Les données épidémiologiques et les pourcentages de consommation de médicaments ne permettent pas de faire un lien de causalité entre un produit donné et une éventuelle détérioration de la conduite. Des études sont aujourd'hui menées pour tenter d'appréhender les facteurs influençant les variations du niveau d'éveil dans le domaine de la conduite. Nos expériences s'intègrent dans ce cadre et en particulier sur l'influence de sédatifs administrés à dose thérapeutique par une prescription médicale standard. Nous avons mené deux expériences de conduite sur simulateur avec différents groupes de sujets sains (jeunes, âgés), après une nuit complète de sommeil. Nous avons réalisé des mesures subjectives (QCM) et objectives (analyse spectrale de l'EEG) de l'éveil, des mesures de vigilance et d'attention. Dans chaque expérience, les psychotropes étudiés sont administrés seuls ou combinés et comparés à un placebo. Nos résultats sur l'effet dose d'un analgésique ne montrent aucun effet de ce sédatif sur la performance de conduite, sur l'éveil subjectif et la vigilance chez des sujets jeunes et sains. Les résultats sur l'effet combiné d'un analgésique et d'un hypnotique ne suggèrent aucune interaction entre ces deux produits chez des sujets âgés et sains, ils n'indiquent aucun effet sur l'éveil objectif ni subjectif, ni sur la vigilance et l'attention. Cependant, nous observons sur la performance de conduite des effets indépendants de chacun de ces psychotropes.

<p>Evolution is fuelled by independent reproduction events. Yet, the offspring of at least three percent of all bird species postpone dispersal and forego independent reproduction. The Siberian jay, <i>Perisoreus infaustus, </i>is such a species where some<i> </i>offspring are philopatric and remain in their natal territory for up to three years, forming family groups. The main finding of this thesis is that nepotistic anti-predator behaviour displayed by parents provided philopatric offspring benefits, which could be an incentive to stay and forego independent reproduction. Predation, (hawks - 80 % and owls - 15% of deaths observed) is the main cause of mortality. Parents increased their vigilance nepotistically; they were more vigilant against surprise predator attacks, and gave alarm calls when attacked when feeding together with offspring. However, the two parents differed in their behaviour. Mothers gave calls only when together with their offspring, while males also warned unrelated immigrants. Sitting predators were approached and mobbed more intensely by parents in the presence of philopatric offspring. The vocalisation of Siberian jays provides information about predation risk. Specific calls are given for hawks and owls, and calls also varied with hawk behaviour. The nepotistic anti-predator behaviour of parents is a benefit, which the offspring can gain only “at home”, and such behaviour appears to promote offspring to forego dispersal and independent reproduction. This was confirmed in an experimental manipulation; philopatric offspring dispersed when fathers were removed and replaced by a despotic, immigrant stepfather. From a life-history perspective, parents have an incentive to protect their reproductive investment. Nepotistic anti-predator behaviour create a safe haven in the natal territory for philopatric offspring and provides direct fitness benefits. Without such direct fitness benefits offspring may disperse and wait for a breeding opening elsewhere. </p>

Evolution is fuelled by independent reproduction events. Yet, the offspring of at least three percent of all bird species postpone dispersal and forego independent reproduction. The Siberian jay, Perisoreus infaustus, is such a species where some offspring are philopatric and remain in their natal territory for up to three years, forming family groups. The main finding of this thesis is that nepotistic anti-predator behaviour displayed by parents provided philopatric offspring benefits, which could be an incentive to stay and forego independent reproduction. Predation, (hawks - 80 % and owls - 15% of deaths observed) is the main cause of mortality. Parents increased their vigilance nepotistically; they were more vigilant against surprise predator attacks, and gave alarm calls when attacked when feeding together with offspring. However, the two parents differed in their behaviour. Mothers gave calls only when together with their offspring, while males also warned unrelated immigrants. Sitting predators were approached and mobbed more intensely by parents in the presence of philopatric offspring. The vocalisation of Siberian jays provides information about predation risk. Specific calls are given for hawks and owls, and calls also varied with hawk behaviour. The nepotistic anti-predator behaviour of parents is a benefit, which the offspring can gain only “at home”, and such behaviour appears to promote offspring to forego dispersal and independent reproduction. This was confirmed in an experimental manipulation; philopatric offspring dispersed when fathers were removed and replaced by a despotic, immigrant stepfather. From a life-history perspective, parents have an incentive to protect their reproductive investment. Nepotistic anti-predator behaviour create a safe haven in the natal territory for philopatric offspring and provides direct fitness benefits. Without such direct fitness benefits offspring may disperse and wait for a breeding opening elsewhere.

Regular use of illegal drugs is suspected to cause cognitive impairments. Two substances have received heightened attention: 3,4-methylenedioxymethamphetamine (MDMA or ‘ecstasy’) and δ-9-tetrahydrocannabinol (THC or ‘cannabis’). Preclinical evidence, as well as human studies examining regular ecstasy consumers, indicated that ecstasy use may have negative effects on learning, verbal memory and complex attentional functions. Cannabis has also been linked to symptoms of inattention and deficits in learning and memory. Most of the published studies in this field of research recruited participants by means of newspaper advertisements or by using word-of-mouth strategies. Because participants were usually aware that their drug use was critical to the research design, this awareness may have caused selection bias or created expectation effects. Focussing on attention and memory, this study aimed to assess cognitive functioning in a community-based representative sample that was derived from a large-scale epidemiological study. Available data concerning drug use history allowed sampling of subjects with varying degrees of lifetime drug experiences. Cognitive functioning was examined in 284 young participants, between 22 and 34 years. In general, their lifetime drug experience was moderate. Participants completed a neuropsychological test battery, including measures for verbal learning, memory and various attentional functions. Linear regression analysis was performed to investigate the relationship between cognitive functioning and lifetime experience of drug use. Ecstasy and cannabis use were significantly related to poorer episodic memory function in a dose-related manner. For attentional measures, decrements of small effect sizes were found. Error measures in tonic and phasic alertness tasks, selective attention task and vigilance showed small but significant effects, suggesting a stronger tendency to experience lapses of attention. No indication for differences in reaction time was found. The results are consistent with decrements of memory and attentional performance described in previous studies. These effects are relatively small; however, it must be kept in mind that this study focussed on assessing young adults with moderate drug use from a population-based study.

This thesis consisted of experiments designed to explore the construct of attention and investigate the disruptive effects of psychotomimetics, with a specific focus on NMDA antagonists. Phencyclidine (PCP) was administered through a variety of treatment regimens in order to to determine the ability of inducing cognitive-specific disruptions in attentional functioning. The hypothesis that sub-chronic exposure to PCP would result in persistent attentional impairment was tested, using the 5-choice serial reaction time task (5-CSRTT). The 5-CSRTT assesses not only visuospatial attention, but also components of impulsivity, compulsivity, speed of processing and motivation. It was determined that an additional task-related intervention that increased the attentional load was required to elucidate attentional impairment following sub-chronic PCP treatment. The ability of rats to perform the modified version of the 5-CSRTT, known as the 5-choice continuous performance test (5C-CPT), was investigated. The 5C-CPT was implemented to provide a task that may have greater analogy to the human CPT, than the original 5-CSRTT. The consequence of dopaminergic D1 system activation was investigated. It was revealed that D1 partial agonism improved attentional performance in a baseline-dependent manner. Following successful acquisition of the task, it was shown that repeated PCP treatment induced cognitive disruption that was cognitive-specific, and not confounded by generalised response disruption. Furthermore, a partial attenuation of the PCP-induced performance disruption was achieved following administration of the D1 partial agonist, SKF 38393. Moreover, sub-chronic PCP treatment was shown to impair 5C-CPT performance in the drug-free state. However, an additional challenge that further increased the attentional load was needed to elucidate a performance deficit. This highlighted that sustained attention/vigilance is sensitive to persistent impairment following sub-chronic PCP administration in a manner consistent with deficits observed in schizophrenia patients. This prompted the investigation that tested the hypothesis that sub-chronic PCP treatment could induce enduring structural deficits in regions associated with attentional performance. Magnetic resonance imaging (MRI) was conducted, in conjunction with 5-CSRTT and pre-pulse inhibition (PPI). It was revealed that sub-chronic PCP treatment resulted in morphological brain abnormalities in brain regions associated with 5-CSRTT performance. This was coupled with deficits in sustained attentional performance following an increase in attentional load, yet PPI was unaffected. Taken together, these findings suggested sub-chronic PCP treatment impairs attentional functionality, an effect that dissociates between effortful and passive attentional processes.

À tout âge, l’exercice physique peut être bénéfique au fonctionnement cognitif. Étant quotidiennement confrontés à des situations d’apprentissage, l’enfant et l’adolescent constituent une population particulièrement susceptible de profiter de ces bienfaits. Cependant, il importe de préciser et d’étudier les facteurs qui influencent la relation entre l’exercice physique et la cognition. L’objectif général de cette thèse était d’examiner, à l’aide de mesures électrophysiologiques, les effets aigus et chroniques de l’exercice physique sur les mécanismes neurophysiologiques du fonctionnement cognitif de l’enfant. Une première étude a apprécié la durée des effets aigus de l’exercice physique. Les résultats de ces travaux suggèrent qu’une séance ponctuelle d’exercice physique augmente la vigilance pendant au moins 30 min. Toujours dans un contexte d’effets aigus de l’exercice, l’impact de la demande cognitive de la tâche et de l’âge ont été examinés dans une seconde étude. Les résultats ne révèlent aucune interaction avec l’âge, cependant ils indiquent une spécificité pour les processus plus complexes du traitement de l’information. Enfin, une troisième étude a évalué l’effet de l’exercice physique chronique dans le cadre d’un programme d’activités physiques de 12 semaines. Aucun changement n’a été observé quant à l’aptitude cardiovasculaire ou la performance cognitive suite au programme. Une condition physique initialement élevée des participants pourrait expliquer ce résultat. En résumé, peu importe la condition physique de l’enfant, un exercice physique aigu d’intensité moyenne est bénéfique à la vigilance et à certains aspects du traitement cognitif de l’information. Les effets observés semblent suffisamment durables pour avoir un impact positif sur l’apprentissage en classe après une récréation ou un cours d’éducation physique. / Exercise can be beneficial for cognitive functioning throughout lifespan. Children and adolescents may particularly benefit from the effects of exercise on cognition as they continually face learning situations. However, it is important to identify and to study the factors that influence the relationship between exercise and cognition. The general objective of this thesis was to examine, with electrophysiological measures, the acute and chronic effects of exercise on electrophysiological mechanisms of cognitive functioning in children. A first study appreciated the duration of the acute effect of a single session of exercise. The results suggested that a single session of exercise increases vigilance for at least 30 min. Still in a context of acute exercise, the impact of the cognitive demand of the task and age were examined in a second study. Although the results did not reveal any significant interaction with age, they indicated specific benefits for the more complex cognitive processes compare to more automatic processes. Finally, a third study evaluated the effect of a 12-week program of physical activity. Following the 12-week program, no change was observed neither for the cardiovascular function nor the cognitive performance. The fact that participants already demonstrated a high level of fitness at baseline may explain this result. In conclusion, regardless of a child’s fitness level, it appears that an exercise of moderate intensity improves vigilance and some aspects of information processing. The observed effects appear to last long enough to have a positive impact on classroom learning after a recess or a physical education class.

Le travail de nuit est associé avec plusieurs problèmes de santé. Le désalignement entre la phase circadienne et le cycle éveil-sommeil cause une désynchronie interne considérée comme la principale source de ces problèmes. L’ajustement circadien au travail de nuit est proposé comme contremesure. Normalement, l’ajustement circadien complet n’est pas recommandé puisqu’il engendre un désalignement circadien lors du retour à l’horaire de jour, causant des changements de phase répétés et la désynchronie interne. L’ajustement circadien partiel est alors proposé comme compromis afin de stabiliser les rythmes circadiens des travailleurs de nuit. Cependant, l’ampleur de l’ajustement circadien partiel nécessaire à l’amélioration du sommeil et de la vigilance demeure vague. Les ajustements partiels obtenus par délai ou avance de phase sont quantifiés non seulement par la phase du début de la sécrétion de mélatonine en lumière tamisée, mais également par le recoupement de l’épisode de sécrétion de mélatonine avec les périodes d’éveil et de sommeil. Les effets sur le sommeil et la vigilance d’un petit ajustement circadien partiel significatifs sont investigués dans une simulation de travail de nuit en laboratoire pour déterminer leurs implications cliniques. Les effets modestes suggèrent qu’un petit délai de phase peut réduire l’accumulation de la dette de sommeil, alors que l’avance de phase améliore subjectivement la vigilance et l’humeur nocturne. L’ampleur absolue du changement de phase est associée à une amélioration subjective de la vigilance et de l’humeur nocturne. Des études en milieux de travail permettraient de déterminer si ces stratégies sont applicables et bénéfiques aux travailleurs de nuit. / Night work is associated with many short and long term health problems. Misalignment between the circadian phase and the sleep-wake schedule causes a state of internal desynchrony considered as the main cause of these health problems. Circadian adjustment to night work is proposed as a countermeasure. Usually, complete circadian adjustment is not recommended because night workers experience circadian misalignment when returning on a day-active schedule, causing repeated circadian phase shifts and internal desynchrony. Therefore, partial circadian realignment was proposed as a compromise to stabilize circadian rhythms in night workers. However, the extent of partial circadian adjustment necessary to improve sleep and vigilance quality is still unclear. Here, partial adjustments obtained by phase delay or advance were quantified not only by the phase shift of dim light salivary melatonin onset, but also by the overlap of the melatonin production episode with the sleep-wake cycle during simulated night work. The effects of small but statistically significant partial circadian adjustments on sleep and vigilance quality were assessed in a laboratory simulation of night work to determine their clinical significance. Effects on daytime sleep and night-time vigilance quality were modest. They suggest that even small phase delays may decrease the accumulation of sleep debt, whereas the advance strategy improves subjective night work alertness and mood. Absolute phase shifts, by advance or delay, were associated with improved subjective night work alertness and mood. Field studies are needed, to determine whether these strategies can be adapted to real-life situations and provide effective support to night workers.

輪班工作者除了睡眠片段化、睡眠品質降低等困擾外，工作時間的嗜睡與警醒度下降亦是常見問題，這些影響都可能跟輪班造成的內在晝夜節律與輪班工作時間的不一致有關。根據Minors & Waterhouse (1983)提出的定錨睡眠的概念，每天若能有四個小時在固定時間的睡眠，會有穩定內在晝夜節律、減少位移的效果，然而過去研究未曾探討定錨睡眠應用在輪班工作者的效果。因此，本研究的目的在於以模擬輪班的方式，比較採用定錨睡眠者與非定錨睡眠者在模擬輪班工作中的主觀嗜睡度、心理動作警覺度，以及睡眠指標，以探討定錨睡眠對於輪班工作者的睡眠與警覺度的影響，以期有助於輪班工作中的適應。 本研究採混合實驗設計，招募睡眠品質良好的受試者，並排除極端夜貓型或極端早晨型晝夜節律型態者，共包含20名受試者、依據性別配對隨機分派至定錨睡眠與無定錨睡眠組（各7名女性、3名男性，平均年齡24歲）。受試者需進行11天的模擬輪班，進行白班與大夜班的輪班；班表為：2天白班-1天休假-2天大夜班-1天休假-2天白班-1天休假-2天大夜班，受試者在實驗期間均配合配戴活動記錄儀與填寫睡眠日誌，並在第二次輪值的工作時間測量心理動作警覺作業（psychomotor vigilance task，PVT）與史丹福嗜睡度量表（Stanford Sleepiness Scale，SSS）。研究結果以三因子及雙因子變異數分析進行統計考驗。 研究結果發現在PVT的反應時間中位數與疏漏次數上，採用定錨睡眠者在白班至大夜班所增加的反應時間與疏漏次數低於非採用定錨睡眠者，且採用定錨睡眠者在工作時有較低的主觀嗜睡度、持平的主觀警醒度；在睡眠指標上，定錨睡眠組入睡後醒覺時數較短、夜班的主觀睡眠品質較佳。整體來說，研究結果顯示採用定錨睡眠能增進在工作中的心理動作警覺度、降低主觀嗜睡度，並促進睡眠的穩定度及夜班主觀睡眠品質，提供定錨睡眠運用在實際的輪班工作場域的初步證據。 / Sleep fragmentation, poor sleep quality, as well as sleepiness and decreased alertness at work are all common problems in shift workers. It is assumed that these problems are associated with the dyssynchronization of endogenous circadian rhythms and shift-work schedule. According to the concept of anchor sleep proposed by Minors & Waterhouse (1983), consistent sleep for few consecutive days can stabilize endogenous circadian rhythm and prevent the phase shift. However, previous studies have not investigate the effect of anchor sleep in shift workers . The current study used an experiment-manipulated shift work schedule to explore the effects of anchor sleep on sleep, sleepiness and psychomotor vigilance at work in a simulated shift work, in order to evaluate the possibility of applying anchor sleep in the assistance of adaption to shift work. Twenty participants with good sleep quality, intermediate types of morning-eveningness, were divided according to gender and randomly assigned to an anchor-group and a non-anchor-sleep control group (7 females and 3 males in each group, mean age 24). They were required to follow an eleven-day schedule that simulate the schedule of shift work. The subjects were required to wear actigraphy and keep sleep logs throughout the experimental period and their psychomotor vigilance and subjective sleepiness at the second work shifts were measured with psychomotor vigilance task (PVT) and Stanford Sleepiness Scale (SSS). The data was analyzed using three-way and two-way ANOVA. The data showed that PVT median reaction time and the number of lapses increased less from day-shift to night-shift in anchor sleeper, the anchor sleeper also had lower sleepiness, and more steady subjective alertness during the working time. Also, they had better subjective sleep quality in night-shift and shorter wake after sleep onset time than the control subjects. The findings of the current study suggest that anchor sleep can reduce the deterioration of subjective sleepiness and vigilance at work in shift workers, and maintain the sleep quality in night-shift. It provides preliminary evidence that support the use of anchor sleep in the assistance of the adjustment of shift work.

Diss. Tampereen teknillinen korkeakoulu, 2006. / Myös verkkojulkaisuna.

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