Le vieillissement, normal ou pathologique, s’accompagne de déficits marqués de la mémoire épisodique et de la mémoire de travail. Dès lors, est-il possible d’optimiser l’apprentissage moteur en s’appuyant sur d’autres registres de mémoire éventuellement moins affectés, voire épargnés, par les effets du temps ? Dans les trois expériences que nous avons menées, la prédominance d’un registre de mémoire sur un autre a été manipulée en contrastant les effets, lors de la réalisation de 160 essais d’une tâche sensorimotrice (le putting au golf), de deux méthodes distinctes d’apprentissage : la méthode en condition d’erreurs fréquentes supposée solliciter les processus mnésiques déclaratifs (mémoire épisodique et mémoire de travail) vs la méthode en condition d’erreurs peu fréquentes supposée solliciter les processus mnésiques procéduraux. Dans l’Étude 1, nous avons testé, chez des adultes jeunes et âgés, l’efficacité de ces méthodes et la nature des processus en jeu lors de la réalisation simultanée d’une tâche secondaire coûteuse en attention. Dans l’Étude 2, nous avons comparé les performances motrices entre des adultes jeunes, plus âgés, et des patients Alzheimer. Dans l’Étude 3, nous avons évalué les effets de la verbalisation des actions motrices produites durant l’apprentissage sur les processus mnésiques sous-tendant la performance motrice d’adultes jeunes et plus âgés. Les résultats de l’Étude 1 montrent que l’apprentissage est affecté par le vieillissement lorsque prédominent les processus déclaratifs mais qu’il est préservé des effets du temps lorsque prédominent les processus procéduraux. Les résultats de l’Étude 2 démontrent que l’apprentissage est préservé des effets de la maladie d’Alzheimer lorsque prédominent les processus procéduraux. Les résultats de l’Étude 3 révèlent que la verbalisation affecte les processus déclaratifs mais n’a pas d’effet sur les processus procéduraux chez les adultes jeunes et qu’elle n’a aucun effet sur ces deux types de processus chez les adultes plus âgés. Ces résultats attestent qu’il est possible de « contourner » la mémoire déclarative et les déficits survenant avec l’âge ou avec la maladie en s’appuyant sur une mémoire procédurale intacte, ce qui a pour effet d’optimiser l’apprentissage moteur. / Normal or pathological aging is characterized by specific deficits in episodic and working memories. Therefore, is it possible to optimize motor learning with advancing age, by utilizing other memory processes hypothesized to be less affected or even spared from aging? We conducted three experiments in which the predominance of one memory system over another was manipulated by contrasting the effects, across 160 trials of a sensorimotor task (golf putting), of two different learning methods: the infrequent-error method hypothesized to primarily rely upon declarative memory vs. the frequent–error method hypothesized to primarily rely upon procedural memory. In Experiment 1, we tested in young and older adults the efficiency of these methods and the nature of processes involved when a secondary, attention-demanding task was performed concurrently. In Experiment 2, we compared the motor performance between young and older adults and Alzheimer patients. In Experiment 3, we assessed the effects of verbalizing previous motor actions produced during learning on processes underlying young and older adults’ motor performance. The results of Experiment 1 showed that learning is affected by aging when declarative processes are predominant but is protected from advancing age when procedural processes are predominant. The results of Experiment 2 demonstrated that learning is preserved from Alzheimer’s disease when procedural processes are predominant. The results of Experiment 3 revealed that verbalization affects declarative processes but has no effect on procedural processes in young adults, and that it has no effect on these two types of processes in older adults. Altogether, these results show that “bypassing” declarative memory and its deficits occurring with advancing age or disease is doable by utilizing intact procedural memory, thus leading to an optimized motor learning.

Declarative memory is characterized as a conscious, explicit memory. Declarative memory consists of two essential systems, semantic memory and episodic memory. Episodic memory enables us to recall specific past events. A simplified model, so called Episodic-like memory is often used to study episodic memory mechanisms. According to this model, all events are stored in a contextual framework consisting of three basic components: identity of the object ('what' happened), temporal information ('when' it occurred) and spatial information ('where' did it happen). This type of memory is testable not only in humans but also in animal models. Aim of this diploma thesis is to study the neuronal substrate of individual components of episodic memory in healthy volunteers by means of functional magnetic resonance imaging (fMRI) and ecologically valid tasks designed in virtual reality environment. Results obtained in the fMRI paradigm show that apart from common neuronal substrate of episodic memory, additional brain structures are responsible for recollection of individual components of the episodic-like memory. Behavioral data indicate that the demands of the recollection of individual components is not equivalent. Additional analyses with parcellation of the brain to individual structures and consecutive...

Cognitive deficit presents a significant problem affecting the life of schizophrenia patients. Despite the variability of the deficit, which influences almost all cognitive domains, the most profound seems to be deficit in memory and executive functioning with direct impact on daily functioning of patients with schizophrenia. As the pharmacologic interventions do not seem to bring satisfying results, the cognitive remediation seems to bet the most effective way of intervention of the deficit. Efficacy of cognitive remediation approach was repeatedly confirmed on the level of structural and functional changes of the brain. Nevertheless, often discussed are the issues of ecological validity of cognitive remediation and its controversial ability of transfer of acquired abilities and skills into the real life. In this work, we present development of a new method potentially applicable in the remediation of deficit of declarative memory in schizophrenia patients designed in ecologically valid environment of virtual supermarket. In the first two pilot studies, we tested the functionality of the task in the healthy volunteers and we compared their performance in the virtual task with the results in standard psychological memory tests. After considering the findings from the pilot studies, we verified the...

Developmental dyslexia is a specific reading and spelling disability with several explanatory proposals. Previous research has shown that there is a strong relation between developmental dyslexia and difficulties in phonological processing, which has resulted in the theory that the cause of developmental dyslexia is a specific weakness in phonological awareness. However, such a specific weakness does not explain the non-linguistic difficulties that are also common in developmental dyslexia. According to the Procedural Deficit Hypothesis (PDH), several (both linguistic and non-linguistic) difficulties that are observed in developmental dyslexia can be explained by abnormal development of the procedural memory system. Moreover, this hypothesis implies that the declarative memory system remains intact and may have a compensatory role for the reading disabilities in developmental dyslexia. In this study, the aspect of declarative memory that is visual recognition memory after incidental encoding was examined. 10 children with diagnosed developmental dyslexia and 10 typically developed children participated in the study. The results indicated an intact declarative memory in children with developmental dyslexia. However, no significant correlation between declarative memory and reading ability was found. Thus, the prediction that declarative memory can serve a compensatory role in developmental dyslexia was not supported. / Dyslexi är en specifik läs- och skrivsvårighet med flera förklaringsmodeller. Tidigare forskning har visat på ett starkt samband mellan dyslexi och svårigheter med fonologiskt processande, vilket har lett fram till hypotesen att orsaken till dyslexi är en specifik svaghet i fonologisk medvetenhet. En sådan specifik nedsättning kan dock inte förklara de icke-språkliga svårigheter som också är vanligt förekommande vid dyslexi. Enligt the procedural deficit hypothesis (PDH) kan många (både språkliga och icke-språkliga) svårigheter vid dyslexi förklaras av en nedsättning i det procedurella minnet. Vidare innebär hypotesen att det deklarativa minnet är intakt och kan fungera som kompensation för svårigheterna vid dyslexi. I denna studie undersöktes det deklarativa minnet i form av visuellt igenkänningsminne efter oavsiktlig inkodning. I studien deltog 10 barn med dyslexi och 10 barn utan dyslexi. Resultatet indikerade att det deklarativa minnet var intakt hos barnen med dyslexi. Däremot kunde inget signifikant samband mellan deklarativt minne och läsförmåga ses. Antagandet att deklarativt minne kan fungera som kompensation vid dyslexi kunde därför inte stödjas.

Die transkranielle Gleichstromstimulation (tDCS) erwies sich in der bisherigen Grundlagenforschung als bewährte Methode zur Aufschlüsselung von komplexen kognitiven Funktionen. Bisher deuten bildgebende Verfahren auf ein Zusammenwirken parietaler und temporaler Kortizes beim Rekognitionsprozess deklarativer Gedächtnisinhalte hin. In der vorliegenden Arbeit sollten nun die Auswirkungen einer bilateral temporal und parietal applizierten tDCS auf die deklarative Gedächtnisleistung während der Rekognition untersucht werden. Unter Verwendung eines einfach-blinden, kontrollierten und randomisierten Studiendesigns wurden junge, gesunde Probanden drei voneinander unabhängigen, hinsichtlich der individuellen Gedächtniskapazität ausgeglichenen Studiengruppen für Placebo-, parietale und temporale Stimulation zugeordnet. Während der Bearbeitung eines computergestützten Alt-Neu-Rekognitions-Paradigmas erhielten zwei Gruppen bilaterale tDCS mit linkshemisphärischer a-tDCS über dem parietalen bzw. temporalen Kortex und eine Gruppe Placebo-Stimulation. Zielsetzend wurde die Einflussnahme der tDCS auf die deklarative Rekognitionsleistung bezüglich verbaler Gedächtnisinformationen gemessen. Eine Verbesserung der deklarativen Rekognitionsleistung äußerte sich in höheren Trennschärfeindex- und Treffgenauigkeitswerten der beiden verumstimulierten Gruppen im Vergleich zur Placebo-stimulierten Gruppe. Ein konträres Dissoziationsmuster zeigte sich insofern, als die temporale Stimulationsgruppe eine signifikant höhere Treffgenauigkeit bei der Rekognition alter Items im Vergleich zu neuen aufwies und die parietale Stimulationsgruppe mit einer signifikant höheren Treffgenauigkeit neue Items im Vergleich zu alten wiedererkannte. Diese Ergebnisse unterstreichen die Involvierung der temporalen und parietalen Hirnareale in möglicherweise unterschiedliche Stadien des Rekognitionsprozesses deklarativer Gedächtnisinhalte.

Cognitive functioning is important for managing work and life in general. However, subjective cognitive complaints (SCC), involving self-perceived difficulties with concentration, memory, decision making, and clear thinking are common in the general and in the working population and can be coupled with both lowered well-being and work ability. The present thesis investigated the extent to which SCC among people in the work force can be explained by objective cognitive functioning (study I &amp; II) and working conditions (study III), utilizing samples from the working population. The potential roles of other common psychological problems which often co-occur with SCC were also investigated in studies I-III. In Study I, high levels of SCC were associated with significantly poorer episodic memory performance during high executive demands and a trend was found towards poorer episodic memory, while not being associated with semantic memory. In Study II, high levels of SCC were associated with significantly poorer executive cognitive performance on all three executive cognitive tests used. Symptoms of depression, chronic stress and sleeping problems were found to play an important role in the relations between SCC and episodic memory during divided attention in study I and executive cognitive functioning in study II. In Study III, in all cross-sectional data analyses, high quantitative demands, information and communication technology (ICT) demands, underqualification in the work situation and inter-personal conflicts were positively associated with SCC, whereas social support, good resources at work and overqualification in the work situation were negatively associated with SCC. In all prospective data analyses, quantitative job demands, ICT demands and underqualification were positively associated with future SCC, including when adjusted for baseline cognitive complaints. The findings may guide prevention of and interventions for SCC among people in the work force. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Submitted. Paper 2: Accepted.</p>

Utifrån the procedural deficit hypothesis (PDH) antas det deklarativa minnet vara intakt hos personer med dyslexi. Detta styrks av studier som visat att deklarativt minne är intakt eller förstärkt hos barn med SLI eller dyslexi då det undersökts med icke-språkliga minnestest. Personer med dyslexi som genomgår universitetsstudier antas kompensera för sina svårigheter på olika sätt, bland annat med det deklarativa minnet. I denna studie har deklarativt minne undersökts i form av visuellt igenkänningsminne efter oavsiktlig inkodning. Deltagarna utgjordes av 11 universitetsstuderande med dyslexi samt en kontrollgrupp på 26 universitetsstuderande utan dyslexi. Resultatet indikerade ett intakt deklarativt minne hos personer med dyslexi. En trend till att de även har ett förstärkt minne efter 24 timmar jämfört med kontrollgruppen kunde skönjas men var inte signifikant. Prediktionen att deklarativt minne används som kompensation i allmänhet samt för nedsatt läsförmåga kunde inte styrkas. Andra möjliga kompensatoriska strategier och förmågor än deklarativt minne diskuteras. / Based on the procedural deficit hypothesis (PDH) declarative memory is assumed to be intact in people with dyslexia. This is supported by studies showing that declarative memory is intact or enhanced in children with SLI or dyslexia when examined using non-verbal memory tests. People with dyslexia who undergo university studies are assumed to compensate for their difficulties in different ways, including with the use of declarative memory. This study examines the aspect of declarative memory that is visual recognition memory after incidental encoding. The participants were 11 university students with dyslexia and a control group of 26 university students without dyslexia. The results showed an intact declarative memory in people with dyslexia. A possible trend that they also have an enhanced memory after 24 hours compared with the control group could be seen but was not significant. The prediction that declarative memory is used as compensation in general and for impaired reading skills could not be substantiated. Other possible compensatory strategies and abilities besides declarative memory are discussed.

Recent research, that has been focused on recognition memory, has revealed that two processes contribute to recognition of previously encountered items: recollection and familiarity (Aggleton & Brown, 1999; Eichenbaum, 2006; Eichenbaum, Yonelinas, & Ranganath, 2007; Rugg & Yonelinas, 2003; Skinner & Fernandes, 2007; Squire, Stark, & Clark, 2004; Wixted, 2007a; Yonelinas, 2001a; Yonelinas, 2002). The findings of neural correlates of recollection and familiarity lead to the assumption that there are different brain regions activated in either process, but there are, to the best of my knowledge, no studies assessing how these brain regions are working together in a recollection or a familiarity network, respectively. Additionally, there are almost no studies to date, which directly searched for overlapping regions. Therefore, in study I of the current thesis, brain regions associated to both recognition processes are searched investigated. Additionally, a connectivity analysis will search for functional correlated brain activations that either build a recollection or a familiarity network. It is undoubtable that the Brain Derived Neurotrophic Factor (BDNF) is strongly involved in synaptic plasticity in the hippocampus (Bramham & Messaoudi, 2005) and there is evidence that a genetic variant of this neurotrophin (BDNF 66Met) is related to poorer memory performance (Egan, et al., 2003). Therefore, in study II of the current thesis, the effect of BDNF Val66Met on recollection and familiarity performance and related brain activations is investigated. Finally, one could summarize, that serotonin, like BDNF, is strongly involved in brain development and plasticity as well as in learning and memory processes (Vizi, 2008). More precisely, there is evidence for alterations in the structure of brain regions, which are known to be involved in emotional memory formation and retrieval, like amygdala and hippocampus (Frodl, et al., 2008; Munafo, Brown, & Hariri, 2008; Pezawas, et al., 2005). One study found an slight epistatic effect of BDNF and 5-HTTLPR on the grey matter volume of the amygdala (Pezawas, et al., 2008). Therefore, in study III, it is investigated if such an interaction effect could be substantiated for the amygdala and additionally revealed for the hippocampus. The results of the current thesis allow further comprehension of recollection, hence episodic memory, and point to a special role of the BDNF in temporal and prefrontal brain regions. Additionally, the finding of an epistatic effect between BDNF and serotonin transporter function point to the need of analyzing interactions between genes and also between genes and environmental factors which reveals more information than the study of main effects alone. In conclusion, analyzing behavioral and neural correlates of episodic memory reveal allowed insights in brain functions that may serve as guideline for future studies in clinical populations with memory deficits, including susceptibility factors such as good or bad environment, as well as promising gene variants that influence episodic memory.

Slow-wave sleep plays an important role in consolidation of declarative memory. From electrophysiological point of view, this process is dependent on a common occurrence and mutual integration of neocortical slow oscillations (< 1 Hz), hippocampal sharp-wave ripples (150-250 Hz) and thalamo-cortical sleep spindles (10-15 Hz). Previous studies demonstrated that periodic acoustic stimulation by pink noise pulses applied at frequency of sleep slow oscillation during slow wave sleep leads to prolongation of slow wave sleep and to enhancement in declarative memory performance in normal sleepers. Our study investigated this kind of periodic acoustic stimulation in its relation to sleep architecture and declarative memory of people suffering from insomnia due to which there often comes to a reduction in slow wave sleep which positively correlates with worsening of declarative memory performance. Our aim was to investigate if this kind of comparatively non-invasive brain stimulation has a potential to increase a total length of slow wave sleep and enhance declarative memory performance in insomnia. Our study revealed acoustic stimulation neither improved declarative memory performance nor it increased total length of slow-wave sleep. No positive association was found between level of declarative memory...

Recent research, that has been focused on recognition memory, has revealed that two processes contribute to recognition of previously encountered items: recollection and familiarity (Aggleton & Brown, 1999; Eichenbaum, 2006; Eichenbaum, Yonelinas, & Ranganath, 2007; Rugg & Yonelinas, 2003; Skinner & Fernandes, 2007; Squire, Stark, & Clark, 2004; Wixted, 2007a; Yonelinas, 2001a; Yonelinas, 2002). The findings of neural correlates of recollection and familiarity lead to the assumption that there are different brain regions activated in either process, but there are, to the best of my knowledge, no studies assessing how these brain regions are working together in a recollection or a familiarity network, respectively. Additionally, there are almost no studies to date, which directly searched for overlapping regions. Therefore, in study I of the current thesis, brain regions associated to both recognition processes are searched investigated. Additionally, a connectivity analysis will search for functional correlated brain activations that either build a recollection or a familiarity network. It is undoubtable that the Brain Derived Neurotrophic Factor (BDNF) is strongly involved in synaptic plasticity in the hippocampus (Bramham & Messaoudi, 2005) and there is evidence that a genetic variant of this neurotrophin (BDNF 66Met) is related to poorer memory performance (Egan, et al., 2003). Therefore, in study II of the current thesis, the effect of BDNF Val66Met on recollection and familiarity performance and related brain activations is investigated. Finally, one could summarize, that serotonin, like BDNF, is strongly involved in brain development and plasticity as well as in learning and memory processes (Vizi, 2008). More precisely, there is evidence for alterations in the structure of brain regions, which are known to be involved in emotional memory formation and retrieval, like amygdala and hippocampus (Frodl, et al., 2008; Munafo, Brown, & Hariri, 2008; Pezawas, et al., 2005). One study found an slight epistatic effect of BDNF and 5-HTTLPR on the grey matter volume of the amygdala (Pezawas, et al., 2008). Therefore, in study III, it is investigated if such an interaction effect could be substantiated for the amygdala and additionally revealed for the hippocampus. The results of the current thesis allow further comprehension of recollection, hence episodic memory, and point to a special role of the BDNF in temporal and prefrontal brain regions. Additionally, the finding of an epistatic effect between BDNF and serotonin transporter function point to the need of analyzing interactions between genes and also between genes and environmental factors which reveals more information than the study of main effects alone. In conclusion, analyzing behavioral and neural correlates of episodic memory reveal allowed insights in brain functions that may serve as guideline for future studies in clinical populations with memory deficits, including susceptibility factors such as good or bad environment, as well as promising gene variants that influence episodic memory.