I samband med åldrandet ses ofta en försämring av människors kognitiva förmågor, däribland det episodiska minnet, vilket är avgörande för vardagligt fungerande och livskvalitén för äldre. Livsstilsfaktorer som fysisk aktivitet (FA) och övervikt har tidigare kopplats till hälsosamt åldrande och visat sig påverka graden av försämring. Hur FA och övervikt interagerar på lång sikt för att påverka det episodiska minnet för äldre behöver dock fortfarande utredas. Denna studie undersökte både de enskilda effekterna av FA och övervikt på det episodiska minnet, samt hur dessa faktorer interagerar på lång sikt. Därtill undersöktes skillnader mellan sjuka och friska äldre deltagare. Data från deltagare (n = 5 287) i the English Longitudinal Study on Aging i åldrarna 50 och äldre användes i ett longitudinellt upplägg. Självskattade mått på FA och viktstatus från en tidpunkt användes för att predicera poäng på ett minnestest vid en tidpunkt fyra år senare, med och utan kontrollvariabler. Statistiskt signifikanta effekter av FA på minne kunde ses både med och utan kontrollvariabler, men tydliga effekter av övervikt kunde inte ses. Interaktioner mellan övervikt och FA kunde endast upptäckas i modeller utan kontrollvariabler, och inte alls i modeller med enbart sjuka deltagare. Slutsatser om överviktens påverkan på det episodiska minnet kunde inte dras, men resultatet ger vidare stöd till att FA hjälper till att bevara minnet i åldrandet. Sammantaget förklarades dock mer av variansen i episodiskt minne av kontrollvariabler som ålder och utbildningsnivå. / With aging often comes declining cognitive function, with episodic memory being one of the declining factors crucial for everyday functioning and quality of life among the elderly. Lifestyle factors such as physical activity (PA) and overweight have been associated with healthy aging and the trajectory of the decline. How PA and overweight interact in affecting episodic memory over time among the elderly is, however, still in need of further investigation. The present thesis investigated both the direct effects of PA and overweight on episodic memory, and how the interaction between these factors affect episodic memory. Furthermore, differences in the effects between participants with or without illnesses were examined. Data from participants (n = 5 287) in the English Longitudinal Study on Aging aged 50 and older were used in a longitudinal design. Self-reported measures of PA as well as measures of weight- status from time point 1 was used to predict scores on a memory test at a second time point, four years later, with and without control variables. Statistically significant effects of PA on memory score were detected, both with and without control variables. No statistically significant effects of overweight were detected. Interactions between overweight and PA could only be detected in models without control variables, and not at all among participants with illnesses. Conclusions on the effect of overweight on episodic memory could not be reached, but further support is lent to PA’s role in preserving memory function in aging. In closing more of the variance in episodic memory was attributed to other factors such as increasing age and higher education levels.

Episodic memory (EM) displays the most prominent age-related decline. However, this decline could possibly be minimized by engaging in a physically active and cognitively stimulating lifestyle. A way to measure the self-perceived ability to engage in such a lifestyle is with subjective health estimations, which have been associated with objective health. The Subjective Health Horizon Questionnaire (SHH-Q) measures estimated individual maximum age to engage in activities in relation to four lifestyle dimensions: Novelty, Body, Work and Life Goals. Among these, Novelty is suggested to be associated with EM performance. Thus, in this study, the first aim is to corroborate that the SHH-Q items align according to the hypothesized dimensions. The second aim is to assess whether any of the dimensions are associated with EM. In this cross-sectional study 129 Swedish participants, aged 69-73, were evaluated with the SHH-Q and three EM tests. Statistical analyses included Principal Component Analysis (PCA) for aim 1 along with a correlation- and linear regression analysis for aim 2. The results showed that the SHH-Q items aligned with the four dimensions as expected, but that the linear regression model with the SHH-Q in relation to EM was not significant. However, a significant positive zero-order correlation between Novelty and EM (r(90) = .19, p = .04) was found. The association between Novelty and EM highlights the possibility that engaging in novelty-oriented exploration, such as new experiences and environments, may be associated with preserved EM performance at older ages. Future research should investigate the neural correlates of this association. / Episodminnet har visat en stark åldersrelaterad försämring. Denna nedgång skulle möjligen kunna minimeras med en fysiskt aktiv och kognitivt stimulerande livsstil. Ett sätt att mäta den självupplevda förmågan att engagera sig i en sådan livsstil är med subjektiva hälsomått, som även har associerats med objektiv hälsa. Subjective Health Horizon Questionnaire (SHH-Q) mäter uppskattad individuell maxålder för engagemang i aktiviteter i relation till fyra dimensioner av livsstil: Novelty, Body, Work och Life Goals. Bland dessa föreslås Novelty vara associerad med episodminnesprestation. Det första målet med denna studie är att korroborera att frågorna i SHH-Q kan delas in i de tidigare föreslagna dimensionerna. Det andra målet är att bedöma om någon av dimensionerna är förknippade med episodminnet. I denna tvärsnittsstudie utvärderades 129 svenska deltagare i åldern 69-73, med SHH-Q och tre EM-tester. Statistiska analyser inkluderar principiell komponentanalys för mål 1 tillsammans med en korrelations- och linjär regressionsanalys för mål 2. Resultatet visade att SHH-Q frågorna kan delas in i de fyra dimensionerna som förväntat, men den linjära regressionsmodellen med SHH-Q i relation till episodminne var inte signifikant. Däremot fanns en signifikant positiv korrelation mellan Novelty och episodminne (r(90) = .19, p = .04). Associationen mellan Novelty och episodminne betonar möjligheten att engagemang i novelty-orienterat utforskande, såsom nya erfarenheter och miljöer, kan vara associerat med bevarad episodminnesprestation vid högre ålder. Framtida forskning bör utforska de neurala korrelaten av denna association.

Episodic memory forms a fundamental aspect of human memory that accounts for the storage of events as well as the spatio-temporal relations between events during a lifetime. These spatio-temporal relations in which episodes are embedded can be understood as their contexts. Contexts play a crucial role in episodic memory retrieval. Despite this, little work has been done in the computational neuroscience literature on trying to investigate this relationship further. These interactions can be modelled with attractor neural networks such as the Bayesian Confidence Propagation Neural Network (BCPNN). In this project, the interaction between contextual aspects and memory items are studied by developing an abstract computational model of episodic memory retrieval. The effect of increasing the number of items associated with a particular context on the overall recall performance is examined. Finally, the role of synaptic plasticity modulation of certain item-context associations on recall is also analysed. It is found that an inverse relationship exists between the number of items associated with a context and their subsequent recall rates, i.e. as the number of items associated with an episodic context increase, the recall rates of the corresponding items decrease. Furthermore, it is found that the item-context pairs for which the synaptic plasticity is modulated during learning, have a significantly higher recall rate than the remaining unmodulated associations. / Episodiskt minne utgör en grundläggande aspekt av det mänskliga minnet som står för lagring av händelser samt de spatio-temporala relationerna mellan dem under en livstid. De spatio-temporala relationer i vilka episoderna är inbäddade kan betraktas som deras kontexter, vilka spelar en avgörande roll i episodisk minnesåterkallande. Trots detta har inte mycket forskning inom beräkningsneurovetenskapi gjorts för att närmare undersöka bakomliggande neurala mekanismer. Minnesåterkallandet inklusive interaktioner mellan kontext och minnesobjekt kan modelleras med återkopplade neurala nätverk, s k attraktornät, t ex av typen för Bayesian Confidence Propagation Neural Network (BCPNN). I det här projektet studeras interaktionen mellan kontextuella aspekter och minnesobjekt genom att utveckla en abstrakt BCPNN-modell av episodisk återkallande. Effekten av att variera antalet objekt-kontextassociationer på återkallningsbeteende undersöks. Slutligen analyseras också effekten av synaptisk plasticitetsmodulering av vissa minnesobjekt-kontext-associationer på korrekt minnesåterkallelse. Det observeras att när antalet objekt associerade med ett sammanhang ökar, minskar återkallningsfrekvensen för motsvarande objekt. Vidare är det konstaterat att minnesobjektföremålet-kontextpar för vilka den synaptiska plasticiteten moduleras under lärande, har en betydligt högre återkallningsgrad än de återstående omodulerade föreningarna.

Les plaques amyloïdes, composées d’agrégats de protéines bêta-amyloïde, sont l’un des principaux marqueurs physiopathologiques de la maladie d’Alzheimer et peuvent s’accumuler jusqu’à trois décennies avant les premiers signes cliniques. Il n’est pas encore bien établi dans quelle mesure le vieillissement cognitif normal pourrait dépendre de la présence de cette pathologie cérébrale. Par ailleurs, la réserve cognitive reflète le décalage parfois observé entre le niveau de pathologie et les manifestations cliniques de démence. En plus d’être associée à un risque réduit de développer une maladie neurodégénérative, la réserve cognitive rend compte d’une susceptibilité réduite de présenter un déclin cognitif associé au vieillissement normal. Cependant, la littérature demeure mitigée quant à l’effet protecteur de la réserve cognitive face à une charge amyloïde élevée à un stade où la cognition est cliniquement normale. L’objectif général de cette thèse était donc d’acquérir une meilleure compréhension de la relation entre la charge amyloïde, la cognition et la réserve cognitive au sein du vieillissement normal. Cette question de recherche a été étudiée grâce à la participation d’un groupe de 104 personnes âgées (77 femmes, âge moyen de 73 ans). Suivant une procédure de dépistage permettant de recruter uniquement des aînés sans trouble cognitif, une batterie d’épreuves neuropsychologiques a été administrée à partir de laquelle une mesure de mémoire épisodique a été extraite. Puis, l’imagerie par résonance magnétique et la tomographie par émission de positons ont permis d’établir la charge amyloïde de chaque participant. La première étude avait comme objectif de documenter chez cette population, d’une part, l’impact de la charge amyloïde sur l’efficience de la mémoire épisodique, et d’autre part, l’effet de la scolarité sur cette relation. Les résultats de cette étude ont permis d’appuyer l’idée que la performance en mémoire épisodique est associée à la charge amyloïde, relation qui est modérée par la scolarité. Plus précisément, cette association demeure significative jusqu’à 13.5 années d'études, alors qu’au-delà de ce seuil, la pathologie n’a plus d’impact sur les performances en mémoire. Ce résultat est cohérent avec celui démontrant que les performances en mémoire épisodique des participants ayant un diplôme d’études secondaires et collégiales étaient significativement affectées par les dépôts amyloïdes comparativement au groupe d’universitaires. La deuxième étude visait à évaluer l’effet protecteur d’autres proxys de réserve cognitive reconnus comme pouvant compenser les effets de l’âge et d’une pathologie cérébrale, soit la profession, le vocabulaire et les activités cognitivement stimulantes liées au style de vie. L’effet de différents indexes composites de réserve ont aussi été examinés. Lorsque considérés individuellement, seule la profession modère significativement la relation entre la charge amyloïde et la mémoire épisodique. Enfin, la combinaison de la profession et de la scolarité démontre la plus grande taille d'effet relativement à la modération de l’impact du fardeau amyloïde sur la mémoire épisodique. Cette thèse met en évidence l’impact de la charge amyloïde sur l’efficience de la mémoire épisodique dans le vieillissement normal. Néanmoins, les personnes âgées cognitivement normales ayant une réserve cognitive mieux développée seraient protégées contre l’effet délétère qu’entraîne cette pathologie sur la mémoire épisodique. / Amyloid plaques, aggregates of beta-amyloid proteins, are one of the main pathophysiologic markers of Alzheimer's disease and can accumulate up to three decades before the first clinical signs. It is unclear to what extent normal cognitive aging might depend on the presence of this brain pathology. Furthermore, cognitive reserve reflects the discrepancy that can be observed between the level of pathology and the clinical manifestations of dementia. In addition to being associated with a reduced risk of developing a neurodegenerative disease, cognitive reserve accounts for the reduced susceptibility to cognitive decline associated with aging. However, whether cognitive reserve may help withstand the effect of high amyloid load among cognitively normal older adults is still unclear. The general objective of this thesis was therefore to gain a better understanding of the relationship between amyloid load, cognition and cognitive reserve in normal aging. This research question was investigated through a sample of 104 older adults (77 women, mean age 73 years). Following a screening procedure which allowed to recruit only older adults with clinically normal cognition, a battery of neuropsychological tests was administered from which a measure of episodic memory was extracted. Participants underwent magnetic resonance imaging and positron emission tomography in order to quantify beta-amyloid load in each participant. The first study aimed to better characterize in this population, on the one hand, the impact of amyloid deposition on the efficiency of episodic memory, and on the other hand, the effect of education against this pathology. Performance in episodic memory was significantly associated with amyloid load, and this relationship was moderated by education. More precisely, the association remained significant up to 13.5 years of education, whereas beyond this threshold, amyloid load no longer had an impact on episodic memory performances. This result is consistent with the fact that the episodic memory performance of participants with a high school and college diploma were significantly affected by amyloid deposits compared to participants with a university degree. The second study aimed to investigate the protective effect of cognitive reserve against amyloid burden by means of other well-documented proxies of cognitive reserve that help better cope with age or pathology, such as occupation, vocabulary and cognitively stimulating lifestyle activities. The effect of different composite indexes of cognitive reserve was also examined. Taken individually, only occupation significantly moderated the relationship between amyloid load and episodic memory. In addition, when combined with education, this composite index of cognitive reserve demonstrated the largest effect size relatively to the moderation of the impact of amyloid burden on episodic memory. This thesis highlights the impact of amyloid load on episodic memory efficiency in normal aging. Furthermore, cognitively normal older adults with higher cognitive reserve appear to be protected against the deleterious effect of amyloid load on episodic memory.

[pt] Através da memória episódica o indivíduo tem a capacidade de recordar experiencias anteriormente armazenadas, além de utiliza-la em processos como a aprendizagem e ao elaborar metas futuras. Entretanto é uma função que sofre declínio no envelhecimento, repercutindo negativamente na vida social e psicológica do idoso. As diversas estratégias de intervenção cognitiva surgem como propostas que visam reduzir as perdas da memória. A presente dissertação tem como intuito abordar aspectos teóricos e empíricos da intervenção cognitiva e seu efeito na memória episódica. O primeiro capitulo consiste em uma revisão sistemática, na qual buscou-se identificar os principais modelos de treino cognitivo da memória episódica em idosos saudáveis e clínicos. Foi realizado uma busca em quatro bases de dados: PubMed; PsycNET, Web of Science e Scielo através do método PRISMA, restando 23 artigos finais. Os dados coletados dos trabalhos analisados sugerem eficácia dentre as diferentes abordagens de treino cognitivo, porém, apesar de ser um tema bastante estudado, carece de mais estudos empíricos acerca de outras formas de treino cognitivo. O segundo capitulo ilustra um estudo empírico que mensurou o efeito da intervenção cognitiva em idosos saudáveis participantes do programa de estimulação cognitiva Neuro Academia da memória. Quinze idosos saudáveis participaram da pesquisa e como instrumentos para avaliação da memória episódica foram utilizados o RAVLT e o Ruche. Como resultado, encontrou-se diferença dentre grupos experimental e controle em momentos pré e pós intervenção cognitiva baseando-se na curva de aprendizagem. Entretanto, a mensuração da memória episódica através do treinamento cognitivo necessita de novas produções. / [en] Through episodic memory, the individual has the ability to recall previously stored experiences, in addition to using it in processes such as learning and in developing future goals. However, it is a function that suffers a decline in aging, with a negative impact on the social and psychological life of the elderly. The different cognitive intervention strategies appear as proposals that aim to reduce memory losses. This dissertation aims to address theoretical and empirical aspects of cognitive intervention and its effect on episodic memory. The first chapter consists of a systematic review, in which we sought to identify the main models of cognitive training of episodic memory in healthy and clinical elderly. A search was performed in four databases: PubMed; PsycNET, Web of Science and Scielo through the PRISMA method, leaving 23 final articles. The data collected from the analyzed studies suggest efficacy among the different approaches to cognitive training, however, despite being a widely studied topic, it lacks further empirical studies about other forms of cognitive training. The second chapter illustrates an empirical study that measured the effect of cognitive intervention in healthy elderly people participating in the Neuro Academy of Memory cognitive stimulation program. Fifteen healthy elderly people participated in the research and RAVLT and Ruche were used as instruments to assess episodic memory. As a result, a difference was found between experimental and control groups in moments before and after cognitive intervention based on the learning curve. However, measuring episodic memory through cognitive training requires new productions.

La présente thèse examine les liens entre le sommeil, la mémoire épisodique et les rêves. Dans une première étude, nous utilisons les technologies de la réalité virtuelle (RV) en liaison avec un paradigme de privation de sommeil paradoxal et de collecte de rêve en vue d'examiner l'hypothèse que le sommeil paradoxal et le rêve sont impliqués dans la consolidation de la mémoire épisodique. Le sommeil paradoxal a été associé au rappel des aspects spatiaux des éléments émotionnels de la tâche RV. De la même façon, l'incorporation de la tâche RV dans les rêves a été associée au rappel des aspects spatiaux de la tâche. De plus, le rappel des aspects factuels et perceptuels de la mémoire épisodique, formé lors de la tâche VR, a été associé au sommeil aux ondes lentes. Une deuxième étude examine l'hypothèse selon laquelle une fonction possible du rêve pourrait être de créer de nouvelles associations entre les éléments de divers souvenirs épisodiques. Un participant a été réveillé 43 fois lors de l'endormissement pour fournir des rapports détaillés de rêves. Les résultats suggèrent qu'un seul rêve peut comporter, dans un même contexte spatiotemporel, divers éléments appartenant aux multiples souvenirs épisodiques. Une troisième étude aborde la question de la cognition lors du sommeil paradoxal, notamment comment les aspects bizarres des rêves, qui sont formés grâce aux nouvelles combinaisons d'éléments de la mémoire épisodique, sont perçus par le rêveur. Les résultats démontrent une dissociation dans les capacités cognitives en sommeil paradoxal caractérisée par un déficit sélectif dans l'appréciation des éléments bizarres des rêves. Les résultats des quatre études suggèrent que le sommeil aux ondes lentes et le sommeil paradoxal sont différemment impliqués dans le traitement de la mémoire épisodique. Le sommeil aux ondes lentes pourrait être implique dans la consolidation de la mémoire épisodique, et le sommeil paradoxal, par l'entremise du rêve, pourrais avoir le rôle d'introduire de la flexibilité dans ce système mnémonique. / The present dissertation examines relationships between sleep, episodic memory and dreaming. In Articles I and II we use a novel virtual reality (VR) task in conjunction with a rapid eye movement (REM) sleep deprivation (REMD) paradigm and dream sampling to examine the hypothesis that REM sleep and dreaming are involved in the consolidation of episodic memory. REM sleep was associated with the successful recall of the spatial aspects of emotionally charged elements of the VR task. Similarly, dreaming was associated with improved performance on the spatial aspects of the recall task. Recall of the factual and perceptual aspects of episodic memories formed with the VR task was associated with increased slow wave sleep (SWS) during the post-exposure night. Overall, the results suggest that SWS is associated with the perceptual and factual aspects of episodic memories while REM sleep is not, a finding which may relate to observations that REM sleep dreaming is composed of deconstructed fragments of loosely associated episodic memories. Study II examines the hypothesis that a function of dreaming may be to create new associations between previously unrelated memory items. A participant, highly trained in introspection and mentation reporting, was awakened 43 times during theta bursts at sleep onset and provided detailed reports of resulting imagery and associated memory sources. This technique provided evidence that elements of distally related memory sources are brought together in temporal and spatial proximity within a novel context provided by the dream, suggesting a role for dreaming in memory processing. To allow for this possibility, we speculate that dreaming experiences may be functionally equivalent to waking experiences in their ability to induce neural plasticity. Study III addresses an aspect of this functional equivalence by examining if dream bizarreness is incompatible with behavioral and cognitive features associated with waking state experience-driven plasticity, i.e., whether the dreamer can act upon, emote and be motivated towards an element of the dream that is bizarre and that violates basic assumptions of physical reality. The results demonstrate a dissociation in cognitive ability during dreaming characterized by a selective deficiency in appreciating bizarreness in face of a maintained ability for logical thought. This finding thus addresses the problem of the wake-like mind reflecting upon dream bizarreness and suggests that dreaming is a state in which the cognitive aspects associated with synaptic plasticity (attention, emotion and motivation associated with believing a situation to be reality) are present while allowing for the presentation of memory item combinations which may transcend the limits of physical reality. The results of the four studies are discussed in light of how REM and SWS sleep stages are differentially involved in specific aspects of episodic memory (episodic replay vs. episodic novelty) and the possible role that dreaming, as a driver of synaptic plasticity, may have in these relationships.

[pt] A Epilepsia do Lobo Temporal (ELT) é a forma mais comum de epilepsia em adultos, com uma proporção considerável de pacientes que não respondem a diferentes abordagens terapêuticas e precisam recorrer à intervenção cirúrgica. A ELT está ligada a déficits cognitivos, mas poucos estudos investigaram habilidades metacognitivas nesse grupo. Dois estudos foram conduzidos para avaliar a metacognição e a metamemória em pacientes adultos com lesões temporais direitas ou esquerdas associadas à ELT refratária após neurocirurgia. No Estudo 1, foram utilizadas tarefas experimentais computadorizadas de Manipulação de Sucesso-Fracasso de memória e de tempo de reação e metacognição sendo medida pela discrepância entre estimativas pós- teste e desempenho real. O Estudo 2 explorou metamemória para testes de memória episódica verbal e visual com estimativas globais de desempenho antes e depois dos ensaios. Os resultados do Estudo 1 indicam que os pacientes podem discriminar as condições de sucesso e fracasso, particularmente para tarefas de tempo de reação. O estudo 2 indicou que os pacientes com lesão no hemisfério esquerdo apresentam um padrão de superestimação, tanto para a memória visual quanto verbal, em relação aos pacientes do hemisfério direito. Esses resultados são discutidos em relação à potencial ajuda da metacognição em intervenções terapêuticas, especialmente na criação de estratégias compensatórias que possam ajudar a melhorar a qualidade de vida na ELT. / [en] Temporal Lobe Epilepsy (TLE) is the most common form of epilepsy in adults, with a considerable proportion of patients who do not respond to different therapeutic approaches and have to resort to surgical intervention. TLE is linked to cognitive deficits, but few studies have investigated metacognitive abilities in this group. Two studies were conducted to assess metacognition and metamemory on adult patients with right or left temporal lesions associated with refractory TLE after neurosurgery. In Study 1, computerized experimental Success-Failure Manipulation tasks exploring memory and reaction time were used, with participants doing easy (success) and hard (failure) tasks for each task type and metacognition being measured by discrepancy between post-test estimations and actual performance. Study 2 explored metamemory for verbal and visual episodic memory tests with global estimations of performance before and after trials. Results of Study 1 indicate that patients can discriminate the success and failure conditions, particularly for reaction time tasks. Study 2 indicated that left hemisphere patients show a pattern of overestimation, both for visual and verbal memory, in relation to right hemisphere patients. These results are discussed in relation to the potential aid of metacognition in therapeutic interventions, especially in the creation of compensatory strategies that can help improving quality of life in TLE.

Under de senaste åren har intresset för test baserat lärande ökat och det förekommer evidensatt detta fenomen fungerar inom flera områden som bland annat test format, personligaegenskaper samt återkoppling från ett test. En aspekt som det däremot finns få studier av ärtestbaserat lärande i relation till individuella skillnader i kognition. Den föreliggande studienfokuserar därför på individuella skillnader avseende arbetsminneskapacitet och episodisktminne och dess effekter på ihågkomst av svenska-swahili-ordpar. I studien ingick 163gymnasieelever, varav 82 var flickor och 81 var pojkar med en medelålder om 17.10 år.Multipla regressionsanalyser undersökte deltagarnas förmåga att minnas 60 svenska-swahiliordparfyra veckor efter inlärningsperioden. Analysen visade att både arbetsminneskapacitetoch episodiskt minne predicerar långtidsretention för studerade ordpar. För testbaserat lärandevar det endast det episodiska minnet som signifikant predicerade retentionen. Studien indikeraratt det episodiska minnet, är centralt både för att studera ordpar och att lära in ordpar genomtestbaserat lärande. Däremot är det enbart arbetsminnet som har betydelse för att lära sig ordparvia att studera ordparen. / During the last years, the interest for test-enhanced learning have increased and robust evidenceconcerning test format, personal characteristics and feedback have been obtained. However,few studies have examined test-enhanced learning in relation to cognition. The present studytherefore focused on examine the individual differences in working memory capacity and theepisodic memory and the effects of those on recall of Swedish- Swahili word pairs. The studyincluded 163 students whereof 82 girls were and 81 were boys, with a mean age of 17.10 years.Multiple regressions investigated whether the participated could correctly recall 60 Swedish-Swahili word pairs four weeks after the learning session. The analysis showed that both theepisodic memory and working memory capacity predicted long-term retention for studied wordpairs. For test based learning only the episodic memory had a significant prediction for longterm retention. The study indicate that the episodic memory is central both for learning throughstudy and learning through test-enhanced learning. While working memory was important onlylearning through study.

Quick work out sessions has been shown to improve students’ academic performance. Furthermore, certain cognitive functions have also been shown to improve academic performance. The aim of this study was therefore to investigate if quick work out sessions can improve certain cognitive functions and whether these functions could act as mediator variables between exercise and academic performance. Thirty participants were randomly assigned to a control group that was shown a music video (n=15) and an experiment group that was asked to use a step up exercise device (n=15). Cognitive shifting, episodic memory and perceptual speed were tested in both groups, before and after the intervention. The result didn’t show a significant effect on any cognitive function. This might be explained by the low amount of participants, considering that similar studies often have small effects.Key words: acute exercise, cognitive shifting, episodic memory, perceptual speed. / Korta träningspass har visat sig förbättra elevers skolprestation. Vidare har också vissa kognitiva förmågor visat sig förbättra skolprestation. Denna studies syfte var därför att se om korta träningspass kan förbättra vissa kognitiva förmågor och huruvida dessa förmågor då skulle fungera som mediatorvariablermellan träning och skolprestation. Trettio deltagare delades slumpmässigt in i en kontrollgrupp som fick se en musikvideo (n=15) och en experimentgrupp som fick gå upp och ner för en step up-bräda (n=15). Kognitiv skiftning, episodiskt minne och mentalt tempo testades i båda grupper, före och efter interventionen. Resultatet visade inte på någon signifikant effekt på någon kognitiv förmåga. Detta kan bero på det låga antalet deltagare, då effekter av liknande studier ofta är små.

Le fardeau vasculaire (présence de maladies vasculaires et/ou cérébrovasculaires) est associé à une augmentation des troubles cognitifs chez les personnes âgées, ainsi qu’à un plus haut risque de démence vasculaire (DV) et de démence de type Alzheimer (DTA). Un nombre restreint de travaux a porté sur l’impact du fardeau vasculaire sur la cognition des personnes avec trouble cognitif léger (TCL). Pourtant, les personnes avec TCL représentent une population d’intérêt puisqu’elles sont à haut risque d’évoluer vers une démence. Cette thèse comprend trois articles de revue qui visent à exposer les connaissances entourant la santé vasculaire et la cognition des personnes âgées et trois articles empiriques (Chapitres 5, 6, 7). La première étude empirique traite de l’impact du fardeau vasculaire sur la cognition des personnes TCL et a comme objectif de spécifier quelles fonctions cognitives sont affectées par le fardeau vasculaire et dans quelle mesure le fardeau vasculaire influence l’hétérogénéité des TCL (Chapitre 5). Dans le cadre de la deuxième étude, nous avons examiné l’intégrité des processus stratégiques et non stratégiques de mémorisation des TCL avec et sans fardeau vasculaire, afin d’évaluer si ces processus diffèrent quantitativement et qualitativement entre ces deux groupes (Chapitre 6). Enfin, dans la troisième étude nous avons évalué les capacités d’association (binding) ainsi que la résistance à l’interférence des personnes TCL, les liens entre ces processus mnésiques et différents marqueurs cérébraux en plus des facteurs permettant de prédire l’évolution vers une démence (Chapitre 7). Les résultats présentés dans cette thèse appuient l’hypothèse selon laquelle le fardeau vasculaire influence le profil cognitif des TCL. Dans un premier temps, nous avons montré que le fardeau vasculaire est associé à une atteinte exécutive plus importante chez les TCL (Chapitre 5). De plus, nos résultats suggèrent que le fardeau vasculaire influence la classification clinique de ces derniers, puisque ceux dont le fardeau est élevé répondent davantage aux critères de TCL amnestique domaine multiple (trouble de mémoire plus au moins un autre déficit cognitif) tandis que ceux sans fardeau répondent davantage aux critères de TCL amnestique domaine unique (trouble isolé de la mémoire). Dans un deuxième temps, nous avons montré des différences dans la nature des processus mnésiques atteints chez les TCL avec et sans fardeau vasculaire (Chapitre 6). Alors que les premiers présentent une atteinte prédominante des processus stratégiques de mémorisation, les seconds présentent une atteinte des processus stratégiques et non stratégiques de mémorisation. Lorsque seuls les résultats des TCL ayant évolué vers une démence sont analysés, le patron d’atteinte est similaire puisque les TCL vasculaires sont quantitativement moins touchés que les TCL non-vasculaires au niveau des processus non-stratégiques de mémorisation. Enfin, tant les TCL qui progressent vers une démence que les TCL qui restent stables après un suivi de trois ans éprouvent tous des difficultés de mémoire associative et sont sensibles à l’interférence proactive (Chapitre 7). De plus, le fardeau vasculaire est associé à la sensibilité à l’interférence alors que le volume hippocampique est associé aux difficultés de mémoire associative. Enfin, nos résultats indiquent que les TCL qui éprouvent des difficultés de mémoire associative sont plus à risque d’évoluer vers une démence que les TCL ne présentant pas ces mêmes difficultés. De façon globale, les résultats de cette thèse révèlent que le fardeau vasculaire joue un rôle important dans l’hétérogénéité des TCL. / Vascular burden (presence of vascular diseases and/or cerebrovascular diseases) increase cognitive deficits in older adults and have been associated with vascular dementia and Alzheimer’s diseases. However, only a few studies have examined the impact of vascular burden on cognitive functioning in persons with mild cognitive impairment (herein referred to as MCIs). Individuals with MCI are a target population for research since they are at high risk of developing dementia. Understanding the factors that influence MCIs cognition is thus a priority. This thesis aims to identify the impact of vascular burden on MCI’s cognition. First, a summary of the literature concerning vascular health and cognitive functioning in the elderly is presented here (Chapters 1, 2, 3 and 4). Then, three studies that represent the core of this thesis are exposed. The first one aims to identify which cognitive functions are affected by vascular burden in MCIs (Chapter 5). In the second one, we assess strategic and non strategic memory processes in MCI with and without vascular burden (Chapter 6). Finally, in the last study, we assess binding and sensitivity to proactive interference in MCIs who progress to dementia, and MCIs who remain stable in a three-year follow-up (Chapter 7). This latter study also assesses which brain changes influence binding and interference capacity in MCIs and which factors predict progression to dementia. Results of this thesis first revealed that vascular burden plays an important role in cognitive heterogeneity of MCIs. First, MCIs who present a high vascular burden have more executive deficits. Second, those same MCIs run a greater risk of being clinically classified as amnestic multiple domain MCIs (memory impairment plus impairment in at least one cognitive domain, whereas MCIs with no vascular burden run a greater risk of being classified as amnestic single domain MCIs (isolated memory impairment) (Chapter 7). In the second article of this thesis, we showed that MCIs with vascular burden have memory impairment restricted to strategic memory processes. When only the results of MCIs who progressed to dementia were analysed, a similar pattern of memory impairment was found, since MCIs with vascular burden were less impaired in non strategic than strategic processes, whereas both processes were impaired in MCIs with no vascular burden (Chapter 8). Finally, MCIs who progressed to dementia, and those who remained stable after a three-year follow-up, showed binding difficulties and vulnerability to proactive interference. This difference was particularly evident when only MCI progressors were compared to healthy controls. In summary, vascular burden plays a role in the cognitive heterogeneity of MCI.