Le sommeil joue un rôle important dans la consolidation de la mémoire. Les expériences nouvellement acquises à l’éveil sont réactivées spontanément durant le sommeil, un processus qui aiderait à consolider et intégrer la mémoire à plus long terme. Il a été suggéré que ces réactivations de mémoire se reflétaient, du moins partiellement, dans le contenu des rêves et que les rêves pouvaient jouer un rôle actif dans la consolidation de la mémoire. L'objectif général de cette thèse de doctorat est ainsi d'évaluer si et comment le rêve est impliqué dans le traitement de la mémoire épisodique et procédurale en utilisant de nouvelles technologies et approches expérimentales pour étudier ces relations. La première étude de cette thèse visait à influencer les réactivations de mémoire durant le sommeil afin de clarifier leurs liens avec les rêves et la mémoire procédurale. Nous avons stimulé ces réactivations de mémoire en réexposant des participants, durant leur sommeil, à un stimulus sonore préalablement associé à un apprentissage moteur, une approche nommée « targeted memory reactivation » (TMR). Nous montrons que la TMR, lorsqu’appliquée en stade de sommeil paradoxal, permet d’améliorer l’apprentissage d’une tâche motrice complexe, soit apprendre à « voler » en réalité virtuelle. De plus, le fait de rêver à des éléments kinesthésiques de la tâche motrice en sommeil paradoxal, mais pas en sommeil lent léger, est associé à une meilleure amélioration à cette tâche (article I). Ces résultats appuient les modèles suggérant que le sommeil paradoxal joue un rôle important dans la consolidation de la mémoire procédurale complexe et suggèrent en outre que la simulation de sensations sensorimotrices dans les rêves pourrait contribuer à ce rôle. Bien que la TMR n’ait pas eu d’impact direct sur les rêves, nous montrons qu’elle peut influencer le décours temporel des incorporations de mémoire dans les rêves sur plusieurs jours. La TMR a amplifié les incorporations tardives de la tâche, soit 1-2 jours plus tard lorsqu’appliquée en sommeil paradoxal, et 5-6 jours plus tard lorsqu’appliquée en sommeil lent profond (article II). Nous suggérons que ces effets à plus long terme pourraient être dus à un mécanisme de marquage (tagging) des traces de mémoire, initiant ou amplifiant leur traitement subséquent au cours de plusieurs nuits de sommeil. De plus, nous montrons que notre expérience immersive en réalité virtuelle a augmenté l’incorporation de sensations de vol dans les rêves, particulièrement la nuit suivant l’exposition à celle-ci (article III). Nous identifions certains facteurs individuels qui sont associés à une plus grande incorporation de la tâche dans les rêves, tels que le fait d’avoir déjà eu des rêves de vols ou des rêves lucides. Un examen plus approfondi des rêves pendant 10 jours suivants l'expérience de réalité virtuelle montre que les sensations de vol sont progressivement décontextualisées du contexte de vol original au fil du temps. Les rêves de vol après l’expérience en réalité virtuelle avaient également des niveaux de contrôle et d'intensité émotionnelle plus élevés que ceux ayant eu lieu avant l’expérience. L'induction de rêves de vol nous a permis de faire une analyse qualitative approfondie sur ceux-ci, menant à une nouvelle proposition de la manière dont les sensations de vol, ou les sensations de mouvement de manière plus générale, peuvent survenir dans les rêves. Ces résultats pourraient à leur tour faciliter le développement de technologies pour mieux influencer et étudier les rêves. Une deuxième étude visait à évaluer quand et comment une source de mémoire épisodique commune à tous les participant – visiter le laboratoire de sommeil – est incorporé dans les rêves. Les résultats montrent que près du tiers des rêves incorporent des éléments du laboratoire, et ce, particulièrement dans les rêves en sommeil paradoxal lors d’une sieste matinale (article IV). Une étude qualitative de ces rêves met de l’avant les manières typiques par lesquelles des éléments du laboratoire réapparaissent dans les narratifs de rêve. Nous proposons l’existence de différentes « pressions intégratives » qui structurent les fragments de mémoire au sein de scénarios de rêves. Souvent, ces scénarios impliquent une certaine pression de performance, sont de nature sociale, projettent le rêveur dans le temps et dans l’espace, ou incorporent des sensations réelles du corps et de l’environnement de sommeil. Étudier le phénomène de « rêver au laboratoire » aide ainsi à clarifier comment les rêves sont façonnés autour de fragments de mémoire et souligne à la fois les avantages et les limites méthodologiques de l’étude des rêves et de la mémoire en laboratoire. Finalement, une troisième étude visait à suivre le décours temporel des sources de mémoire autobiographique des rêves au cours d’une nuit de sommeil entière en utilisant un protocole de réveils en série. Nos résultats montrent que les rêves peuvent combiner plusieurs sources de mémoire, en particulier lorsqu'ils se produisent en stade N1 ou en sommeil paradoxal, ce qui pourrait refléter une plus grande richesse ou capacité intégrative des rêves ayant lieu en ces stades (article V). Nous reproduisons le résultat voulant que les souvenirs récents sont préférentiellement réactivés tôt dans la nuit, tandis que les souvenirs plus lointains sont relativement plus représentés dans les rêves de fin de nuit – nous précisons que cet effet est indépendant des stades de sommeil. La co-activation de plusieurs sources de mémoire dans un même récit de rêve appuie la suggestion que l’une des fonctions du sommeil est d'intégrer les nouvelles connaissances à nos réseaux de mémoire préexistants. Nos résultats suggèrent que cette fonction pourrait être un processus cumulatif au cours d'une nuit de sommeil. Nous montrons entre autres qu'une seule source de mémoire peut être réactivée à plusieurs reprises dans plusieurs rêves, et en différents stades de sommeil, ce qui pourrait permettre un traitement continu ou séquentiel de souvenirs épisodiques avec d'autres souvenirs tout au long de la nuit. Dans l’ensemble, nos études quantitatives et qualitatives des incorporations de mémoire dans les rêves permettent d’éclairer les mécanismes fondamentaux de la formation des rêves ainsi que leurs associations avec le traitement et la consolidation des mémoires épisodique et procédurale. Nos résultats suggèrent qu’un rôle potentiel du rêve dans la mémoire irait au-delà de sa simple réactivation, soutenant des processus de transformation et d’intégration de la mémoire. La création de scénarios multisensoriels et immersifs basés sur des fragments mémoire est possiblement centrale à ces processus et permettrait d’optimiser l’utilisation de la mémoire pour le futur. / Sleep plays an important role in memory consolidation. New experiences acquired while awake are reactivated spontaneously during sleep, a process that is thought to facilitate their consolidation and integration into longer-term memory. It has been suggested that these memory reactivations are, at least partially, reflected in dream content and that dreams play an active role in memory consolidation. The general objective of this doctoral thesis is to assess these claims; I examine whether and how dreams are involved in episodic and procedural memory processes by using new technologies and experimental approaches to study relationships between memory and dreaming. Our first study aimed to influence memory reactivations during sleep in order to clarify their relationships with dreams and procedural learning. We experimentally stimulated memory reactivations by re-exposing participants during their sleep to an auditory stimulus previously associated with motor learning, a process called targeted memory reactivation (TMR). We show that TMR, when applied during rapid eye movement (REM) sleep, improves performance of a complex motor task, i.e., learning how to "fly" in a virtual reality (VR) setting. Moreover, dreaming about kinesthetic elements of the motor task in REM sleep, but not in stage 2 sleep, is associated with better improvement on this task (article I). These results support previous models suggesting that REM sleep plays an important role in the consolidation of complex procedural memory and further suggest that the simulation of sensorimotor sensations in dreams contribute to this role. Although TMR did not directly impact dreams, we show that it can influence the time course of memory incorporations in dreams over multiple days. It amplified delayed incorporations of the task 1-2 days later when applied in REM sleep, and 5-6 days later when applied in slow-wave sleep (article II). We suggest that these longer-term effects could be due to a “tagging” mechanism of memory traces, which primes or amplifies their subsequent processing over several nights of sleep. Furthermore, we show that our immersive VR task increased the incorporation of flying sensations in dreams, especially the night after exposure to it (article III). We identify individual factors that are associated with the incorporation of the flying task in dreams, such as previous experience with both flying and lucid dreams. A closer look at dreams over 10 days following the VR experience shows that flying sensations become progressively decontextualized from the original flying context over time. Flying dreams after VR exposure also had higher levels of control and emotional intensity compared to baseline flying dreams. The successful induction of flying dreams allowed us to do an in-depth qualitative analysis of them, based on which we propose a new mechanistic explanation of how flying sensations or movements may arise in dreams. These results could facilitate the development of technologies to better influence and study dreaming. Our second study aimed to assess when and how an episodic memory source shared by all participants – visiting the sleep laboratory – is incorporated into dreams. The results show that almost a third of dreams incorporate elements of the laboratory, particularly REM dreams from a morning nap (article IV). A qualitative study of these dreams highlights the typical ways in which elements of the laboratory reappear in dream narratives. We suggest the existence of different “integrative pressures” that structure memory fragments into these dream scenarios. These are often performative or social in nature, project the dreamer in time and space, or incorporate real sensations from the sleeping body or the sleep environment. Studying the phenomenon of dreaming about the laboratory helps clarify how dreams are shaped from memory fragments, and highlights the advantages and methodological limits of laboratory dream and memory studies. Finally, our third study evaluated the time course of autobiographical dream memory sources during an entire night of sleep using a serial awakenings protocol. Our results show that dreams can combine multiple memory sources at once, especially when they occur at sleep onset or in REM sleep, which may reflect a greater dream richness or a more widespread associative memory activation in those stages (article V). We replicate the finding that recent memories are preferentially reactivated early in the night, while more distant memories are relatively more represented in late night dreams – we here clarify that this effect is independent of sleep stages. The coactivation of multiple memory sources in a dream narrative aligns with the suggestion that a function of sleep is to integrate new knowledge with existing knowledge. Our results further suggest that the latter may be a cumulative function of a night of sleep. We show that a single memory source can be repeatedly reactivated in multiple dreams in different sleep stages, which could allow a continuous or sequential processing of episodic memories with other memories across the night. Overall, our quantitative and qualitative studies of memory incorporations in dreams shed light on fundamental mechanisms of dream formation and on their association with episodic and procedural memory processing and consolidation. Our results suggest that a potential role of dreams in memory goes beyond simple reactivation, supporting long-term processes of memory transformation and integration. The creation of immersive and multisensory dream scenarios built upon memory fragments may be key to these processes and to optimizing the use of these memories for the future.

研究背景:成人午睡對於認知與情緒影響的正面效益，已獲得許多研究證實，不過兒童夜間各睡眠期所占比例與成人不同，而且至今少有兒童午睡效益的研究，因此，本研究旨在探討短暫午睡對於國小學童認知功能、學習表現與情緒狀態的影響。 實驗設計與方法:以研究一實驗室情境，配合研究二教室現場實地研究兩種方式進行探討。研究一採組內設計，以30名國小五年級學童，在睡眠實驗室分別接受單日20分鐘的午睡與清醒的實驗，並以五種神經心理測驗，進行前測與後測，並以相依樣本t考驗進行比較兩種實驗情境在五種神經心理測驗表現的差異，並以性別×情境×時間三因子變異數分析，比較睏睡度與情緒的分數差異，並以皮爾森積差相關統計分析午睡睡眠參數資料與神經心理測驗分數的相關性。研究二採組內設計，以67名五年級學童，在兩週分別接受三日教室現場的午睡以及三日清醒情境的安排，並實施國語、數學、社會教學，作為午睡效益的評量依據，並以重複樣本t考驗比較兩種實驗情境國語科、數學科、社會科學習成效測驗分數是否有所差異，另以午睡習慣×實驗情境×時間三因子變異數分析，比較睏睡度與情緒量表分數的差異性。 研究結果:研究一發現受試者經歷20分鐘的午睡後，在專心度表現顯著比清醒好，不過午睡後的抑制刺激干擾的錯誤率卻顯著比清醒時高；至於在工作記憶、敘述性記憶、程序性動作記憶的表現，兩種情境則無顯著差異。另外，發現午睡後13:10的主觀睏睡度明顯比清醒時要低，在其他情緒狀態上則無顯著差異。而且發現睡眠第一期時間與抑制刺激干擾能力表現達顯著負相關；睡眠第二期時間與敘述性記憶表現成正相關:睡眠第三期時間則與敘述性記憶表現成負相關;:研究二則發現午睡後學生睏睡度顯著比沒午睡時要低，而且三日內15:30的睏睡度皆比剛睡醒13:10時要低，且第三日15:30睏睡度有顯著降低，但其他情緒則無顯著影響。另外，國語、數學、社會三科的學習成效，在兩種實驗情境皆無顯著差異。 結論:兒童午睡過程睡眠期與成人不太相同，且從兒童夜間睡眠與認知相關研究，也可以發現兒童似乎能夠補償短暫午睡缺乏，造成對認知功能損害或情緒的負面影響，因此，短暫午睡似乎對於兒童的正面顯著效益，並不如成人ㄧ般，不過，本研究實驗室或教室研究情境，皆ㄧ致發現兒童午睡仍能減少受試者主觀睏睡度，而且也發現隨著午睡日數增加所帶來的正面效益。未來，進行實地研究可以更嚴謹的睡眠偵測及判讀工具，來確認受試者午睡情況，減少主觀判斷與檢核所產生的誤差。 / Background: It has been confirmed by many researches that taking the afternoon nap has positive effects on adult cognition and emotion. However, the proportion of children’s sleep stages at night is quite different from that of adults. Since there are few studies on the effects of children’s afternoon nap, this paper aims to discuss the effects of short nap on cognitive ability, academic performance and emotional state of elementary school pupils. Experimental Design and Methods: The study mainly adopted two methods--------- laboratory situation and field study in the classroom. The first method was conducted among 30 fifth-grade pupils from the elementary school, with each one dealing with 20-minute long nap and sober status respectively in a day. Besides, five neuropsychological tests were carried out to pre-test and post-test their performance with the paired sample t-test to compare their difference. Based on the variance analysis of gender, situation as well as time factors, sleepiness degree and emotional difference were compared and the relationship between nap parameters and neuropsychological test scores was analyzed with Pearson's correlation analysis method. The second method was conducted among 67 fifth-grade pupils from the elementary school, dealing with afternoon nap and sober situation respectively for three days in two weeks. Besides, Chinese, Mathematics and Sociology were taught as the basis to assess the effects of afternoon nap with the paired samples t-test. Based on the variance analysis of nap habits, environmental situation and time factors, sleepy degree and emotional difference were compared. Research Result: The first study showed that concentration degree of pupils after 20-minute afternoon nap was much higher than that before sleeping, so was the error rate to inhibit stimulation’s interference. As for the performance in working, declarative and procedural motor memory, there was no significant difference. In addition, we found that the subject sleepiness degree after 13:10 was lower than that when awake and there was no significant difference in other emotional states. The duration of stageⅠwas significantly negative-related to the performance to inhibit stimulation’s interference, and the duration of stageⅡwas positive-related to declarative memory performance; while the duration of stageⅢwas negative-related to declarative memory performance. The second study showed that subjective sleepiness degree of pupils after afternoon nap was much lower than that before nappinging, so was the sleepiness degree of 15:30 much lower than that of 13:10 in three days. In particular, the sleepiness degree of 15:30 in the third day decreased significantly, while other emotional states were not affected greatly. What’s more, there was no significance between these two experimental situations on study effects of Chinese, Mathematics and Sociology Conclusion: Children have a different afternoon nap course from adults. Related researches on children’s night sleep and cognition show that children seem to be able to .compensate for the lack of a short nap, resulting in cognitive impairment or emotional impact of negative.Therefore, the positive benefit of short nap of children is not as significant as that of adults. However, both laboratory and classroom situation showed that children’s afternoon nap could still reduce the subjective sleepiness. As the napping days increased, the positive effect was much more evident. In the near future, more rigorous sleep state detection and scoring tools for field study can be used to identify the nap situation and to reduce subjective misunderstanding and detection errors.

The desire to enhance and make ourselves better is not a new one and it has continued to intrigue throughout the ages. Individuals have continued to seek ways to improve and enhance their well-being for example through nutrition, physical exercise, education and so on. Crucial to this improvement of their well-being is improving their ability to remember. Hence, people interested in improving their well-being, are often interested in memory as well. The rationale being that memory is crucial to our well-being. The desire to improve one’s memory then is almost certainly as old as the desire to improve one’s well-being. Traditionally, people have used different means in an attempt to enhance their memories: for example in learning through storytelling, studying, and apprenticeship. In remembering through practices like mnemonics, repetition, singing, and drumming. In retaining, storing and consolidating memories through nutrition and stimulants like coffee to help keep awake; and by external aids like notepads and computers. In forgetting through rituals and rites. Recent scientific advances in biotechnology, nanotechnology, molecular biology, neuroscience, and information technologies, present a wide variety of technologies to enhance many different aspects of human functioning. Thus, some commentators have identified human enhancement as central and one of the most fascinating subject in bioethics in the last two decades. Within, this period, most of the commentators have addressed the Ethical, Social, Legal and Policy (ESLP) issues in human enhancements as a whole as opposed to specific enhancements. However, this is problematic and recently various commentators have found this to be deficient and called for a contextualized case-by-case analysis to human enhancements for example genetic enhancement, moral enhancement, and in my case memory enhancement (ME). The rationale being that the reasons for accepting/rejecting a particular enhancement vary depending on the enhancement itself. Given this enormous variation, moral and legal generalizations about all enhancement processes and technologies are unwise and they should instead be evaluated individually. Taking this as a point of departure, this research will focus specifically on making a case for ME and in doing so assessing the ESLP implications arising from ME. My analysis will draw on the already existing literature for and against enhancement, especially in part two of this thesis; but it will be novel in providing a much more in-depth analysis of ME. From this perspective, I will contribute to the ME debate through two reviews that address the question how we enhance the memory, and through four original papers discussed in part three of this thesis, where I examine and evaluate critically specific ESLP issues that arise with the use of ME. In the conclusion, I will amalgamate all my contribution to the ME debate and suggest the future direction for the ME debate.