401
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Vandewalle G, Maquet P, Dijk DJ. Light as a modulator of cognitive brain function. Trends Cogn Sci 2009; 13:429-38. [PMID: 19748817 DOI: 10.1016/j.tics.2009.07.004] [Citation(s) in RCA: 268] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 07/30/2009] [Accepted: 07/30/2009] [Indexed: 11/20/2022]
Abstract
Humans are a diurnal species usually exposed to light while engaged in cognitive tasks. Light not only guides performance on these tasks through vision but also exerts non-visual effects that are mediated in part by recently discovered retinal ganglion cells maximally sensitive to blue light. We review recent neuroimaging studies which demonstrate that the wavelength, duration and intensity of light exposure modulate brain responses to (non-visual) cognitive tasks. These responses to light are initially observed in alertness-related subcortical structures (hypothalamus, brainstem, thalamus) and limbic areas (amygdala and hippocampus), followed by modulations of activity in cortical areas, which can ultimately affect behaviour. Light emerges as an important modulator of brain function and cognition.
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Affiliation(s)
- Gilles Vandewalle
- Cyclotron Research Centre, University of Liège, 8 Allée du 6 Août, Bâtiment B30, B-4000 Liège, Belgium.
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402
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Tiplady B, Oshinowo B, Thomson J, Drummond GB. Alcohol and cognitive function: assessment in everyday life and laboratory settings using mobile phones. Alcohol Clin Exp Res 2009; 33:2094-102. [PMID: 19740132 DOI: 10.1111/j.1530-0277.2009.01049.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Mobile phone (cellphone) technology makes it practicable to assess cognitive function in a natural setting. We assessed this method and compared impairment of performance due to alcohol in everyday life with measurements made in the laboratory. METHODS Thirty-eight volunteers (20 male, aged 18-54 years) took part in the everyday study, completing assessments twice a day for 14 days following requests sent by text messages to the mobile phone. Twenty-six of them (12 male, aged 19-54) took part in a subsequent two-period crossover lab study comparing alcohol with no alcohol (placebo). RESULTS Everyday entries with 5 or more units of alcohol consumed in the past 6 hours (inferred mean blood alcohol concentration 95 ml/100 ml) showed higher scores for errors in tests of attention and working memory compared with entries with no alcohol consumed that day. Response times were impaired for only 1 test, sustained attention to response. The laboratory comparison of alcohol (mean blood alcohol concentration 124 mg/100 ml) with placebo showed impairment to both reaction time and error scores for all tests. A similar degree of subjective drunkenness was reported in both settings. CONCLUSIONS We found that mobile phones allowed practical research on cognitive performance in an everyday life setting. Alcohol impaired function in both laboratory and everyday life settings at relevant doses of alcohol.
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Affiliation(s)
- Brian Tiplady
- Department of Anaesthesia, Pain, and Critical Care Medicine, University of Edinburgh, Edinburgh, UK.
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403
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Tamm AS, Lagerquist O, Ley AL, Collins DF. Chronotype influences diurnal variations in the excitability of the human motor cortex and the ability to generate torque during a maximum voluntary contraction. J Biol Rhythms 2009; 24:211-24. [PMID: 19465698 DOI: 10.1177/0748730409334135] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ability to generate torque during a maximum voluntary contraction (MVC) changes over the day. The present experiments were designed to determine the influence of an individual's chronotype on this diurnal rhythm and on cortical, spinal, and peripheral mechanisms that may be related to torque production. After completing a questionnaire to determine chronotype, 18 subjects (9 morning people, 9 evening people) participated in 4 data collection sessions (at 09:00, 13:00, 17:00, and 21:00) over 1 day. We used magnetic stimulation of the cortex, electrical stimulation of the tibial nerve, electromyographic (EMG) recordings of muscle activity, and isometric torque measurements to evaluate the excitability of the motor cortex, the spinal cord, and the torque-generating capacity of the triceps surae (TS) muscles. We found that for morning people, cortical excitability was highest at 09:00, spinal excitability was highest at 21:00, and there were no significant differences in TS EMG or torque produced during MVCs over the day. In contrast, evening people showed parallel increases in cortical and spinal excitability over the day, and these were associated with increased TS EMG and MVC torque. There were no differences at the level of the muscle over the day between morning and evening people. We propose that the simultaneous increases in cortical and spinal excitability increased central nervous system drive to the muscles of evening people, thus increasing torque production over the day. These differences in cortical excitability and performance of a motor task between morning and evening people have implications for maximizing human performance and highlight the influence of chronotype on an individual's diurnal rhythms.
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Affiliation(s)
- Alexander S Tamm
- Human Neurophysiology Laboratory, Faculty of Physical Education and Recreation, Centre for Neuroscience, 6-40 General Services Building, University of Alberta, Edmonton, AB, Canada
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404
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Edgar CJ, Pace-Schott EF, Wesnes KA. Approaches to measuring the effects of wake-promoting drugs: a focus on cognitive function. Hum Psychopharmacol 2009; 24:371-89. [PMID: 19565524 PMCID: PMC2747813 DOI: 10.1002/hup.1034] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVES In clinical drug development, wakefulness and wake-promotion may be assessed by a large number of scales and questionnaires. Objective assessment of wakefulness is most commonly made using sleep latency/maintenance of wakefulness tests, polysomnography and/or behavioral measures. The purpose of the present review is to highlight the degree of overlap in the assessment of wakefulness and cognition, with consideration of assessment techniques and the underlying neurobiology of both concepts. DESIGN Reviews of four key areas were conducted: commonly used techniques in the assessment of wakefulness; neurobiology of sleep/wake and cognition; targets of wake promoting and/or cognition enhancing drugs; and ongoing clinical trials investigating wake promoting effects. RESULTS There is clear overlap between the assessment of wakefulness and cognition. There are common techniques which may be used to assess both concepts; aspects of the neurobiology of both concepts may be closely related; and wake-promoting drugs may have nootropic properties (and vice versa). Clinical trials of wake-promoting drugs often, though not routinely, assess aspects of cognition. CONCLUSIONS Routine and broad assessment of cognition in the development of wake-promoting drugs may reveal important nootropic effects, which are not secondary to alertness/wakefulness, whilst existing cognitive enhancers may have underexplored or unknown wake promoting properties.
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Affiliation(s)
| | - Edward F. Pace-Schott
- Department of Psychiatry, Center for Sleep and Cognition, Harvard Medical School, Beth Israel-Deaconess Medical Center, Boston, Massachusetts, USA
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405
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BRATZKE DANIEL, ROLKE BETTINA, STEINBORN MICHAELB, ULRICH ROLF. The effect of 40 h constant wakefulness on task-switching efficiency. J Sleep Res 2009; 18:167-72. [DOI: 10.1111/j.1365-2869.2008.00729.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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406
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The role of sleep in false memory formation. Neurobiol Learn Mem 2009; 92:327-34. [PMID: 19348959 DOI: 10.1016/j.nlm.2009.03.007] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 03/26/2009] [Accepted: 03/31/2009] [Indexed: 11/22/2022]
Abstract
Memories are not stored as exact copies of our experiences. As a result, remembering is subject not only to memory failure, but to inaccuracies and distortions as well. Although such distortions are often retained or even enhanced over time, sleep's contribution to the development of false memories is unknown. Here, we report that a night of sleep increases both veridical and false recall in the Deese-Roediger-McDermott (DRM) paradigm, compared to an equivalent period of daytime wakefulness. But while veridical memory deteriorates across both wake and sleep, false memories are preferentially preserved by sleep, actually showing a non-significant improvement. The same selectivity of false over veridical memories was observed in a follow-up nap study. Unlike previous studies implicating deep, slow-wave sleep (SWS) in declarative memory consolidation, here veridical recall correlated with decreased SWS, a finding that was observed in both the overnight and nap studies. These findings lead to two counterintuitive conclusions - that under certain circumstances sleep can promote false memories over veridical ones, and SWS can be associated with impairment rather than facilitation of declarative memory consolidation. While these effects produce memories that are less accurate after sleep, these memories may, in the end, be more useful.
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407
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Popović N, Baño-Otálora B, Rol MA, Caballero-Bleda M, Madrid JA, Popović M. Aging and time-of-day effects on anxiety in female Octodon degus. Behav Brain Res 2009; 200:117-21. [PMID: 19162080 DOI: 10.1016/j.bbr.2009.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 12/27/2008] [Accepted: 01/03/2009] [Indexed: 11/18/2022]
Abstract
Animal models of anxiety have usually employed nocturnal species (e.g. rats and mice), and the tests used have been almost exclusively performed during the diurnal phase (lights on). Here, for the first time, we tested anxiety in a diurnal rodent, Octodon degus, according to its age (23 versus 40 months of age) and the time of the day. We employed three anxiety tests: object recognition, open field and light-dark tests, which were applied in the morning, at mid-day and in the late afternoon, respectively. Adult animals spent more time exploring a new object than aged animals. Nevertheless, there were no differences in the frequency of object exploration or in the latency to the first object approach between the groups. In the open field test, adult animals spent more time exploring (ambulation and rearing) than aged ones. Although both groups exhibited similar frequencies in transition from the dark to the light box in the light-dark test, adult animals spent significantly more time in the light, and expressed less anxiety when making the decision to cross over from the dark into the light area. In conclusion, there were no differences in anxiety between adult and aged animals in the morning session, although adult animals were more attentive when exploring a new object. However, in the mid-day and afternoon testing sessions, aged animals were more anxious than adults.
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Affiliation(s)
- Natalija Popović
- Chronobiology Laboratory, Department of Physiology, Faculty of Biology, University of Murcia, 30100 Murcia, Spain.
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408
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Abstract
Endogenous biological clocks are widespread regulators of behavior and physiology, allowing for a more efficient allocation of efforts and resources over the course of a day. The extent that different processes are regulated by circadian oscillators, however, is not fully understood. We investigated the role of the circadian clock on short-term associative memory formation using a negatively reinforced olfactory-learning paradigm in Drosophila melanogaster. We found that memory formation was regulated in a circadian manner. The peak performance in short-term memory (STM) occurred during the early subjective night with a twofold performance amplitude after a single pairing of conditioned and unconditioned stimuli. This rhythm in memory is eliminated in both timeless and period mutants and is absent during constant light conditions. Circadian gating of sensory perception does not appear to underlie the rhythm in short-term memory as evidenced by the nonrhythmic shock avoidance and olfactory avoidance behaviors. Moreover, central brain oscillators appear to be responsible for the modulation as cryptochrome mutants, in which the antennal circadian oscillators are nonfunctional, demonstrate robust circadian rhythms in short-term memory. Together these data suggest that central, rather than peripheral, circadian oscillators modulate the formation of short-term associative memory and not the perception of the stimuli.
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Affiliation(s)
- Lisa C Lyons
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204, USA.
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409
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Diekelmann S, Landolt HP, Lahl O, Born J, Wagner U. Sleep loss produces false memories. PLoS One 2008; 3:e3512. [PMID: 18946511 PMCID: PMC2567433 DOI: 10.1371/journal.pone.0003512] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 10/01/2008] [Indexed: 11/19/2022] Open
Abstract
People sometimes claim with high confidence to remember events that in fact never happened, typically due to strong semantic associations with actually encoded events. Sleep is known to provide optimal neurobiological conditions for consolidation of memories for long-term storage, whereas sleep deprivation acutely impairs retrieval of stored memories. Here, focusing on the role of sleep-related memory processes, we tested whether false memories can be created (a) as enduring memory representations due to a consolidation-associated reorganization of new memory representations during post-learning sleep and/or (b) as an acute retrieval-related phenomenon induced by sleep deprivation at memory testing. According to the Deese, Roediger, McDermott (DRM) false memory paradigm, subjects learned lists of semantically associated words (e.g., "night", "dark", "coal",...), lacking the strongest common associate or theme word (here: "black"). Subjects either slept or stayed awake immediately after learning, and they were either sleep deprived or not at recognition testing 9, 33, or 44 hours after learning. Sleep deprivation at retrieval, but not sleep following learning, critically enhanced false memories of theme words. This effect was abolished by caffeine administration prior to retrieval, indicating that adenosinergic mechanisms can contribute to the generation of false memories associated with sleep loss.
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Affiliation(s)
| | - Hans-Peter Landolt
- Institute of Pharmacology and Toxicology, and Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Olaf Lahl
- Institute of Experimental Psychology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Jan Born
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
| | - Ullrich Wagner
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
- Department of Neuroscience, University Medical School, University of Geneva, Geneva, Switzerland
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410
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Chronotype and time-of-day influences on the alerting, orienting, and executive components of attention. Exp Brain Res 2008; 192:189-98. [DOI: 10.1007/s00221-008-1567-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Accepted: 09/02/2008] [Indexed: 10/21/2022]
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411
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Abstract
In the course of evolution, mechanisms have evolved to anticipate the timing of regularly occurring events. These mechanisms are encompassed in a circadian timing system that include a master clock localized to the suprachiasmatic nucleus of the hypothalamus and "slave" oscillators distributed throughout the body. This system serves multiple functions so as to ensure that various physiological processes occur at optimal and nonoverlapping times, to synchronize our activities to local environmental time, and to permit changes required to respond to new environmental circumstances. We suggest that a generalized concept of arousal (which includes alterations in responsiveness to homeostatic pressures, sensory stimuli and emotional reactivity, and to changes in motor activity) serves as a rubric in which to explore the multiple ways in which the circadian system modulates behavior.
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Affiliation(s)
- Rae Silver
- Department of Psychology, Columbia University, New York, New York 10027, USA.
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