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Query: UNIPROT:O75628 (REM)
 5,581 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Morphine effects on many neural and behavioral measures, including tests of learning and memory, are attenuated by increased circulating glucose levels. Using systemic injections, we investigated the ability of glucose to attenuate sleep deficits induced by morphine administration in the rat. Morphine at 1 mg/kg produced a moderate decrease in slow wave sleep which was prevented by concomitant administration of 100 mg/kg of glucose. A higher dose of morphine (10 mg/kg) severely delayed the onset of both slow wave sleep and REM sleep. These delays were attenuated by concurrent administration of 250 mg/kg of glucose. Thus, glucose reversals of morphine effects are also extended to measures of sleep.
Neurobiol Learn Mem 1995 Sep
PMID:Morphine-induced deficits in sleep patterns: attenuation by glucose. 758 21

Rare words are usually better recognized than common words, a finding in recognition memory known as the word-frequency effect. Some theories predict the word-frequency effect because they assume that rare words consist of more distinctive features than do common words (e.g., Shiffrin & Steyvers's, 1997, REM theory). In this study, recognition memory was tested for words that vary in the commonness of their orthographic features, and we found that recognition was best for words made up of primarily rare letters. In addition, a mirror effect was observed: Words with rare letters had a higher hit rate and a lower false-alarm rate than did words with common letters. We also found that normative word frequency affects recognition independently of letter frequency. Therefore, the distinctiveness of a word's orthographic features is one, but not the only, factor necessary to explain the word-frequency effect.
Mem Cognit 2002 Jun
PMID:Feature frequency effects in recognition memory. 1218 62

The positive effect of postlearning sleep on memory consolidation as well as the relationship between sleep-related memory processes and the hippocampal formation are increasingly clarified topics in neurobiology. However, the possibility of a stable relationship between waking mnemonic performance and sleep-dependent hippocampal electric activity is unexplored. Here we report a correlative analysis between sleep-dependent parahippocampal-hippocampal (pHip-Hip) electric activity recorded by foramen ovale (FO) electrodes and different types of memory performances in epileptic patients. Psychological testing was performed days or weeks before electrophysiological recordings. The relative spectral power of the slow activity (below 1.25 Hz) during deep non-REM (NREM) sleep at the right pHip-Hip region correlated positively with the visual memory performance according to Rey-Osterrieth Complex Figure Test (ROCFT). Along the posterior-anterior direction of the hippocampal formation a linear increasing of correlations was observed. The relative power of the activity below 1.25 Hz at the left pHip-Hip during phasic REM sleep correlated positively with verbal learning performance and mnemonic retention values according to ROCFT. It is concluded that the pHip-Hip structures' capacity of producing high amplitude and synchronized slow (< 1 Hz) oscillation during deep NREM sleep is related to the functional power of these structures. We hypothesize that the asymmetric (side-specific) propagation of ponto-geniculo-occipital (PGO) activity to the pHip-Hip region is related to the memory correlates of phasic REM sleep.
Neurobiol Learn Mem 2002 Sep
PMID:Sleep-dependent hippocampal slow activity correlates with waking memory performance in humans. 1243 28

Recent neuroimaging studies show that human REM sleep is characterized by a specific pattern of regional brain activity. While being usually interpreted in relation to physiological and cellular mechanisms, the regionally-specific distribution of brain activity during REM sleep may also be linked to specific dream features. Remarkably, several bizarre features of dreams present similarities with wellknown neuropsychological syndromes after brain damage, such as delusional misidentifications for faces and places. We propose that neuropsychological analysis of dream content might offer new ways of interpreting neuroimaging maps, as well as specific predictions for future neuroimaging studies.
Bull Mem Acad R Med Belg 2002
PMID:[Evaluation of dreams by the neuropsychological approach. Utility in the characterization of cerebral correlates in oneiric activity by functional neuroimaging]. 1250 17

Judgments of frequency for targets (old items) and foils (similar; dissimilar) steadily increase as the number of times a target is studied increases, but discrimination of targets from similar foils does not steadily improve, a phenomenon termed registration without learning (D. L. Hintzman & T. Curran, 1995; D. L. Hintzman, T. Curran, & B. Oppy, 1992). The present experiment explores this phenomenon with words of differing normative word frequency. The retrieving-effectively-from-memory model (REM; R. M. Shifrrin & M. Steyvers, 1997, 1998) predicts that low-frequency words will be better recognized than high-frequency words because low-frequency words have more distinctive memory representations. A corollary of this assumption predicts that the typical recognition word-frequency effect will be disrupted when similar foils are tested. These predictions were confirmed, but to fit both the recognition and the judgment-of-frequency data, the authors used a "dual-process" extension of the REM model.
J Exp Psychol Learn Mem Cogn 2004 Mar
PMID:Modeling the effects of repetitions, similarity, and normative word frequency on old-new recognition and judgments of frequency. 138 8

The group of papers on memory reactivation and consolidation during sleep included in this volume represents cutting edge work in both animals and humans. They support that the two types of sleep serve different necessary functions. The role of slow wave sleep (SWS) is reactivation of the hippocampal-neocortical circuits activated during a waking learning period, while REM sleep is responsible for the consolidation of this new learning into long-term memory. These studies provide further insights into mechanisms involved in brain plasticity. Robeiro has demonstrated the upregulation of an immediate-early gene (IEG zif 268) to waking levels, which occurs only in REM and only in connection with new learning. McNaughton and his group have identified electrical indicators that the hippocampus and neocortex are talking to each other by testing the coactivation of hippocampal sharp wave bursts in SWS and shifts from down to up states of activation in the neocortex. In human studies Smith's group reports work on individual differences such as intelligence and presleep alcohol that affect postsleep performance, and Stickgold and collaborators report that a short nap will improve performance if it contains REM sleep. Payne and Nadel suggest that the recall benefit associated with REM sleep may be due to its association with increased cortisol levels. These papers are important not only in their individual contributions but also in revitalizing the work coordinating waking and sleep. This promises to further the understanding of how our unique capacity to learn from experience and modify our behavior takes place.
Learn Mem
PMID:The role of sleep in changing our minds: a psychologist's discussion of papers on memory reactivation and consolidation in sleep. 1557 82

In mammals and birds, long episodes of nondreaming sleep ("slow-wave" sleep, SW) are followed by short episodes of dreaming sleep ("rapid-eye-movement" sleep, REM). Both SW and REM sleep have been shown to be important for the consolidation of newly acquired memories, but the underlying mechanisms remain elusive. Here we review electrophysiological and molecular data suggesting that SW and REM sleep play distinct and complementary roles on memory consolidation: While postacquisition neuronal reverberation depends mainly on SW sleep episodes, transcriptional events able to promote long-lasting memory storage are only triggered during ensuing REM sleep. We also discuss evidence that the wake-sleep cycle promotes a postsynaptic propagation of memory traces away from the neural sites responsible for initial encoding. Taken together, our results suggest that basic molecular and cellular mechanisms underlie the reverberation, storage, and propagation of memory traces during sleep. We propose that these three processes alone may account for several important properties of memory consolidation over time, such as deeper memory encoding within the cerebral cortex, incremental learning several nights after memory acquisition, and progressive hippocampal disengagement.
Learn Mem
PMID:Reverberation, storage, and postsynaptic propagation of memories during sleep. 1557 86

Sleep is thought to participate in the consolidation of recent memory traces. We tested this hypothesis in humans, using functional neuroimaging (functional magnetic resonance imaging and positron emission tomography). First, following the training on a procedural visuo-motor learning task (pursuit task), total sleep deprivation on the first post-training night significantly deteriorates the gain in performance, which is usually observed after one complete night of sleep. In parallel, sleep deprivation hampers the changes in functional segregation and connectivity, which underpin the gain in performance usually observed in subjects allowed to sleep on the first post-training night. Second, following the training on an implicit memory task (probabilistic serial reaction time task), some brain areas are reactivated during REM sleep on the first post-training night. The reactivation was shown to be related to the processing of high-level material and to be modulated by the amount of learning achieved during the training session. These changes in activity do not involve isolated brain areas but entire macroscopic cortico-subcortical networks. Taken together, the results suggest an off-line processing of recent memory traces during sleep.
Bull Mem Acad R Med Belg 2004
PMID:A role for sleep in the processing of memory traces. Contribution of functional neuroimaging in humans. 1561 89

Recognition memory is considered to be supported by two different memory processes, i.e., the explicit recollection of information about a previous event and an implicit process of recognition based on an acontextual sense of familiarity. Both types of memory supposedly rely on distinct memory systems. Sleep is known to enhance the consolidation of memories, with the different sleep stages affecting different types of memory. In the present study, we used the process-dissociation procedure to compare the effects of sleep on estimates of explicit (recollection) and implicit (familiarity) memory formation on a word-list discrimination task. Subjects studied two lists of words before a 3-h retention interval of sleep or wakefulness, and recognition was tested afterward. The retention intervals were positioned either in the early night when sleep is dominated by slow-wave sleep (SWS), or in the late night, when sleep is dominated by REM sleep. Sleep enhanced explicit recognition memory, as compared with wakefulness (P < 0.05), whereas familiarity was not affected by sleep. Moreover, explicit recognition was particularly enhanced after sleep in the early-night retention interval, and especially when the words were presented with the same contextual features as during learning, i.e., in the same font (P < 0.05). The data indicate that in a task that allows separating the contribution of explicit and implicit memory, sleep particularly supports explicit memory formation. The mechanism of this effect appears to be linked to SWS.
Learn Mem
PMID:Sleep enhances explicit recollection in recognition memory. 1568 30

The specialized role that sleep-specific brain physiology plays in memory processing is being rapidly clarified with a greater understanding of the dynamic, complex, and exquisitely orchestrated brain state that emerges during sleep. Behaviorally, the facilitative role of non-REM (NREM) sleep (primarily slow wave sleep) for declarative but not procedural memory performance in humans has been demonstrated in a number of nocturnal sleep studies. However, subjects in these studies were tested after periods of sleep that contained REM sleep in addition to NREM sleep, and comparison wake groups were subjected to mild sleep deprivation. To add some clarity to the findings of these nocturnal studies, we assessed performance on declarative and procedural memory tasks following a daytime training-retest interval containing either a short nap that included NREM without REM sleep, or wakefulness. Consistent with previous findings we show that, after a comparatively brief sleep episode, subjects that take a nap improve more on a declarative memory task than subjects that stay awake, but that improvement on a procedural memory task is the same regardless of whether subjects take a nap or remain awake. Slow wave sleep was the only sleep parameter to correlate positively with declarative memory improvement. These findings are discussed with reference to the general benefits of napping and within the broader context of a growing literature suggesting a role for NREM-specific physiology for the processing of declarative memory.
Neurobiol Learn Mem 2006 Sep
PMID:A daytime nap containing solely non-REM sleep enhances declarative but not procedural memory. 1664 82


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