic and nicotinic receptor blockade significantly improved consolidation of declarative memories tested 10 hr later, but simultaneously impaired acquisition of similar material. Consolidation of procedural memories, which are not dependent on hippocampal functioning, was unaffected. Neither scopolamine nor mecamylamine alone enhanced declarative memory consolidation. Our findings support the notion that ACh acts as a switch between modes of acquisition and consolidation. We propose that the natural shift in central nervous system cholinergic tone from high levels during wakefulness to minimal levels during SWS optimizes declarative memory consolidation during a period with no need for new memory encoding.
    Type of Medium: Online Resource
    ISSN: 0898-929X , 1530-8898
    Language: English
    Publisher: MIT Press
    Publication Date: 2006
    SSG: 5,2
    SSG: 7,11
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  • 4
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2005
    In:  Sleep Vol. 28, No. 9 ( 2005-09), p. 1109-1115
    In: Sleep, Oxford University Press (OUP), Vol. 28, No. 9 ( 2005-09), p. 1109-1115
    Type of Medium: Online Resource
    ISSN: 1550-9109 , 0161-8105
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
    detail.hit.zdb_id: 2056761-3
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  • 5
    Online Resource
    Online Resource
    Cold Spring Harbor Laboratory ; 2004
    In:  Learning & Memory Vol. 11, No. 6 ( 2004-11), p. 679-685
    In: Learning & Memory, Cold Spring Harbor Laboratory, Vol. 11, No. 6 ( 2004-11), p. 679-685
    Abstract: Of late, an increasing number of studies have shown a strong relationship between sleep and memory. Here we summarize a series of our own studies in humans supporting a beneficial influence of slow-wave sleep (SWS) on declarative memory formation, and try to identify some mechanisms that might underlie this influence. Specifically, these experiments show that declarative memory benefits mainly from sleep periods dominated by SWS, whereas there is no consistent benefit of this memory from periods rich in rapid eye movement (REM) sleep. A main mechanism of declarative memory formation is believed to be the reactivation of newly acquired memory representations in hippocampal networks that stimulates a transfer and integration of these representations into neocortical neuronal networks. Consistent with this model, spindle activity and slow oscillation-related EEG coherence increase during early sleep after intense declarative learning in humans, signs that together point toward a neocortical reprocessing of the learned material. In addition, sleep seems to provide an optimal milieu for declarative memory reprocessing and consolidation by reducing cholinergic activation and the cortisol feedback to the hippocampus during SWS.
    Type of Medium: Online Resource
    ISSN: 1072-0502 , 1549-5485
    Language: English
    Publisher: Cold Spring Harbor Laboratory
    Publication Date: 2004
    detail.hit.zdb_id: 2022057-1
    SSG: 12
    SSG: 5,2
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  • 6
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2004
    In:  Proceedings of the National Academy of Sciences Vol. 101, No. 7 ( 2004-02-17), p. 2140-2144
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 101, No. 7 ( 2004-02-17), p. 2140-2144
    Abstract: The neurotransmitter acetylcholine is considered essential for proper functioning of the hippocampus-dependent declarative memory system, and it represents a major neuropharmacological target for the treatment of memory deficits, such as those in Alzheimer's disease. During slow-wave sleep (SWS), however, declarative memory consolidation is particularly strong, while acetylcholine levels in the hippocampus drop to a minimum. Observations in rats led to the hypothesis that the low cholinergic tone during SWS is necessary for the replay of new memories in the hippocampus and their long-term storage in neocortical networks. However, this low tone should not affect nondeclarative memory systems. In this study, increasing central nervous cholinergic activation during SWS-rich sleep by posttrial infusion of 0.75 mg of the cholinesterase inhibitor physostigmine completely blocked SWS-related consolidation of declarative memories for word pairs in human subjects. The treatment did not interfere with consolidation of a nondeclarative mirror tracing task. Also, physostigmine did not alter memory consolidation during waking, when the endogenous central nervous cholinergic tone is maximal. These findings are in line with predictions that a low cholinergic tone during SWS is essential for declarative memory consolidation.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2004
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 7
    In: Cerebral Cortex, Oxford University Press (OUP), Vol. 25, No. 11 ( 2015-11), p. 4610-4618
    Type of Medium: Online Resource
    ISSN: 1047-3211 , 1460-2199
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2015
    detail.hit.zdb_id: 1483485-6
    SSG: 12
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  • 8
    In: Metabolism, Elsevier BV, Vol. 53, No. 7 ( 2004-7), p. 894-898
    Type of Medium: Online Resource
    ISSN: 0026-0495
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2004
    detail.hit.zdb_id: 2049062-8
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  • 9
    In: Psychoneuroendocrinology, Elsevier BV, Vol. 30, No. 5 ( 2005-6), p. 496-504
    Type of Medium: Online Resource
    ISSN: 0306-4530
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2005
    detail.hit.zdb_id: 1500706-6
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  • 10
    Online Resource
    Online Resource
    SAGE Publications ; 2006
    In:  The Neuroscientist Vol. 12, No. 5 ( 2006-10), p. 410-424
    In: The Neuroscientist, SAGE Publications, Vol. 12, No. 5 ( 2006-10), p. 410-424
    Abstract: Recently, compelling evidence has accumulated that links sleep to learning and memory. Sleep has been identified as a state that optimizes the consolidation of newly acquired information in memory. Consolidation is an active process that is presumed to rely on the covert reactivation and reorganization of newly encoded representations. Hippocampus-dependent memories benefit primarily from slow-wave sleep (SWS), whereas memories not depending on the hippocampus show greater gains over periods containing high amounts of rapid eye movement sleep. One way sleep does this is by establishing different patterns of neurotransmitters and neurohormone secretion between sleep stages. Another central role for consolidating memories is played by the slow oscillation, that is, the oscillating field potential change dominating SWS. The emergence of slow oscillations in neocortical networks depends on the prior use of these networks for encoding of information. Via efferent pathways, they synchronize the occurrence of sharp wave ripples accompanying memory reactivations in the hippocampus with thalamocortical spindle activity. Thus, hippocampal memories are fed back into neocortical networks at a time when these networks are depolarized and, because of concurrent spindle activity, can most sensitively react to these inputs with plastic changes underlying the formation of long-term memory representations.
    Type of Medium: Online Resource
    ISSN: 1073-8584 , 1089-4098
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
    detail.hit.zdb_id: 2029471-2
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