Sleep and fatigue: Lessons from Antarctica

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Abstracts of SAN Meeting / Neuroscience Letters 500S (2011) e1–e54

100 ms leading to the REM. This sequence testifies to the emotional activation during REM sleep. In combination, the above EEG and MEG studies demonstrate very rich dynamics in time and brain space, which suggest that in NonREM sleep consciousness is not lost because of loss of wealth of information processing, but because of loss of brain specific connectivity needed for integration. doi:10.1016/j.neulet.2011.05.113 Segregation of function in space, time and frequency in awake state and sleep: Recent results and their possible relationship to Neurofeedback Andreas A. Ioannides Laboratory for Human Brain Dynamics, AAI Scientific Cultural Services Ltd., Cyprus Functional specialization, one of the few principles of modern neuroscience, rests on two pillars. Segregation of function is the first pillar and it is demonstrated by numerous fMRI studies, and supported by the parcellation of the brain into areas according to cytoarchitectonic and neurotransmitter receptor density criteria. The second pillar of functional specialization is the integration of activity in different areas giving rise to perception and consciousness. While the first pillar emphasizes static aspects of brain organization, the second emphasizes dynamics. Functional specialization offers many options as can be seen in the ensemble of single trial activations evoked by stimuli both at the neuron and regional levels in health and disease and involves a wide range of timescales. Events at the shorter timescales (∼ milliseconds) do not usually reach conscious awareness. For the longer timescales (minutes to hours) changes of state dominate. Correlates of functional specialization can be extracted over much of the different timescales through frequency analysis of mass electrical activity. This analysis reveals a remarkable frequency specificity that can be seen in the EEG changes across different sleep stages that happen automatically every evening or even in the more simple scenario of keeping our eyes open or closed. Our tomographic analysis of MEG signals during sleep has demonstrated that the frequency specificity has distinct spatial distribution in each sleep stage. This has been recently confirmed by other methods. Brain rhythms characterize different systems in the resting brain: the Default System, the Theory of Mind (ToM) system and what can be thought of as their opposite the attentional system. Each of these neural network is composed of distinct brain areas, it operates best in specific frequencies and often works antagonistically with others. In the end all networks must somehow cooperate for normal brain function to be possible. It is easy to see how undue dominance or weakness of one or other neuronal network might lead to problems. It is then plausible to consider addressing such problems through neurofeedback: by teaching the brain how to emphasize or de-emphasize activity in specific frequency bands captured by well-placed EEG electrodes. The development of methods for “real-time scanning” of the awake and especially sleeping brain offers powerful, yet admittedly demanding ways of grounding neurofeedback methods to basic neurophysiology through detailed exploration of the role of brain rhythms.

Sleep and fatigue: Lessons from Antarctica Pattyn Nathalie 1,2 , Cortoos Aisha 2,3 , Olivier Mairesse 2 , Sandra Pirrera 1 , De Valck Elke 1 , Xavier Neyt 2 , Pierre-Franc¸ois Migeotte 2 , Cluydts Raymond 1 1 Dept. of Biological Psychology, Vrije Universiteit Brussel, Brussels, Belgium 2 VIPER, Royal Military Academy, Belgium 3 Sleep Unit, UZ Brussel, Belgium The present investigation was conducted during two Antarctic summer expeditions, the BELARE (Belgian Antarctic Research Expedition) campaigns 2007–2008 and 2008–2009. 8 subjects were investigated in the first expedition. 22 subjects participated during the second campaign. Data were collected every 2 weeks for each subject in the first campaign, once or twice per subject in the second campaign. These included 48 h actigraphy, one night polysomnography, morning and evening Profile of Mood States and Karolinska Sleepiness Scale, morning Psychomotor Vigilance Test. Morning and evening saliva samples were taken to determine melatonin levels. Circadian rhythms profiles were determined with one 18 h cortisol sampling. First year data showed poor sleep efficiency and high sleep fragmentation, in concordance with participants’ subjective evaluations. Furthermore, there was a strong correlation between sleep efficiency and active energy expenditure (Pearson’s r = 0.63; p = 0.015), as well as a strong relationship between active energy expenditure and sleep fractionation. Second year polysomnography results showed, in addition to high sleep fragmentation, both subjective and objective, a dramatic decrease in slow wave sleep and an increase in REM sleep. Cortisol rhythmicity was preserved, and remarkably synchronized among participants. Melatonin secretion however, showed a severe phase delay. There was a severe decrease in performance, as assessed through the PVT, but no effect whatsoever on mood. Results from the first campaign confirmed both our hypotheses, namely the lower sleep quality (lower efficiency and higher fractionation) during the expedition and the relationship between sleep quality and active energy expenditure. Data from the second campaign showed a desynchronisation between cortisol and melatonin secretion, which is hypothesized to explain the decrease in slow wave sleep, a severe effect on performance, compatible with the effect of sleep deprivation, and no effect on mood, which is hypothesized to be ascribable to the effect of continuous bright light exposure. These findings, and mainly the dissociation between fatigue and sleepiness as well as the effect of exercise, are discussed in the frame of potential countermeasures for fatigue. doi:10.1016/j.neulet.2011.05.115 The concept of cortical de-arousal in insomnia Cortoos Aisha 1,2 , Pattyn Nathalie 2,3 , Mairesse Olivier 2 , Neyt Xavier 2 , Migeotte Pierre-Franc¸ois 2 , De Weerdt Sonia 1 , Vincken Walter 1 , Cluydts Raymond 3 1 Sleep Unit, Dept. of Pneumology, Universitair Ziekenhuis Brussel, Brussels, Belgium 2 VIPER, Royal Military Academy, Belgium 3 Dept. of Experimental and Applied Psychology, Vrije Universiteit Brussel, Brussels, Belgium

doi:10.1016/j.neulet.2011.05.114 Introduction: The neurocognitive perspective on insomnia posits that conditioned hyperarousal is reflected by increased high frequency EEG activity resulting in impairment of information processing, and, as such, interfering with normal sleep onset and – maintenance processes. The presence of cortical hyperarousal can be evaluated in different ways going from the analysis of the electroencephalogram (EEG) during wake as well as sleep time, specific