Sleep: The Ebb and Flow of Memory Consolidation

Department of Psychiatry, Harvard Medical School and Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston, MA, USA.
Current Biology (Impact Factor: 9.57). 06/2008; 18(10):R423-5. DOI: 10.1016/j.cub.2008.03.022
Source: PubMed


A new study has shown that successful imprinting in domestic chicks depends on post-training sleep; individual neurons were found to enter, leave and then rejoin neural networks, and may constitute the memory trace of the imprinted stimulus.

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    • "Sleep is a complex phenotype that involves several neurochemical and physiological processes. It is known to perform restorative functions and to facilitate memory consolidation [1,2]. Although sleep is essential for overall well-being and optimal physical and psychological functioning, chronic sleep restriction is frequently experienced due to contemporary social and domestic responsibilities, medical conditions and sleep disorders [3]. "
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    ABSTRACT: Sleep is a restorative process and is essential for maintenance of mental and physical health. In an attempt to understand the complexity of sleep, multidisciplinary strategies, including genetic approaches, have been applied to sleep research. Although quantitative real time PCR has been used in previous sleep-related gene expression studies, proper validation of reference genes is currently lacking. Thus, we examined the effect of total or paradoxical sleep deprivation (TSD or PSD) on the expression stability of the following frequently used reference genes in brain and blood: beta-actin (b-actin), beta-2-microglobulin (B2M), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and hypoxanthine guanine phosphoribosyl transferase (HPRT). Neither TSD nor PSD affected the expression stability of all tested genes in both tissues indicating that b-actin, B2M, GAPDH and HPRT are appropriate reference genes for the sleep-related gene expression studies. In order to further verify these results, the relative expression of brain derived neurotrophic factor (BDNF) and glycerol-3-phosphate dehydrogenase1 (GPD1) was evaluated in brain and blood, respectively. The normalization with each of four reference genes produced similar pattern of expression in control and sleep deprived rats, but subtle differences in the magnitude of expression fold change were observed which might affect the statistical significance. This study demonstrated that sleep deprivation does not alter the expression stability of commonly used reference genes in brain and blood. Nonetheless, the use of multiple reference genes in quantitative RT-PCR is required for the accurate results.
    Full-text · Article · Feb 2009 · BMC Molecular Biology
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    • "However, unihemispheric sleep in birds may function not only in vigilance against predators but in some birds (i.e. domestic chicks, Gallus galllus domesticus) also in monitoring the environment and the positions of the hen, brood siblings and imprinting objects; it may also have a physiological restoring function (local sleep; Mascetti et al. 1999, 2004; Mascetti & Vallortigara 2001; Bobbo et al. 2002, 2006; Jackson et al. 2008; Stickgold 2008 "
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    ABSTRACT: The function of sleep in birds is poorly understood, even though birds spend a large part of their lives sleeping. Sleep behaviour in passerine birds has not been looked at as extensively as that of nonpasserine birds. We looked at the sleep behaviour of three passerine birds occurring in southern Africa, namely the malachite sunbird, Nectarinia famosa, the Cape white-eye, Zosterops virens, and the fan-tailed widowbird, Euplectes axillaris. By using an infrared-sensitive camera, we recorded basic sleep behaviour, at various ambient temperatures, of all three species, such as sleep position and eye closure. We also investigated the incidence, or lack thereof, of unihemispheric sleep. Individuals of all three species spent most of the night asleep and woke up intermittently throughout the night, with no significant differences between temperatures. Cape white-eyes and malachite sunbirds showed an increase in back sleep and a decrease in front sleep at 5 °C. Little evidence of unihemispheric sleep was found, suggesting that it is more likely to occur in nonpasserines.
    Full-text · Article · Jan 2009 · Animal Behaviour
    • "The critical role that sleep (both REM and non-REM) plays in the consolidation of new information has been well-established in the literature (Stickgold, 2008; 2005, 2004, 2001; Rauchs et al., 2005; Rosanova & Ulrich, 2005; Clemens, Fabo, & Halasz, 2005; Gais, Molle, Helms &Born, 2002; Frackowiak et al. 2004; Steriade & Timofeev, 2003; Molle, Marshall, Gais, & Born, 2002; Kandel et al., 2000; Smith, 1985). Consolidation of information occurs only during sleep (e.g., Stickgold, 2005, 2004; Euston et al., 2007). "
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    ABSTRACT: This presentation will provide an overview of the clinical stages of sleep, from non-REM sleep to REM sleep. It will include three major segments: sleep and the role of dreaming in consolidating new learning; the role of sleep in mood regulation and cognitive functions; and sleep deprivation as a major cause of pre-mature aging. Recent findings from sleep research have shown that sleep plays a major role in working memory, general memory, executive functions, behavioral inhibition, and attention. It also plays an equally important role in the regulation of the neurotransmitters required for each stage of information processing, especially consolidation and retrieval (Stickgold, 2005; Nelson, 2005). Learning and memory circuits are reactivated and strengthened during both non-REM and REM sleep. Sleep is also thought to play a pivotal role in neuroplasticity, and different stages of learning require different phases of sleep (Hobson & Pace 2002; Stickgold, 2005).
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