The central theme of the present thesis revolves around the exploration of similarities and differences in brain activity patterns invoked by the component processes underlying mnemonic, executive and attentional functions. The primary aim was to identify and functionally characterize commonly recruited brain regions in terms of shared component processes, which has been a largely neglected area of research in cognitive neuroscience. The vast majority of functional brain imaging investigations of cognition has focused on delineating differences between cognitive functions or processes, with the purpose of isolating the unique functional neuroanatomy that underlies specific cognitive domains. By contrast, the present thesis builds on the results from three imaging studies that focused primarily on detecting commonalities in functional brain activity across different forms of memory processes. In study I, the imaging data from two positron emission tomography (PET) experiments were re-analyzed to identify common activation patterns associated with nine different memory tasks incorporated across the experiments, three each separately indexing working memory, episodic memory, and semantic memory. A generic prefrontal cortex (PFC) network involving discrete subregions of the left hemisphere located in ventrolateral (BA 45/47), dorsolateral (BA 9/44/46), and frontopolar (BA 10) sectors of PFC, as well as a midline portion of the frontal lobes, encompassing the dorsal part of the anterior cingulate cortex (ACC) (BA 24/32), was conjointly recruited across all tasks. In study II, we used a novel mixed blocked/event-related functional magnetic resonance imaging (fMRI) design, which enables separation of brain responses associated with different temporal dynamics to further investigate commonalities of neural activation across working memory, episodic memory, semantic memory, and attention/vigilance. A similar set of common PFC regions, as that discovered in Study I, was found to elicit overlapping brain activity across all memory tasks, with a subset of regions also activated in the attention/vigilance task. Furthermore, the task-induced brain activity was dissociated in terms of the temporal profiles of the evoked neural responses. A common pattern of sustained activity seen across all memory tasks and the attention task involved bilateral (predominantly right-lateralized) ventrolateral PFC (BA 45/47), and the dorsal ACC (BA 24/32), which was assumed to reflect general processes of attention/vigilance. A pattern of sustained activity elicited in all memory tasks, in the absence of attention-related activity, involved the right frontopolar cortex (BA 10), which was assumed to reflect control processes underlying task set maintenance. In addition, common transient activation evoked in the memory tasks relative to the attention task was found in the dorsolateral (BA 9/44) and ventrolateral (BA 47) PFC, the superior parietal cortex (BA 7), and cerebellum. In study III, a mixed fMRI design was used to assess the degree of common brain activity associated with increased executive demand, which was independently manipulated within episodic and working memory. Unitary control modulations involved a shared tonic executive component subserved by fronto-striatal-cerebellar circuitry, assumed to govern top-down context processing throughout task periods, and a stimulus-synchronous phasic component mediated by the intraparietal sulcus (BA 7), assumed to support dynamic shifting of the ‘focus of attention’ among internal representations. Collectively, the theoretical implications of shared neural mechanisms are discussed, with a special focus on human memory and its multifaceted relationships with attention and executive control functions. Finally, the presented imaging data are used to outline a tentative hierarchical neurocognitive model that attempts to give an account of how different unitary component processes might work together during cognitive task performance.

The aim of this study was to investigate the development of release from proactive interference (RPI) and its relations with executive working memory functions. 101 primary school children (aged 6-12 years) and 20 young adults (aged 22-30 years) participated in the study. The main task, the Categorical Free Recall Test, comprised 12 items from 3 different categories (animals, fruits, clothes). The purpose of the main task was to examine both the development of the RPI pattern and the categorization ability during childhood. As our results showed, the categorization ability and the RPI pattern were already present in the 1st graders. Although overall memory span increased with age, there was no significant development for the categorization and the RPI effect. For the additional tasks, the Word Span Test (WST, to measure the phonological WM capacity), the Wisconsin Card Sorting Test (WCST, to measure both the categorization ability and executive WM functions), and the Listening Span Test (LST, to examine executive and complex WM functions), the results indicated that children also improved with age. Overall memory capacity in the main task was best predicted by the WST / however, memory of serial position was best predicted by the LST. These findings are in accordance with the view that the WST measures the phonological working memory span, whereas the LST measures complex working memory and executive functions. The comparisons between the adult and the child sample revealed that except for the RPI pattern adults were better on all tasks than the children. The lack of a consistent RPI pattern for the adults may be due to the relatively short stimulus list.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Barns fem första levnadsår präglas av en omfattande utveckling av språkliga förmågor och exekutiva funktioner, vilka är färdigheter som visat sig ha en stor påverkan på hur barn utvecklar förståelse för sina egna och andras tankar, det vill säga deras Theory of Mind. En central aspekt inom forskning har varit att undersöka hur förmågorna samvarierar vid olika åldrar. Syftet i föreliggande studie var att undersöka sambandet mellan Theory of Mind, språkliga förmågor och exekutiva funktioner hos barn i tre års ålder med typisk utveckling. Av intresse var även att undersöka om det förelåg skillnader i resultat mellan pojkar och flickor samt om de del-tagande barnens demografiska förhållanden vad gäller antal äldre och/eller yngre syskon, socio-ekonomisk status och vuxenkontakt påverkade de deltagande barnens Theory of Mind. Totalt medverkade 30 barn med typisk utveckling, varav 16 var flickor och 14 var pojkar. Åldersanpassade testmaterial användes för att undersöka Theory of Mind, grammatisk förmåga, semantisk förmåga, kognitiv flexibilitet, arbetsminne och fonemdiskrimination. Den demografiska informationen inhämtades i form av en enkät som föräldrarna fick fylla i. Resultatet indikerar att treåriga barns förmåga att hantera och förstå Theory of Mind-uppgifter samvarierar med både grammatisk förmåga och kognitiv flexibilitet. Samvariationer påträffades även mellan grammatisk förmåga och kognitiv flexibilitet, vilket stärker att språk, exe-kutiva funktioner och ToM har ett beroendeförhållande till varandra. Föreliggande studie framhåller att samtliga förmågor är mer eller mindre integrerade vid olika åldrar och korrelationerna visar på att vissa delförmågor inom språk, ToM och exekutiva funktioner går hand i hand och utvecklas i samspel med varandra. Specifikt kan den exekutiva komponenten kognitiv flexibilitet och den språkliga förmågan grammatik ses som viktiga förmågor för just treåriga barns ToM. / A childs’ first five years are characterized by an extensive development of language abilities and executive functions. These are skills that have demonstrated large impact on how children develop their understanding of their own and others’ thoughts, that is, their Theory of Mind. Within contemporary research, a central question has been to investigate how these abilities correlate at different stages of age.  The aim of the present study was to examine the relationship between Theory of Mind, language and executive functions in typically developed three-year-old children. A central part in this study was also to assess whether differences in performance between boys and girls occurred and also if the number of younger and/or older siblings, socioeconomic status, and adult contact did affect the children’s performance.  A total of 30 children with typical development participated, of whom 16 were girls and 14 were boys. Age-appropriate test materials were used to examine, Theory of Mind, grammatical ability, semantic ability, cognitive flexibility, working memory, and phonetic discrimination. The demographic information was based on a questionnaire that parents of the participating children had to answer.  The result of this study indicates that the three-year child's ability to manage and understand tasks that assess Theory of mind seems to covariate with both grammatical skills and cognitive flexibility. A Correlation was also found between grammatical skills and cognitive flexibility, which indicate that language ability, executive functions and ToM have a strong dependent relationship.  The present study confirms that all abilities are more or less integrated at different ages and the correlations indicate that certain abilities in language, ToM and executive functions are de-veloped in interaction with each other. Specifically, the executive component cognitive flexibility and the grammatical ability are important abilities for three-year children’s ToM.

A pervasive real-world memory task is remembering to carry out intended activities at appropriate moments in the future, such as remembering to call one’s mother after returning from work or to hand a message to a colleague when seeing him in the office on the next morning. Such types of tasks are termed prospective memory (PM) tasks (Einstein & McDaniel, 1996). PM has been identified as one of the most frequent everyday memory challenges (e.g., Maylor, 1990), particularly in old age (McDaniel, Einstein, & Rendell, 2008) and an intact PM is considered to be crucial for the maintenance of independent living (Kliegel & Martin, 2003). Therefore, many researchers have focused on the exploration of possible age differences in PM. While age-related deficits were found in standard lab-based PM tasks, age-related benefits occured in naturalistic tasks that are carried out in participants’ everyday lives. This surprising pattern has been called the age-PM-paradox (Rendell & Craik, 2000). It has been supported by a meta-analysis comparing PM age effects found in studies that focused either on lab-based or on naturalistic PM tasks (Henry, MacLeod, Phillips, & Crawford, 2004). However, the mechanisms which are critical in determining the direction of age effects remain poorly delineated. Thus, the overall aim of the research programme presented in the present thesis was to investigate the age-PM-paradox as well as potential cognitive, motivational and emotional mechanisms and processes associated with age-related PM performance. For that purpose, three experimental studies were conducted testing adult age effects in different PM task settings with different task material. Furthermore, several possible underlying mechanisms suggested by the literature on age effects in PM were measured and/ or varied experimentally. The first aim of Study 1 was to cross-validate the age-PM-paradox within a single sample. The second aim was to empirically explore the relative importance of four recently proposed factors (motivation, metacognitive awareness, activity absorption, and control over the task) that may be associated with the direction of age effects inside and outside of the laboratory. For that purpose, 20 young and 20 older adults performed a lab-based and a naturalistic PM task, which were similar in structure and demand. The level of control was experimentally manipulated in both task settings. The remaining possibly influencing factors (motivation, metacognitive awareness, and activity absorption) were assessed via questionnaires in the laboratory and with a daily diary in the field. First, analysing mean level age differences, the paradox was confirmed. Second, exploring possible correlates of the paradox revealed that the level of daily activity absorption (i.e., everyday stress) was the most important mechanism in naturalistic PM performance. Further, high motivation and good metacognitive awareness were associated with age benefits in PM performance in the naturalistic task, while high ongoing activity absorption and low control over the PM cue were related to deficits in lab-based tasks. Thus, Study 1 confirmed the age-PM-paradox within one sample and with carefully matched lab-based and naturalistic tasks. In addition, the results indicate that the relative importance of the suggested factors may vary as a function of setting. While cognitive factors were most influential in the laboratory, motivational and knowledge-based factors were associated with high PM performance in the naturalistic task. The strong association between PM performance in the field and everyday stress highlights the need for future studies exploring the mechanisms underlying this effect. Results from Study 1 suggest that cognitive resources are most influential for PM age effects in the laboratory. Yet, it is not clear, which specific cognitive resources are needed for successful PM performance and if these processes differ between young and older adults. Thus, Study 2 explored the role of executive functions (i.e. shifting, updating and inhibition) as possible developmental mechanisms associated with PM age effects. 170 young and 110 older adults performed a battery of cognitive tests including measures of PM, shifting, updating, inhibition, working memory and speed. A comprehensive set of statistical approaches (e.g. median analyses, structural equation modelling) was used to analyze the possible cognitive correlates in predicting PM performance. First, age effects were confirmed in PM and also obtained in measures of executive control. Moreover, the facets of executive control differently predicted PM performance. Specifically, shifting was the strongest predictor of PM performance in young and older adults as well as for explaining age differences in PM. Thus, Study 2 clarified the role of different facets of controlled attention in age effects in PM and bears important conceptual implications: The results suggest that executive functions are important developmental mechanisms of PM across adulthood beyond working memory and speed. Specifically, shifting appeared to be an essential aspect of cognitive control involved in age-related PM performance. Moreover, examining PM as a latent construct confirmed the convergent and discriminant validity of PM. This demonstrates PM as a separate cognitive construct and suggests that PM is related to, but not identical with, executive control. Study 3 was set out to explore if the amount of cognitive resources needed to successfully perform a PM task in the laboratory can be influenced by the emotionality of the task material. First studies suggested that emotional task material may enhance PM performance in young and older adults by heightening the salience of the task and thereby reducing the need for controlled attention. However, the extent and mechanisms of this effect are still under debate. Therefore, Study 3 explored possible differential effects of PM target cue valence on PM age effects. For that purpose, 45 young and 41 older adults performed a PM task in which emotional valence of the PM cue was manipulated (positive, negative, neutral). Results revealed an interaction indicating that age differences were smaller in both emotional valence conditions compared to the neutral condition. This finding supports an emotionally enhanced memory effect in PM, but only for the older adults as PM performance in young adults was not affected by cue valence. From a conceptual perspective, the results from Study 3 may also contribute to the explanation of the age-PM-paradox, as they suggest that the neutral material usually applied in lab-based studies might overestimate PM age effects. In summary, the present thesis makes an important contribution to the ongoing conceptual debate concerning adult age effects in PM performance assessed in the laboratory versus participants’ everyday lives. Results strongly suggest that mostly different variables may be crucial for understanding PM age deficits in the laboratory and age benefits in naturalistic PM tasks. Successful PM performance in the laboratory seems to require high levels of cognitive resources. The present results suggest that shifting ability is especially relevant in this respect. On a task level the emotionality of the material seems to influence the required amount of cognitive resources as it reduced PM age effects. Everyday stress seems to be particularly important for successful PM performance in the field. Thus, possible future studies should specify the relation between stress and PM as outlined in the general discussion.

There is limited knowledge of cognitive outcome extending beyond 5 years after childhood traumatic brain injury, CTBI. The main objectives of this thesis were to investigate cognitive outcome at 6-14 years after CTBI, and to evaluate if advancements in the neurosurgical care, starting 1992, did influence long-term outcome and early epidemiology. An additional aim was to study the relationship between early brain injury parameters and early functional outcome. Study 1 evaluated cognitive progress during 14 years after CTBI, over three neuropsychological assessments in 8 patients with serious CTBI. Study 2 used patient records to investigate early epidemiology, received rehabilitation and medical follow up in two clinical cohorts, n=82 and n=46, treated neurosurgically for CTBI before and after 1992. An exploratory cluster analysis was applied to analyse the relation between early brain injury severity parameters and early functional outcome. In Study 3, participants in the two cohorts, n=18 and n=23, treated neurosurgically for CTBI before and after 1992, were subject to an extensive neuropsychological assessment, 13 and 6 years after injury, respectively. Assessment results of the two cohorts were compared with each other and with controls. Data were analysed with multivariate analyses of variance. Results and discussion. There were significant long-term cognitive deficits of similar magnitude and character in the two cohorts with CTBI, treated before and after the advancements in neurosurgical care. At 6-14 years after injury, long-term deficits in verbal intellectual and executive functions were found, and were discussed in terms of their late maturation and a decreased executive control over verbal memory-functions after CTBI. Visuospatial functions had a slightly better long-term recovery. The amount of rehabilitation received was equally low in both cohorts. The length of time spent in intensive care and the duration of care in the respirator may have a stronger relationship to early outcome than does a single measure of level of consciousness at admission. Main conclusions are that cognitive deficits are apparent at long-term follow up, 6-13 years after neurosurgically treated CTBI, even after advancements in the neurosurgical care in Sweden. Measures of verbal IQ, verbal memory and executive functions were especially low while visuospatial intellectual functions appear to have a better long-term recovery. / At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.

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Submitted by Ronildo Prado (ronisp@ufscar.br) on 2017-08-21T17:55:55Z No. of bitstreams: 1 DissSDO.pdf: 583517 bytes, checksum: b554029a0300ceef3bc4fe8b2681fca5 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-21T17:56:03Z (GMT) No. of bitstreams: 1 DissSDO.pdf: 583517 bytes, checksum: b554029a0300ceef3bc4fe8b2681fca5 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-21T17:56:10Z (GMT) No. of bitstreams: 1 DissSDO.pdf: 583517 bytes, checksum: b554029a0300ceef3bc4fe8b2681fca5 (MD5) / Made available in DSpace on 2017-08-21T17:56:17Z (GMT). No. of bitstreams: 1 DissSDO.pdf: 583517 bytes, checksum: b554029a0300ceef3bc4fe8b2681fca5 (MD5) Previous issue date: 2017-03-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neuropsychology is a science that allows one to draw the profile of cognitive impairment and skills preserved in order to design possible treatments and appropriate educational practices, aiming for better quality of life of the individual. Among the cognitive abilities investigated by neuropsychology, executive functions refers to a system that manages the cognitivebehavioral resources, with the purpose of behavior planning and regulation. This study is a correlational basic research aimed to verify whether the results found in neuropsychological evaluations of executive functions in children with Autism Spectrum Disorder (ASD) are predictive of or show any correlation with the performance of these children in conditional discrimination via identity matching-to-sample (MTS) tasks. A battery of neuropsychological tests were used to evaluate executive function to identify participants’ existing and missing skills, with possible quantification and qualification of the results. The tests used were Wisconsin, Test Tracks Pre-School, Corsi blocks and Attention Test for Cancellation. A portable microcomputer and the Master computer program were used to present MTS tasks. The participants were 13 children with ASD, aged 4 to 12 years, regularly enrolled in a Special Institution / Regular Education School. The correlations revealed significant associations between neuropsychological tests and MTS tasks performance. In general, it was observed that the lower the performance in Test Wisconsin, more perseverative responses were presented and higher correlation was found with the MTS tasks. It was also observed that the better the performance in the Cancellation and trails tests, better performance on MTS tasks. The attention and cognitive flexibility may be pre-requisites for better performances in MTS tasks. Future research could further explore the MTS tasks for evaluation of cognitive and attentional flexibility and intervention of individuals with ASD. Another possibility is to check whether training with several exemplars of identity MTS would improve performance on neuropsychological tests. / A neuropsicologia trata-se de uma ciência que permite traçar o perfil dos comprometimentos cognitivos e das habilidades preservadas afim de possível delineamento de tratamentos e práticas educativas adequadas, almejando melhor qualidade de vida do indivíduo. Assim essa é uma pesquisa básica correlacional, cujo objetivo foi verificar se os resultados encontrados em avaliações neuropsicológicas das funções executivas em crianças com Transtorno do Espectro do Autismo (TEA) são preditivas de ou tem alguma correlação com o desempenho dessas crianças em discriminação condicional por meio de tarefas de escolha de acordo com o modelo (MTS) de identidade. Para isso foi utilizado uma bateria de testes neuropsicológicos para avaliação das funções executivas para identificar habilidades preservadas e comprometidas dos participantes, com possível quantificação e qualificação dos resultados. Os testes utilizados foram: Wisconsin, Teste de Trilhas para Pré-Escolares, Blocos de Corsi e Teste de Atenção por Cancelamento. Foram utilizados também um microcomputador portátil e o programa computacional Mestre para apresentar as tarefas de MTS. Os participantes da pesquisa foram 13 crianças com Transtorno do Espectro do Autismo, com idade entre 4 e 12 anos, regularmente matriculadas em uma Instituição Especial/ Escola Regular de Ensino. As correlações revelaram associações significativas entre os testes neuropsicológicos e as tarefas de MTS. De maneira geral, foi possível observar que quanto menor o desempenho no Teste Wisconsin, mais respostas perseverativas foram apresentadas e maior a correlação com as tarefas de MTS e que quanto melhor foi o desempenho nos testes de Cancelamento e de Trilhas, melhor o desempenho nas tarefas de MTS. Esses resultados sugerem que a atenção e a flexibilidade cognitiva são quesitos para o melhor cumprimento das tarefas de MTS. Pesquisas futuras poderão explorar melhor as tarefas de MTS para avaliação de flexibilidade cognitiva e atencional e intervenção de indivíduos com TEA. Outra possibilidade é verificar se treinos com vários exemplares de relações de identidade em tarefas de MTS melhorariam o desempenho nos testes neuropsicológicos.