Le vieillissement normal est associé à une réorganisation cérébrale qui peut être influencée par plusieurs facteurs. Des théories comme la réserve cognitive de Stern (2002) tentent d’expliquer les effets de ces différents facteurs. Certains, le niveau de scolarité par exemple, sont encore mal connus. Pourtant, le niveau de scolarité est connu pour avoir un impact sur les performances cognitives tout au long de la vie. Le but de ce mémoire est d’étudier les effets du niveau de scolarité sur l’oxygénation cérébrale de personnes âgées en santé lors d’une tâche d’évocation lexicale orthographique et sémantique. Chaque tâche est divisée selon un critère « plus productive » et « moins productive ». Les âgés faiblement scolarisés produisent moins de mots que les âgés fortement scolarisés. De plus, la différence de mots produits entre le critère plus productif et moins productif est plus grande pour la tâche sémantique que pour la tâche orthographique. Du point de vue hémodynamique, les deux groupes ont des activations semblables, contredisant le phénomène HAROLD. De plus, les participants peu scolarisés tendent à activer de façon plus importante l’hémisphère gauche, peu importe la tâche ou la condition. Par contre, les activations varient selon la tâche et la condition dans le cas du groupe fortement scolarisé. / Normal aging is associated with cerebral reorganisation which can be influenced by many factors. For example, the theory cognitive reserve (Stern, 2002) is trying to explain how those factors can have an impact on the reorganization. However, some factors, such as educational level, are known to have an impact on cognitive performance. The aim of this dissertation is to study the effect of educational level in cerebral oxygenation of healthy older adults during both phonologic and semantic verbal fluency tasks. Each task is divided into two criteria: more productive and less productive. Behavioural data showed that less educated elderly generate fewer words than more educated ones for both tasks. Moreover, the differences between the number of words for the more productive criterion and the less productive one are higher for the semantic than for the phonologic task. NIRS data showed that both groups activated prefrontal cortex, without difference between them. In addition, less educated participants tend to have bigger activations in the left hemisphere regardless of the task and the criterion. On the other hand, higher educated participants’ activations vary according to the task and the criterion unlike the HAROLD model’s predictions.

Habituellement décrite dans les états maniaques chez des patients présentant un trouble bipolaire, la tachypsychie est définie comme une accélération de la pensée qui peut également être observée dans les états dépressifs mixtes. Pour évaluer les mécanismes psychopathologiques impliqués dans ce phénomène peu étudié, nous avons élaboré un auto-questionnaire, le Racing and Crowded Thoughts Questionnaire (RCTQ), et nous avons évalué ses propriétés psychométriques chez les sujets sains et chez les patients avec trouble bipolaire. Les mécanismes cognitifs ont été investigués par le biais d’approches temporelles et langagières. Nos résultats suggèrent que la tachypsychie est un phénomène composite présent même chez les sujets sains en cas d’instabilité mineure de l’humeur. Sur le plan cognitif, la tachypsychie a été associée à la présence d’anomalies lexico-sémantiques et exécutives relevées à des tâches de fluence verbale ainsi qu’à une accélération du passage du temps. / Racing thoughts have been traditionally described in manic states in patients with bipolar disorder. Recently, attention has been raised to this symptom in depressive episodes. In this thesis, we aimed at investigating the phenomenology of racing thoughts, a phenomenon that has been understudied so far, via a self-report questionnaire that we have developed – the Racing and Crowded Thoughts Questionnaire (RCTQ) -, in patients with bipolar disorder and in healthy individuals. From a cognitive standpoint, we assessed the cognitive underpinnings of racing thoughts via temporal and verbal fluency tasks. Our results suggest that racing thoughts are a multi-faceted phenomenon, that can be observed even in healthy individuals with mild affective instability. Importantly, our results show that racing thoughts are associated with lexico-semantic and executive abnormalities as well as with a feeling of faster than usual passage of time.

Submitted by Viviane Borim de Goes null (viviane_borim@hotmail.com) on 2018-03-19T11:32:37Z No. of bitstreams: 1 Dissertação_Versão Final_Viviane borim.pdf: 1660097 bytes, checksum: 5a7b7a20f668bfe605743bc3785b11ab (MD5) / Approved for entry into archive by Satie Tagara (satie@marilia.unesp.br) on 2018-03-19T15:00:17Z (GMT) No. of bitstreams: 1 goes_vb_me_mar.pdf: 1660097 bytes, checksum: 5a7b7a20f668bfe605743bc3785b11ab (MD5) / Made available in DSpace on 2018-03-19T15:00:17Z (GMT). No. of bitstreams: 1 goes_vb_me_mar.pdf: 1660097 bytes, checksum: 5a7b7a20f668bfe605743bc3785b11ab (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O processamento da informação auditiva é item fundamental para a função social, de modo a estar envolvido com domínios cognitivos como a função executiva, memória e linguagem. Isso permite ao indivíduo compreensão da linguagem e contribui posteriormente para expressão da mesma durante a comunicação. Nesse mesmo contexto, durante a situação comunicativa, a mesma é modulada pelo organismo por meio do funcionamento do sistema nervoso autônomo. Esse sistema também se relaciona com a cognição e esta, por sua vez, é fundamental para a aquisição e desenvolvimento da linguagem. Em tarefa executiva de linguagem ocorre o envolvimento dos domínios cognitivos acima citados. Dessa maneira, sugere-se que o processamento da informação auditiva se relaciona com o controle autonômico da frequência cardíaca e que tarefa executiva de linguagem pode modificar o desempenho dos potenciais relacionados a evento, de modo a representar maior esforço cognitivo, resultando em menor atividade da modulação parassimpática. Objetivos: Investigar a relação entre os potenciais relacionados a evento e a modulação parassimpática da frequência cardíaca antes e após tarefa executiva de linguagem e verificar os efeitos de tal tarefa. Método: Participaram desta pesquisa 42 mulheres saudáveis entre 18 e 30 anos de idade, com ensino médio completo, divididas em dois grupos: fonológico (n=21) e semântico (n=21). Após a colocação da cinta do cardiofrequencímetro na região do processo xifoide, a voluntária foi orientada a permanecer 10 minutos em repouso, sendo realizado os registros da frequência cardíaca. Em seguida, na primeira fase considerada pré-teste, foi iniciado o registro dos potenciais relacionados a evento com estimulação binaural nos parâmetros de frequência (1KHz/ 2KHz) paradigma oddball, concomitante ao registro da frequência cardíaca. Após, na segunda fase considerada teste, a tarefa executiva de linguagem foi realizada por meio do teste de fluência verbal fonológica para o grupo fonológico e teste de fluência verbal semântica para o grupo semântico. Na terceira fase considerada pós-teste, os registros dos potenciais relacionados a evento e da frequência cardíaca foram realizados utilizando os mesmos protocolos descritos na fase pré-teste. Resultados: Houve correlação da latência de P3 com o índice pNN50 no grupo fonológico pós-teste de fluência verbal fonológica (p=0,036). Na comparação dos potenciais relacionados a evento entre os momentos pré e pós-teste, foi observado diferença média e estatisticamente significante entre a latência de P3 após teste de fluência verbal fonológica, no grupo fonológico (p=0,020). Na comparação da modulação parassimpática da frequência cardíaca entre os momentos repouso, pré e pós-teste, houve diferença entre os índices RMSSD (p=0,007), pNN50 (p=0,035) e SD1 (p=0,007) após teste de fluência verbal fonológica, no grupo fonológico. Conclusão: Houve associação entre os potenciais relacionados a evento com a modulação parassimpática da frequência cardíaca após tarefa executiva de linguagem, em específico o teste de fluência verbal fonológica. Este teste, por sua vez, de forma significante, aumentou a latência de P3 e diminuiu a modulação parassimpática da frequência cardíaca. / The processing of auditory information is a fundamental element for the social function, involved with cognitive domains such as executive function, memory and language. This allows the individual to understand the language and subsequently contributes to its expression during communication. In the same context, during the communicative situation, it is modulated by the organism through the functioning of the autonomic nervous system. This system is also related to cognition and this, in turn, is fundamental for the acquisition and development of language. In the executive task of language, the involvement of the cognitive domains mentioned above occurs. Thus, it is suggested that the auditory information processing is related to the autonomic control of the heart rate and that the executive task of language can modify the performance of the event-related potentials, in order to represent greater cognitive effort, resulting in less activity of the parasympathetic modulation. Objective: To investigate the relationship between event-related potentials and the parasympathetic heart rate modulation before and after language task and verify the effects of such a task. Method: We analyzed 42 healthy women between 18 and 30 years of age with complete high school, were divided into two groups: phonological (n = 21) and semantic (n = 21). After placement of the cardiofrequency measuring strap in the xiphoid process region, the volunteer was instructed to remain at rest for 10 minutes, and heart rate records were performed. Then, in the first phase considered as a pre-test, the event-related potentials with binaural stimulation were started in the frequency parameters (1KHz/ 2KHz) oddball paradigm, concomitant to heart rate recording. After, the second phase, the executive task of language was performed using the phonological verbal fluency test for the phonological group and the semantic verbal fluency test for the semantic group. In the third phase considered post-test, the register the event-related potential and heart rate were performed using the same protocols described in the pre-test phase. Results: There was a correlation between the latency of P3 and the pNN50 index in the phonological group post-test of phonological verbal fluency (p = 0.036). In the comparison of the event-related potentials between the pre- and post-test moments, a mean and statistically significant difference between the P3 latency after phonological verbal fluency test was observed in the phonological group (p = 0.020). There was a difference between the RMSSD (p = 0.007), pNN50 (p = 0.035) and SD1 (p = 0.007) indices in the comparison of the parasympathetic heart rate modulation between the resting, pre and post-test moments phonological verbal fluency, in the phonological group. Conclusion: There was association between the event-related potentials with the parasympathetic heart rate modulation after executive language task, specifically the phonological verbal fluency test. This test, in turn, significantly increased P3 latency and decreased parasympathetic heart rate modulation.

INTRODUÇÃO: O teste de fluência verbal fonológica é uma tarefa neuropsicológica amplamente utilizada em estudos de neuroimagem funcional que analisam os circuitos neurais relevantes para a produção de linguagem. A maioria dos estudos que utilizam a RMf para analisar as áreas cerebrais de maior ativação durante a tarefa de fluência verbal é realizado na língua inglesa. Embora estudos anteriores tenham demonstrado que dependendo da língua falada possa ocorrer diferença de desempenho na tarefa de fluência verbal, ainda não está claro se esta diferença leva a mudanças do padrão de ativação cerebral. Há indícios na literatura que a ativação cerebral regional durante a tarefa de fluência verbal pode variar com o aumento de dificuldade da tarefa, sendo o cíngulo anterior a área cerebral que parece estar envolvida no processo de adaptação ao grau de dificuldade da tarefa. Estudos com sujeitos saudáveis demonstram também a influência de variáveis demográficas, como idade, escolaridade, gênero e classificação socioeconômica no desempenho na produção de palavras, com alguns estudos reportando maior ativação cortical nos homens em comparação às mulheres. OBJETIVOS: Avaliar os efeitos da variação do grau de dificuldade da tarefa de fluência verbal utilizando a técnica de ressonância magnética funcional. Analisar se há correlação entre os dados demográficos e o desempenho na tarefa de fluência verbal. Comparar o padrão de ativação cerebral entre os gêneros. MÉTODOS: Foram incluídos 21 voluntários saudáveis (12 homens), destros e falantes do português do Brasil como primeira língua. Foram colhidos dados sociodemográficos, neuropsicológicos e de desempenho dos voluntários. Comparamos os achados adquiridos através da técnica de ressonância magnética funcional durante a produção de palavras iniciadas com letras classificadas anteriormente como fáceis e difíceis para produzir palavras na língua portuguesa. As imagens foram adquiridas em aparelho de ressonância magnética de 1,5 T através de uma sequência de aquisição de imagens compressed epi que permite aos sujeitos produzirem as palavras apenas durante o período de silêncio do equipamento. As imagens foram analisadas através do software XBAM para os grupos e para a análise de correlação comportamental. RESULTADOS: A tarefa de fluência verbal engajou circuitos cerebrais incluindo córtex frontal medial e inferior esquerdo, putamen e tálamo (p<0,001). O aumento de dificuldade da tarefa de fluência verbal fonológica na língua portuguesa mostrou-se associado a uma diferença significativa de ativação apenas em uma região cerebral, o cerebelo (maior ativação durante a tarefa realizada com letras mais fáceis). Houve correlações significativas entre o desempenho na tarefa de fluência verbal fonológica na língua portuguesa e o grau de ativação do cíngulo anterior quando foram usadas letras difíceis para produção de palavras, mas não com letras fáceis. Não houve correlação significativa entre os dados demográficos (idade, escolaridade, gênero e classificação socioeconômica) e o desempenho durante a produção de palavras iniciadas com letras fáceis e com letras difíceis. Observamos maior ativação de cíngulo posterior e giro lingual nas mulheres em comparação aos homens durante a produção de palavras iniciadas com letras difíceis e interação positiva entre os gêneros e os graus de dificuldade na região de cíngulo anterior, demonstrando maior ativação do cíngulo anterior nos homens durante a produção de palavras iniciadas com letras difíceis. CONCLUSÃO: Apesar das diferenças lingüísticas, o padrão de ativação cerebral encontrado no nosso estudo foi consistente com o padrão verificado em outras línguas, com recrutamento de múltiplas áreas cerebrais durante a produção de palavras. Na língua portuguesa, assim como na língua inglesa, há indícios de que o aumento de dificuldade da tarefa está associado com maior engajamento de cíngulo anterior. Houve diferenças entre os gêneros em termos do engajamento de áreas cerebrais consideradas críticas para o desempenho na tarefa de fluência verbal fonológica, particularmente no cíngulo anterior / INTRODUCTION: Phonological verbal fluency is a neuropsychological test used in numerous functional neuroimaging studies to allow the assessment of the neural circuits relevant to language production. The majority of studies that use functional magnetic resonance imaging (fMRI) to analyze the cerebral areas with greater activation during the verbal fluency task have been carried out in English. Although there is evidence that the verbal fluency performance varies as a function of the spoken language, it is unclear if this difference is associated with differences in cerebral activation patterns. Added to that, there is neuroimaging evidence that patterns of regional cerebral activation during VF task may vary with task demand. In particular, the anterior cingulate cortex seems critical to the adaptation process to the level of difficult. Studies of healthy individuals have demonstrated the influence of demographic variables, such as age, level of education, gender and socio-economic status, on word production performance, and some authors have shown greater cortical activation in men than in women. OBJECTIVES: To use the fMRI technique to evaluate the effect of varying levels of difficult of verbal fluency task on the brain activation patterns in healthy subjects. To analyze whether there is a significant correlation between demographic variables and verbal fluency performance. To compare cerebral activation patterns between genders. METHODS: We recruited 21 (12 men) right-handed healthy volunteers, having Portuguese as their first language. Demographic, neuropsychological and behavioral data were collected. We compared fMRI data acquired during production of words beginning with letters classified as easy or hard for word production in Portuguese. Images were acquired in 1,5 T magnet through a clustered image acquisition sequence that allowed overt verbal responses to be made in the absence of scanner noise. Data were analyzed through XBAM software on group basis and for behavioral correlation. RESULTS: The phonological verbal fluency task engaged a network including the left inferior and middle frontal cortices, putamen and thalamus (p<0.001). The hard condition was associated with greater anterior cingulate activation than the easy condition when associated with the performance, as previously demonstrated in studies carried out with English speaking subjects. Increased phonological verbal fluency task demand in Portuguese was associated with activation differences in only one brain region, namely the cerebellum (in the direction of greater activation during performance of the task with easy letters). There were significant correlations between phonological verbal fluency task performance in Portuguese and the intensity of anterior cingulate activation, when hard letters to produce words were used (but not with easy letters). There were no significant correlations between demographic variables and the performance during production of words beginning with easy or difficult letters. There was greater activation of the posterior cingulate cortex during the production of words beginning with the difficult letters in women than in men. There was also a significantly positive interaction between gender and level of difficult in anterior cingulate cortex, with men showing greater activation of this brain region during the word production beginning with difficult letters relative to women. CONCLUSIONS: Despite grammatical differences, the patterns of cortical activations observed in our study were in accordance with fMRI studies of phonological verbal fluency task carried out in other languages, with recruitment of a set of distributed cerebral areas during the word production. There is evidence that increased task demand is associated with greater engagement of the anterior cingulate cortex in Portuguese, similarly to the patterns previously observed in English. There were gender differences in regard to the engagement of brain regions seen as critical to verbal fluency performance, particularly in the anterior cingulate cortex

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has received more attention in recent years as a treatment option for regulating the symptoms of Parkinson's disease. Previous studies of DBS documented consistent improvements in motor function but more variability in speech outcomes. In the present study, six participants diagnosed with idiopathic Parkinson's disease who reported worsened speech with stimulation were recorded performing speech acoustic tasks with the stimulators on, and again with the stimulators off. Improvements were noted for most participants in measurements of formant slopes, long term average spectrum (LTAS) of a sustained vowel, and spirantization with stimulation on. Stimulation negatively affected most participants' vowel space area, verbal fluency, sequential motion rate, and LTAS while reading and describing a picture. Measures of stop gap duration, alternating motion rate, and voice onset time were within normal limits for most participants across both stimulation conditions.

There are currently no Swedish norms for the bedside version of the Western Aphasia Battery (B-WAB-R) and the Cognitive Linguistic Quick Test (CLQT). It is unknown whether age, gender, and education influence performance in a Swedish context. Verbal fluency tests measure language and cognition, but semantic and phonemic versions are associated with separate cognitive processes. The aim was to evaluate how non-impaired adults performed on Swedish translations of B-WAB-R and CLQT, and the verbal fluency tests FAS and Animal Naming. Fifty-two participants without linguistic or cognitive impairments aged 21–88 were recruited. Potential differences in performance depending on age, gender, and education were analysed, and how performance on FAS and Animal Naming related to CLQT, and B-WAB-R performance. Performance did not differ depending on gender or education. Some scores fell below previous CLQT cut-offs for mild cognitive impairment. Participants aged 30–49 had better performance than older groups on Animal Naming and the CLQT domains Attention, Executive Functions and Language, and better performance than the youngest group on Attention. Animal Naming was weakly related to both language and cognitive measures. FAS was not related to any other measure. The small and unequally distributed sample limits the generalizability of the results. More research is needed to determine how age and education influence performance on CLQT and B-WAB-R in Sweden. More research is also needed to determine whether phonemic and semantic verbal fluency tests measure the same cognitive processes. / Det finns för närvarande ingen svensk normering för bedside versionen av Western Aphasia Battery (B-WAB-R) och Cognitive Linguistic Quick Test (CLQT). Det är okänt huruvida ålder, kön och utbildning påverkar prestationen i en svensk kontext.Ordflödestest mäter språk och kognition, men semantiska och fonetiska versioner är associerade med skilda kognitiva processer. Syftet var att utvärdera hur icke-nedsatta vuxna presterade på svenska översättningar av B-WAB-R och CLQT, samt ordflödestesten FAS och Djur. Femtiotvå deltagare utan språkliga eller kognitiva nedsättningar i åldrarna 21–88 rekryterades. Potentiella prestationsskillnader beroende på ålder, kön och utbildning analyserades, samt hur prestation på FAS och Djur relaterade till prestation på CLQT och B-WAB-R. Det fanns inga skillnader i prestation beroende på kön eller utbildning. Några poäng hamnade under tidigare satta CLQT gränsvärden för lindrig kognitiv nedsättning. De i åldern 30–49 hade bättre prestation än äldre grupper på Djur och CLQT domänerna Uppmärksamhet, Exekutiv Funktion och Språk, samt bättre prestation än den yngsta gruppen på Uppmärksamhet. Djur var svagt relaterad till både språkliga och kognitiva mått. FAS relaterade inte till några mått. Det lilla och ojämnt fördelade urvalet begränsar resultatens generaliserbarhet. Mer forskning behövs för att avgöra hur ålder och utbildning påverkar prestation på B-WAB-R och CLQT i Sverige. Mer forskning behövs även för att avgöra om fonetiska och semantiska ordflödestest mäter samma kognitiva processer.

Dans le cadre de l’évaluation pré-chirurgicale de patients épileptiques, il est impératif de déterminer la spécialisation hémisphérique du langage, ainsi que de localiser les aires du langage au sein de cet hémisphère. De nouvelles méthodes d’évaluation non- invasives doivent être mises au point afin de diminuer les risques associés aux méthodes plus invasives telles que le test à l’amobarbital intracarotidien (TAI). L’objectif principal de cette thèse est donc de développer un protocole d’évaluation pré-chirurgicale alternatif et non-invasif à l’aide de la magnétoencéphalographie (MEG) pour la latéralisation et la localisation du langage, incluant la mémoire verbale qui serait éventuellement accessible à une population pédiatrique francophone épileptique. L’article 1 présente une recension de la littérature résumant les différentes études en MEG ayant pour objectif l’évaluation pré-chirurgicale du langage. Trente-sept articles en MEG ont été analysés pour déterminer quelles tâches permettaient d’obtenir les meilleurs résultats de latéralisation intrahémisphérique et de localisation du langage pour l’évaluation du langage réceptif et expressif chez des sujets neurologiquement sains et épileptiques. Parmi les tests retenus, l’épreuve de reconnaissance de mots permet d’évaluer le langage réceptif et la mémoire verbale, tandis que des épreuves de fluence verbale telles que la génération de verbes permettent d’évaluer le langage expressif de façon à obtenir de très bons résultats. L’article 2 a permis de valider un protocole auprès de sujets neurologiquement sains à l’aide des épreuves identifiées dans l’article 1. Le protocole utilisé comprend une tâche de langage réceptif et de mémoire verbale (une épreuve de reconnaissance de mots) et une tâche de langage expressif (une épreuve de fluence verbale). Suite à la validation du protocole à l’aide d’analyses par composantes principales, les épreuves ont été administrées à un groupe de patients épileptiques. Les index de latéralité et les analyses de sources i révèlent que la MEG permet de localiser et de latéraliser les fonctions langagières et pourrait donc être utilisée comme méthode d'évaluation du langage lors de l'évaluation pré- chirurgicale auprès de patients épileptiques. Toutefois, alors que l’épreuve de mémoire verbale a permis d’obtenir les meilleurs résultats auprès de l’ensemble des participants, l’épreuve de fluence verbale n’a fourni des informations supplémentaires que chez un seul patient et chez aucun participant neurologiquement sain. En résumé, les deux articles de cette thèse démontrent le potentiel clinique de la MEG pour l’évaluation pré-chirurgicale de patients souffrant d’une épilepsie réfractaire. / It is imperative to determine hemispheric dominance of language and to localize language areas in this hemisphere as part of the presurgical evaluation of epileptic patients. New non-invasive evaluation methods should be developed to reduce the risks associated with more invasive methods such as the intracarotid sodium amobarbital procedure (ISAP). The main objective of this dissertation is to develop an alternative non-invasive presurgical evaluation protocol using magnetoencephalography (MEG) to determine the lateralisation and localization of language and verbal memory that would eventually be accessible to a French-speaking paediatric population suffering from epilepsy. Article 1 is a literature review summarizing MEG studies on the presurgical evaluation of language. Thirty-seven articles were analyzed to determine which tasks allow to obtain the best results with regards to language lateralization and localization with MEG in the assessment of receptive and expressive language in neurologically healthy individuals as well as epileptic patients. We conclude that the word recognition task is well suited to assess receptive language and verbal memory, while a verbal fluency task, such as the verb generation task allows the assessment of expressive language with very good results. Article 2 allowed the validation of a language protocol with neurological healthy participants based on the tasks identified in article 1. The protocol included a task evaluating receptive language functions and verbal memory (word recognition task) and a task evaluation expressive language (verbal fluency). After having validated the tasks using principal component analysis, they were administered to a group of patients with epilepsy. Laterality findings and source analysis showed that MEG can be used to lateralize and localize language and could therefore be used in the presurgical assessment of patients with epilepsy. However, the verbal fluency task, when compared to the verbal memory task, provided additional information for only one patient and in none of the neurologically healthy participants. In summary, the two articles of this dissertation demonstrate the clinical potential of MEG for the presurgical evaluation of patients with refractory epilepsy.

La symptomatologie non motrice de la maladie de Parkinson s’accompagne fréquemment d’un défaut de contrôle cognitif. Le contrôle cognitif faisant référence à un ensemble de processus facilitant le traitement de l’information et la production de comportements adaptés, son altération impactera de très nombreuses capacités cognitives. Parmi ces capacités, nous nous intéresserons plus spécifiquement, d’une part, à la production orale de mots évaluée à travers les tests de fluences verbales et, d’autre part, aux processus favorisant la production d’actions intentionnelles en situation motivée comme évaluée par la Simon Task motivée. Par notre première étude nous remettrons en question l’hypothèse d’un défaut de contrôle cognitif comme origine principale de la réduction des performances aux tests de fluences verbales à la suite de la stimulation cérébrale profonde du noyau subthalamique. En effet, nous n’avons pas mis en évidence de relation entre cette altération et une modification de l’activité métabolique des régions frontales supportant le contrôle cognitif, ou une modification des performances à d’autres tests nécessitant un contrôle cognitif efficient. Les travaux suivant, portant sur le contrôle des actions motivées démontrent, d’une part, que la production d’actions guidées, non pas par des tendances d’actions impulsives, mais par des tendances d’actions en accord avec les intentions, est plus ardue lorsqu’une récompense financière est mise en jeu. D’autre part, le traitement de la maladie de Parkinson, aussi bien par dopathérapie que par stimulation cérébrale profonde du noyau sous-thalamique module le fonctionnement des processus impliqués, suggérant un rôle particulier des noyaux gris centraux. Nous discuterons des processus cognitifs et neuronaux impliqués et proposerons des perspectives de recherche aussi bien neuroscientifiques que cliniques. / The nonmotor symptoms of Parkinson’s disease frequently include a cognitive control deficit. Cognitive control refers to a set of processes that promote information processing and the production of appropriate behaviours, so its impairment can have an impact on a wide range of cognitive abilities. We focused on just two of these abilities: oral word production, as assessed with phonemic and semantic verbal fluency tests; and cognitive action control in an incentive context, as assessed with a rewarded Simon Task. In our first study, we questioned the hypothesis that the reduction in verbal fluency performances observed following surgery for subthalamic nucleus deep-brain stimulation is mainly due to a cognitive control deficit. Results failed to reveal a relationship between this reduction and either modified metabolic activity in the frontal regions subtending cognitive control or modified performances on other tests requiring efficient cognitive control. In our second and third studies, investigating cognitive action control in an incentive context, we showed that the production of intention-driven actions, as opposed to impulsive ones, is more difficult when a monetary reward is at stake. We also demonstrated that treatment for Parkinson’s disease, whether it takes the form of dopaminergic medication or subthalamic stimulation, modulates the functioning of these processes, suggesting that the basal ganglia have a role in them. We discuss the cognitive and neural processes involved and outline future avenues for both neuroscientific and clinical research.

Le maintien de performances cognitives optimales au cours du vieillissement a été associé à des changements adaptatifs au niveau de l’activité cérébrale relative à diverses habiletés qui tendent à décliner avec l’âge. Peu d’études ont toutefois évalué cette réorganisation neurofonctionnelle dans le cadre des habiletés de communication, notamment en ce qui concerne le langage expressif. Or, considérant que plusieurs composantes langagières demeurent généralement intègres chez les aînés, il s’avère nécessaire d’explorer davantage les mécanismes cérébraux sous-jacents afin de mieux cerner les déterminants du vieillissement cognitif réussi. L’objectif de la présente thèse est d’examiner en détail les effets de l’âge sur les patrons d’activations et les interactions fonctionnelles entre les substrats neuraux contribuant aux habiletés de communication expressive. Deux études en neuroimagerie fonctionnelle, ayant recours à des approches méthodologiques distinctes, ont ainsi été menées à l’aide d’un paradigme mixte novateur et d’une tâche auto-rythmée d’évocation lexicale sémantique et orthographique, effectuée par des participants jeunes et âgés présentant plusieurs années de scolarisation. S’intéressant spécifiquement aux patrons d’activations associés à un rendement élevé à cette tâche, la première étude révèle que le maintien des habiletés d’évocation lexicale lors du vieillissement s’accompagne de changements neurofonctionnels superficiels chez les adultes âgés performants. Par contre, la seconde étude indique que les interactions fonctionnelles entre les régions corticales contribuant aux productions lexicales déclinent considérablement avec l’âge, sans qu’il y ait toutefois d’impact au plan comportemental. Cet effet du vieillissement sur l’intégration fonctionnelle du réseau de l’évocation sémantique et orthographique est aussi exacerbé par la difficulté de la tâche, ce qui s’exprime par des perturbations locales de la connectivité fonctionnelle. Somme toute, cette thèse démontre qu’une réorganisation neurofonctionnelle afin de maintenir les habiletés d’évocation lexicale au cours du vieillissement s’avère superflue chez les adultes âgés instruits et performants, et ce, malgré une diminution des interactions fonctionnelles au sein des réseaux corticaux sous-jacents. Ces résultats reflètent possiblement une perte d’efficience neurale avec l’âge, toutefois insuffisante pour avoir un impact comportemental chez des individus bénéficiant de facteurs de protection susceptibles de favoriser le vieillissement réussi, ce qui est discuté à la lumière du concept de réserve cognitive. / The maintenance of optimal cognitive performance in aging has been associated with adaptive changes in cerebral activation patterns for various abilities that tend to decline with age. Yet, few studies have investigated this neurofunctional reorganization based on communication abilities, particularly with regard to the expressive side of language. Considering that a number of language components usually remain well preserved in older adults, it is, however, necessary to further explore the underlying cerebral mechanisms to better understand the determinants of successful cognitive aging. The objective of this thesis is to examine in detail the effects of aging on activation patterns and functional interactions among neural substrates contributing to expressive communication abilities. Two functional neuroimaging studies, using distinct methodological approaches, have been conducted by means of an innovative mixed design and an overt self-paced semantic and orthographic verbal fluency task, performed by well-educated young and older adults. Specifically focusing of cerebral activation patterns associated with high levels of verbal fluency performance, the first study shows that the relative preservation of lexical speech production abilities in aging is characterized by marginal neurofunctional changes in high-performing older adults. Yet, the second study indicates that functional interactions between cortical areas contributing to speech productions significantly decrease with age, without, however, having an impact at the behavioral level. In addition, this effect of aging on the functional integration of the network engaged during semantic and orthographic verbal fluency was found to be exacerbated by task demands, which is expressed by local functional connectivity disruptions. In sum, this thesis demonstrates that a neurofunctional reorganization to maintain lexical speech production abilities in aging is unnecessary in well-educated and high-performing older adults, despite an age-related decrease in functional networks integration. These results may reflect a loss of neural efficiency with age, although insufficient to have behavioral outcomes in individuals who benefited from protective factors known to promote successful aging, which is discussed in light of the concept of cognitive reserve.

Ce travail a porté sur les remaniements corticaux précoces des circuits moteurs et extramoteurs dans la SLA grâce à l’étude des activations IRMf issues de tâches motrices et cognitives. La première partie de nos travaux nous a permis de montrer grâce des tâches simples d’activation motrice en IRMf (1) qu’alors que les patients SLA présentaient un déficit moteur discret, une augmentation des activations corticales est apparue dans les aires sensorimotrices bilatérales du cerveau. (2) Ces modifications précoces de l’activité neuronale étaient corrélées à la latéralisation du déficit moteur du membre ou la prédominance manuelle et surtout, (3) au taux de progression de la maladie à un an et à la survie, suggérant que ce remaniement de l’activité qui correspond probablement à de la plasticité cérébrale a des implications fonctionnelles. Enfin, (4) ce phénomène apparaissait actif puisqu’il s’est poursuivi pendant au moins onze mois. Dans la deuxième partie, nous avons montré lors d’une tâche de fluence verbale silencieuse que (1) les SLA présentaient une suractivation initiale des aires dévolues au processus sémantique avec un renforcement de la connectivité fonctionnelle entre les réseaux (CFR). (2) Au bout de onze mois et alors que l’atteinte des fluences était stable, ce phénomène de compensation s’épuisait avec une diminution conjointe de l’activation des réseaux et de la CFR. La tâche de 2-Back, réalisée alors que les patients ne présentaient pas d’atteinte de la mémoire de travail lors des tests psychométriques, nous a permis de montrer en outre que certains circuits non-moteurs se réorganisaient très précocement chez les patients, alors même qu’ils étaient asymptomatiques / In this work we used motor and cognitive tasks in an fMRI study to explore the early cortical reorganizations of the motor and extra-motor circuits in ALS patients. In a first part, using a simple motor task, we demonstrated (1) that increased cortical BOLD signal changes occurred in specific regions of the brain of ALS patients when their motor deficit was still moderate, and that this early signal changes correlated with (2) the lateralisation of the motor deficit or hand predominance and, more importantly, (3) with the rate of disease progression at one year and survival time, suggesting that modulations of cerebral activity in ALS may have functional implications. Furthermore, (4) this brain plasticity was maintained with time and disease progression during at least eleven months. In a second part, we demonstrated during a silent verbal fluency task (1) that ALS patients presented initially an increased cortical activation of areas devolved to the semantic process with an intensification of the functional network connectivity (FNC). (2) After eleven months and while their performance in tests of verbal fluency was stable, this cerebral compensation ran out with a decrease of the previous cerebral activations and the FNC. A N-back working memory paradigm, realized while the patients did not present any deficit of their working memory, allowed us to show that certain non-motor circuits were reorganized prematurely while patients were still asymptomatic