Several studies have focused on the contribution of the right hemisphere brain to the emotional aspects of communication, raising evidence that it is specialized in the emotional processing of faces. Right hemisphere brain damage (RHBD) may cause disturbances in the function mentioned, affecting social interactions since they depend on facial emotion recognition. This research aimed to contribute to the study of the possible impairment in the ability to identify facial expressions in 4 RHBD patients in order to elucidate whether those interfere with the performance of two emotion recognition instruments expressed by faces images. From a comparison between the RHBD group, 4 patients with left hemisphere brain damage (LHBD) and 8 subjects in the control group, we found 22 statistically significant or borderline statistical associations results (p≅0,05) only to the stimuli of the instrument Facial Expression Brazilian Task (FERBT), including the analysis of the emotional valences between LHBD and RHBD groups. Of these, 13 showed superiority of the control group in relation to clinical groups, and 9 showed superiority the LHBD group compared to the RHBD group. From this study, we can infer that FERBT is more congruent in relation to Emotion Recognition Index (ERI) concerning the hypothesis of brain asymmetry in facial expression recognition. The results of FERBT partially agrees with the hypothesis of emotional valence, since significant differences between clinical groups were found, favoring the LHBD group to the sum of emotion scores of negative valence at 500 milliseconds (ms), 1 second (s) and overall score of FERBT, adding up all the emotions in different times. However, it should be noted that borderline statistical associations differences favoring the LHBD group were found only for the emotion of fear (200ms and the total time) and anger (total time) with no significant differences for emotions of positive valence. This study helped to assess neuropsychological deficits after right hemisphere brain damage, since there is a significant gap in this diagnostic area. Through research, we can improve our knowledge about impairments caused by right hemisphere lesion by increasingly developing accurate assessment techniques and rehabilitation methods. / Vários estudos têm enfocado a contribuição do hemisfério cerebral direito para os aspectos emocionais da comunicação, levantando evidências de que o mesmo é especializado no processamento emocional de faces. Lesões de hemisfério direito (LHD) podem acarretar perturbações na função descrita anteriormente, prejudicando as interações sociais, uma vez que estas dependem do reconhecimento de emoções na modalidade facial. A presente pesquisa teve como finalidade contribuir para o estudo dos possíveis comprometimentos na capacidade de identificar expressões faciais em 4 pacientes LHD, buscando elucidar se àqueles acabam interferindo no desempenho de 2 instrumentos de reconhecimento de emoções expressas por imagens de faces. A partir de um comparativo entre o grupo LHD, 4 indivíduos com lesão de hemisfério esquerdo (LHE) e 8 sujeitos controle, foram encontrados 22 resultados com significância estatística ou associações estatísticas limítrofes (p≅0,05) somente para os estímulos do instrumento Facial Expression Brazilian Task (FERBT), incluindo análise da valência emocional entre grupos LHE e LHD. Destes, 13 mostraram superioridade do grupo controle em relação aos grupos clínicos e 9 mostraram superioridade de grupo LHE em relação ao grupo LHD. Infere-se a partir do presente estudo que o FERBT apresenta maior congruência, em relação ao Emotion Recognition Index (ERI), com a hipótese da assimetria cerebral no reconhecimento de expressões faciais. Os resultados do FERBT concordam parcialmente com a hipótese da valência emocional, uma vez que foram encontradas diferenças relevantes entre grupos clínicos, favorecendo o grupo LHE, para o somatório das pontuações de emoções de valência negativa nos tempos de 500 milissegundos (ms), 1 segundo (s) e pontuação geral do FERBT somando-se todas as emoções dos diferentes tempos. Contudo, deve-se ressaltar que associações estatísticas limítrofes, favorecendo o grupo LHE, foram encontradas apenas para a emoção de medo (200ms e total dos tempos) e raiva (total dos tempos), não havendo diferenças significativas para emoções de valência positiva. O presente estudo contribuiu para a avaliação de déficits neuropsicológicos após lesão direita, visto que há importante lacuna nessa área de diagnóstico neuropsicológico. Através da pesquisa, poderemos aprimorar nosso conhecimento sobre as disfunções ocasionadas pela lesão de hemisfério direito, desenvolvendo técnicas cada vez mais precisas de avaliação e métodos de reabilitação.

La négligence spatiale unilatérale (NSU) est une affection neurologique fréquemment observée après une lésion de l'hémisphère cérébral droit. Les patients ne vont plus être en mesure de prendre en compte les stimuli présentés dans l'hémi-espace gauche. La NSU participe à l'aggravation du handicap des patients, par la réduction des possibilités en rééducation motrice et cognitive à la phase aigue d'un accident vasculaire comme sur le long terme. L'identification des facteurs prédictifs de sa chronicité pourrait permettre une meilleure prise en charge clinique de ces patients. Nous avons étudié les altérations des connexions anatomiques observées en IRM de diffusion sous-tendant la persistance de la NSU. Nos résultats démontrent qu'en plus d'un dysfonctionnement fronto-pariétal hémisphérique droit, la persistance de ce syndrome serait associée à une déconnexion interhémisphérique. L'hémisphère gauche isolé ne serait pas en mesure de compenser les déficits des patients. La récupération devrait s'effectuer par une amélioration dans les capacités d'échange des informations entre les deux hémisphères, notamment dans les régions postérieures pariétales et occipitales. Nous nous sommes intéressés à tester cette hypothèse par le biais d'une méthode de rééducation, l'adaptation prismatique (AP). Il s'agit d'une thérapie dont les effets sur la sémiologie des patients sont remarquables. Nos résultats suggèrent que l'amélioration de la NSU pourrait s'observer par le recrutement du réseau fronto-ponto-cérébelleux. Les régions frontales gauches seraient un relais anatomique entre le cervelet droit et le réseau fronto-pariétal gauche / Unilateral spatial neglect is a frequent neurological condition after right hemisphere damage. Patients behave as if objects on their left did not exist anymore. The presence of neglect has negative prognostic value for functional recovery in the acute and chronic phases after a stroke. Finding predictors of persistent neglect would permit to adapt rehabilitation procedures. We used diffusion MRI to define the state of anatomical connections in neglect and their predictor value for neglect persistence. Our results revealed that, together with right intra-hemispheric fronto-parietal disconnections, persistence of neglect is associated with inter-hemispheric disconnection. We concluded that an isolated left hemisphere may fail to compensate neglect because it cannot take into account left-sided objects. Recovery of neglect would instead occur thanks to the sharing of visual information between the two hemispheres, notably in posterior parietal and occipital cortices. We tested this hypothesis by using prism adaptation (PA) therapy. PA is a non-invasive and convenient technique to rehabilitate neglect. We showed that patients with damaged fronto-ponto-cerebellar pathways did not benefit from PA. This finding strongly suggests that PA can ameliorate signs of neglect by improving inter-hemispheric communication through enhanced activity of these connections. Left frontal areas may constitute the anatomical link between the right cerebellum and the left fronto-parietal network. Thus, connectional anatomy can help predict both neglect recovery and the quality of its response to rehabilitation therapies

Un aspect fondamental du contrôle attentionnel réside dans la capacité du sujet à anticiper l’apparition d’un stimulus afin de rendre son traitement plus rapide et plus efficace. L'attention préparatoire (AP) est la capacité de moduler (rehausser) l’intensité de l’attention dirigée vers un stimulus sélectionné avant son apparition, en empêchant que le sujet soit distrait par une information non pertinente. Certaines études soutiennent que l’AP est latéralisée dans l’hémisphère droit (HD) alors que d’autres suggèrent que les deux hémisphères, l’hémisphère gauche (HG) et l’HD, sont impliqués dans la modulation de l’AP. L’objectif de cette thèse est d’analyser le rôle joué par chaque hémisphère cérébral dans la modulation de l’AP dirigée vers une localisation de l’espace. Nous avons développé une version latéralisée du test APT (pour Attentional Preparatory Test, proposé par LaBerge, Auclair & Siéroff, 2000), le LAPT (Lateralized Attentional Preparatory Test). L’APT permet de mesurer la capacité des sujets à moduler leur AP vers la localisation d’une cible lorsque la probabilité d'un distracteur varie selon plusieurs blocs d’essais. Dans l’APT, le temps de réponse augmentait lorsque la probabilité d’apparition d’un distracteur dans la phase préparatoire antérieure à la présentation de la cible augmentait, ce qui montre que l’AP est modulée par des évènements antérieurs au traitement de la cible. Nous avons créé le LAPT en utilisant la méthode de présentation en champ visuel divisé dans laquelle les stimuli peuvent apparaître dans le champ visuel gauche (CVG) ou dans le champ visuel droit (CVD). Les différences de performances entre champs visuels nous donnent des indications sur les stratégies de traitement des deux hémisphères (CVD/HG vs CVG/HD). Dans une série d’études, nous avons montré que la modulation de l’AP en fonction de la probabilité attendue d’un événement diffère dans chaque champ visuel/hémisphère en fonction de la configuration de la tâche. Dans le CVD/HG, l’AP est modulée par la probabilité des événements distracteurs, surtout quand cette probabilité est explicite. De plus, l’HG semble tenir un rôle crucial dans la modulation de l’AP quand la cible et le distracteur sont difficiles à discriminer. Dans le CVG/HD, l’AP est modulée par la probabilité temporelle des événements et dépendrait du délai le plus probable dans lequel la cible est attendue, mais seulement lorsque la discrimination entre la cible et le distracteur est plus facile. Enfin, nos résultats suggèrent que les différences entre le CVD/LH et le CVG/RH lors de cette modulation attentionnelle se mettent en place à un niveau perceptif du traitement de l’information car ils sont indépendants de la main utilisée pour répondre et donc des processus requis au niveau de la programmation motrice. L’ensemble de ces résultats suggère que chaque hémisphère utilise une stratégie différente pour moduler l’AP lorsqu’elle est dirigée vers une localisation de l’espace. / A crucial aspect of attentional control is the capacity of anticipating a stimulus appearance in order to improve the speed and effectiveness of its subsequent processing. Preparatory attention (PA) is the ability to modulate (enhance) the intensity of attention directed to a selected stimulus prior to its occurrence, preventing subjects from being distracted by interfering stimuli. Some studies propose that PA is lateralized to the right hemisphere (RH) while others suggest that both the left hemisphere (LH) and the RH participate in the modulation of PA. The aim of the present thesis was to examine the role of each brain hemisphere in the modulation of PA directed to a spatial location. We developed a lateralized version of the Attentional Preparatory Test, (APT, proposed par LaBerge, Auclair & Siéroff, 2000), named the Lateralized APT or LAPT. The APT measures the ability of subjects to modulate PA directed to a target location when the probability of a distractor occurrence varies across several blocks of trials. In the APT, the response times increased as the probability of a distractor appearing in the preparatory phase preceding the target presentation increased, showing that PA is modulated by the events occurring prior to the target appearance. We developed the LAPT using the divided visual field paradigm in which stimuli can occur in the left (LVF) or the right (RVF) visual fields. The visual field differences in subjects’ performance are assumed to reflect differences in the processing strategies of both hemispheres (RVF/LH vs LVF/RH). In a series of studies we showed that the modulation of PA by the expected probability of events was different in each visual field/hemisphere, depending on task configuration. In the RVF/LH, PA is modulated by the expected probability of distractor events, especially when this probability is explicit. In addition, the LH seems to play a crucial role in modulating PA when the target and the distractor are hard to discriminate. In the LVF/RH, PA is modulated by the temporal probability of events and may depend on the most probable delay in which the target is expected, but only when the discrimination between the target and the distractor is easy. Most importantly, our findings suggest that the differences between RVF/LH and LVF/RH in the modulation of PA take place at the perceptual level of processing because they are independent of the hand use in executing the response, thus also independent of the processes taking place at the motor programming level. Taken together our results, they suggest that each hemisphere uses a different strategy to modulate PA when directed to a spatial location.

The study of lateralisation has taken several forms ranging from investigating morphological asymmetries to research on lateralised motor and perceptual functions with many studies successfully evidencing lateralisation in a variety of species. This study, featuring three species (olive baboons, rhesus macaques, and spotted hyaenas) investigated visual field biases with the aim of determining whether emotional valence underpins these biases whilst also considering the influence of a number of other factors such as emotional intensity, age, sex, rank, and, for the first time, oestrus cycles (olive baboons only). This study aimed to establish whether Campbell’s (1982) Right Hemisphere Hypothesis or Silberman & Weingartner’s (1986) Valence Hypothesis offered the more valid theory for the lateralisation of emotion by considering interactions across the full spectrum of emotion – a question the almost exclusive investigation of negatively affective scenarios by previous studies has been unable to answer. Furthermore, this study provided a new methodology for investigating behavioural lateralisation by suggesting that separating the visual spectrum into five fields (extreme left, mid left, centre, mid right and extreme right) allows a more accurate insight into the lateralisation of visual perception than the traditional hemifield model. Finally, a more conservative method is proposed for analysing behavioural data in future studies from this field and suggests that these methods provide a more accurate representation of the lateralisation of emotion than those previously employed. A population-level left side bias was found for the spotted hyaenas, thus providing the first evidence of significantly lateralised behaviour in a large carnivore and, for this species at least, lending some support to Campbell’s (1982) Right Hemisphere hypothesis but as population-level biases were not found for either of the other species it may be premature to suggest this support is unequivocal. Significant age effects were found in two species as adult olive baboons and spotted hyaenas were both found to express significant left side biases. Spotted hyaenas were also found to express significant left side biases for females, dominant individuals, high intensity interactions, and sexual valence interactions whilst olive baboons expressed a significant left side bias during negative valence behaviours but no significant lateral biases were found in any context for rhesus macaques. In olive baboons behaviours performed by males and those of a low intensity were found to occur more frequently in the mid and central visual fields and neutral valence behaviours were less occurrent in the extreme visual fields whilst in spotted hyaenas sexual, positive and negative valence behaviours were significantly less centralised than neutral valence behaviours. Non-oestrus adult female olive baboons were significantly more strongly lateralised than in-oestrus females, thus suggesting an influence of sex hormones upon lateralisation that may also have been apparent from the hyaena data, particularly regarding the significant lateral biases observed for females and dominant individuals. Finally, this thesis discusses a number of methodological issues that were encountered during this study and provides recommendations for future research in this field. Namely, this thesis provides an updated method for calculating laterality bias that is much more suitable for species with binocular vision and details a novel method of assessing visual field preferences by considering central and peripheral visual fields as separate entities. Furthermore, this thesis suggests that the weighted method designed and implemented for this study provides a much more accurate methodological foundation for analyses which avoids the caveats that may have affected previous research and thus provides a considerably more robust template that should be encouraged for any similar subsequent studies.

本文透過操弄雙字詞詞首的語意(sense)多寡和左右視野，試圖探討中文雙字詞的語意表徵和左右大腦對於多意詞(polysemy)的處理機制。實驗一顯示的左右腦結果和Pylkkänen等人在2006年的MEG研究相似，也就是左腦的多意詞促進效果，支持多意詞單一表徵的型態；然而，右腦卻呈現多意詞抑制的效果。這樣的現象產生兩者可能解釋：(1) 右腦還是屬於單一語意表徵，但由於右半腦處理語意的特性，導致和左腦得到不同的結果；(2)右腦的結果是來自於右腦屬於語意多重表徵(separate entries)的因素。為了要釐清這些說法，實驗二進一步的改變作業深度，讓受試者做詞類判斷作業，企圖讓受試者進行比較深層的語意處理。實驗二結果顯示，在改變作業深度之後，我們的確得到右腦語意促進效果，所以證明右腦的語意屬於單一表徵，在比較深層作業處理階段，因為左右腦處理語意的特性，使得右腦有機會呈現實驗預期的結果。另外，在動詞、名詞事後分析的結果中，我們也發現動詞、名詞的語意效果在大腦有不同的分布區位。名詞的語意效果分布在大腦中間偏後的位置；動詞則是主要分布在大腦前額一帶 總結以上發現，本研究的發現支持過去學者所提出的多意詞單一表徵的說法；第二、本研究對左右半腦處理語意特性，也符合過去的假設，也就是左腦擅長主要、細微的辨識，右腦則擅長維持次要、普遍語意。第三、本研究額外的發現是，動詞、名詞的語意效果在大腦有不同的分布，意味著不同的詞類在大腦可能有不同的表徵。 / Acknowledgements …………………………………………………………iv Tables…………….……………………………………………………………ix Figures …………………………………………………………………………x Chinese Abstract …………………………………………………………xii English Abstract ………………………………………………………xiii CHAPTER 1. INTRODUCTION ……………………………………………………..……1 1.1 What are senses? Homonymy vs. Polysemy …………………….1 1.2 English words vs. Chinese compounds ………………………….3 1.3 Hemispheric processing of semantic ambiguity ……………4 2. REVIEW OF RELATED PSYCHOLINGUISTIC RESEARCH ………………6 2.1 Neighborhood size effect in English …………………………6 2.2 Neighborhood frequency effect …………………………….……9 2.3 Event-related potentials (ERPs) vs. neighborhood size effect....11 2.3.1 Event-related potentials ………………………………….11 2.3.2 The advantages of electrophysiological techniques …12 2.3.3 Language-related ERP components ……………………….…12 2.3.4 The neighborhood size effect and. ERPs ……………..14 2.4 Neighborhood size effect in Chinese ……………………….16 2.5 Lexical ambiguity in English—homonymy vs. polysemy……… 22 2.5.1 Mixed results of ambiguity effects ………………………23 2.5.2 Polysemy—separate entries or single entry? …………25 2.5.3Some evidence for single entry hypothesis of senses…27 2.6 Lexical ambiguity in Chinese …………………….……………26 2.7 Hemispheric asymmetry in lexicon processing ……………33 3. EXPERIMENT 1 ………………………………………………………………38 3.1 Experiment 1... ..……………………………………….….....39 3.1.1 Participants …………………………………………………………39 3.1.2 Materials ……………………………………………………………39 3.1.3 Procedure ……………………………………………………………40 3.2 EEG recording parameters …………………………………………41 3.3 EEG data analysis procedure …………………………….....42 3.4 Results ……………………………………………………………………43 3.4.1 Behavioral data of sense effect ……………………………43 3.4.2 Behavioral data of lexicality effect ……………………44 3.4.3 Event-related potentials ………………………………….…45 N170 (150- 180 ms) …………………………………………………46 Frontal P200 (220-260 ms) …………………………………….……47 N400 …………………………………………………………………48 3.5 Discussion ……………………………………………………………51 4. EXPERIMENT 2 ……………………………………………………………57 4.1 Experiment 2 …………………………………………………………58 4.1.1 Participants ………………………………………………………58 4.1.2 Materials …………………………………………………………58 4.1.3 Procedure ……………………………………………………………59 4.2 Results …………………………………………………………………60 4.2.1 Behavioral data ……………………………………………………60 4.2.2 ERP data ……………………………………………………………61 N170 (150-180 ms) ………………………………………………....62 Frontal P200 (220-260 ms) …………………………………………63 N400 (350-500 ms) …………………………………………………63 4.3 Discussion …………………………………………………………………….65 Nouns and verbs ………………………………………………………67 4.4 Re-analyses …………………………………………………………69 4.4.1 Behavioral data ……………………………………………………69 4.4.2 ERP data ……………………………………………………………....71 Nouns …………………………………………………………………71 Verbs …………………………………………………………………74 4.5 Discussion 2 ………………………………………………………77 5. GENERAL DISCUSSION AND CONCLUSIONS ………………………81 5.1 Separate entries or single entry? …………………………81 5.2 Hemispheric processing of polysemy in different depth of tasks ………....82 5.3 Nouns and verbs ………………………………………………………84 5.4 Conclusions …………………………………………………………….85 References ……………………………………………….……………………86 Appendixes ………………………………………………………….…….94 / The current study used the manipulation of visual field and the number of senses of the first character in Chinese disyllabic compounds to investigate the representation of senses and the hemispheric processing of semantic polysemy. The ERP results in experiment 1 revealed crossover patterns in the LH and RH, which resembled the MEG data in Pylkkänen et al.’s study (2006). The sense facilitation in the LH was in favor of the assumption of single entry representation for senses. However, the inhibition in the RH yielded two possible interpretations: (1) the nature of hemispheric processing in dealing with semantic ambiguity; (2) the semantic activation from the separate-entry representation for senses. To clarify these possibilities, the depth of the task was changed. Experiment 2 was designed to push subjects to a deeper level of lexical processing through the word class judgment task. The results revealed the sense facilitation effect in the RH and suggested that in a deeper level, the RH had more possibility to observe the sense facilitation due to different efficiency of cerebral hemispheres in dealing with ambiguity. By chance, planned comparisons of the sense effect in different word classes suggested different distributions of the sense effects for nouns and verbs. For nouns, the sense effects were located in central-to-parietal areas while for verbs, the sense effects mainly were from the frontal area. In sum, the current study was in support of the account of single entry representation for senses, which was consistent with previous findings proposed by Beretta et al. (2005), Pylkkänen et al. (2006), and Rodd et al. (2002). Second, the research demonstrated that cerebral hemispheres played a role in semantic activation in a complementary way in which the LH was engaged in fine and focused semantic coding while the RH was more sophisticated in coarse coding and maintaining alternate meanings (e. g. Beeman & Chiarello, 1998; Burgess and Simpson, 1988). When the depth of tasks was changed, the RH advantage for the processing of semantically related senses was observed. Third, different distributions of the sense effects for nouns and verbs implied the distinct representations for different parts of speech in the brain.

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

Les épilepsies bénignes partielles idiopathiques de l'enfant sont associées à un pronostic favorable, car les crises sont rares et disparaissent à l'adolescence. La nature bénigne de ces syndromes est remise en question en raison de difficultés d'apprentissage et de déficits cognitifs subtils, fréquemment rapportés dans cette population. Nous étudions l’incidence des décharges épileptiques inter-critiques sur la cognition, et observons leurs influences sur l’organisation cérébrale et les fonctions cognitives. Nous proposons des épreuves informatisées, à des patients avec des pointes centro-temporales (EPCT) principalement localisées à l'un des deux hémisphères et occipitales de type Panayiotopoulos (SP), afin d'évaluer des compétences verbales, visuo-spatiales, visuo-attentionnelles, ainsi que trois processus d’imagerie mentale visuelle jamais étudiés dans ces syndromes. Les données comportementales renforcent l’idée d’une spécificité des perturbations selon la latéralisation hémisphérique des pointes inter-critiques et confirment leur incidence sur l’organisation de l’asymétrie hémisphérique fonctionnelle associée aux fonctions étudiées. Par ailleurs, nous montrons que le SP a une incidence particulièrement négative sur les processus d'imagerie mentale visuelle, compétences centrales pour la réussite scolaire de l’enfant et l’enrichissement de son imaginaire. Nos résultats sont en adéquation avec la remise en question actuelle de la nature bénigne de ces épilepsies sur le plan cognitif. Comparer les déficits et l’asymétrie hémisphérique fonctionnelle selon la localisation principale des pointes procure de nouveaux arguments pour un impact spécifique des manifestations inter-critiques, car seuls les mécanismes cognitifs sous-tendus par les régions concernées sont perturbés. Cela apporte des éléments d’explications sur les difficultés d'apprentissages signalés chez ces enfants, et incite à proposer des aménagements pédagogiques. / Benign idiopathic partial epilepsies of children are associated with a favorable prognosis because of rare seizure and usually recovery during adolescence. The benign nature of these syndromes is questioned because of learning difficulties and subtle cognitive deficits, frequently reported in this population. We study the incidence of the epileptic discharges on the cognition, and observe their influences on brain organization and cognitive functions. We propose computerized tests to patients with centrotemporal spikes (BECT) mainly localized in one of both hemispheres and occipital discharges, Panayiotopoulos syndrome (PS), to estimate verbal, visuo-spatial and visuo-attentional skills, as well as three visual imagery processes still never studied in these syndromes. Behavioural data strengthen the idea of a specific disturbances according to the hemispheric lateralization of the discharges and confirm their incidence on the organization of the functional hemispheric asymmetry associated with the studied functions. Furthermore, we show that PS has a particularly negative impact on the visual imagery process, important skills in the child's academic success and enrichment of his imagination. Our results are consistent with the current questioning of the benign nature of epilepsy on the cognitive level. Compare the deficits and the functional hemispheric asymmetry according to the main localization of discharges gets new arguments for a specific impact of the epileptiform activity, because only the cognitive mechanisms underlain by the concerned regions are disrupted. This provides evidence to explain the learning difficulties identified in these children, and encourages them to provide educational facilities.

Cette thèse concerne l’anatomie macroscopique des gyri de Heschl (GH) en relation avec la Préférence Manuelle (PM) et la Spécialisation Hémisphérique (SH) pour le langage étudiée dans une base de données multimodale dédiée à l’étude de la SH (la BIL&GIN), équilibrée pour le sexe et la PM. Le GH, situé à la surface du lobe temporal, abrite l’aire auditive primaire. Des études ont montré que le volume du GH est asymétrique gauche, et que le GH gauche (GHG) covarie avec les performances phonologiques et avec la quantité de cortex dévolu au traitement temporel des sons, suggérant une relation entre GHG et SH pour le langage. Pourtant l’anatomie des GH, très variable en terme de gyrification, est mal connue. Nous avons : 1- Décrit la distribution inter-hémisphérique de la gyrification des GH sur les images IRM anatomiques de 430 sujets. 2- Etudié les variations de surface et d’asymétrie du premier gyrus ou GH antérieur (GHa), montré sa diminution en présence de duplication et l’existence d’une asymétrie gauche pour les configurations les plus fréquentes avec GHG unique. Les gauchers présentaient moins de duplications droites et une perte de l’asymétrie gauche de GHa. 3- Testé si la variance de l’anatomie du GH expliquait la variabilité interindividuelle des asymétries mesurées en IRM fonctionnel pendant une tâche d’écoute de mots chez 281 sujets, et si les différences anatomiques liées à la PM étaient en relation avec une diminution de la SH pour le langage des gauchers. La distribution du nombre de GH expliquait 11% de la variance de l’asymétrie fonctionnelle du GH, les configurations à GHG unique étant les plus asymétriques gauches, sans effet de la PM sur la latéralisation fonctionnelle du GH. / This thesis concerns the macroscopical anatomy of Heschl’s gyri (HG) in relation with Manual Preference (MP) and the Hemispheric Specialization (HS) for language studied in a multimodal database dedicated to the investigation of HS and balanced for sex and MP (BIL&GIN). HG, located on the surface of the temporal lobe, hosts the primary auditory cortex. Previous studies have shown that HG volume is leftward asymmetrical and that the left HG (LHG) covaries with phonological performance and with the amount of cortex dedicated to the processing of the temporal aspects of sounds, suggesting a relationship between LHG and HSL. However HG anatomy is highly variable and little known. In this thesis we have: 1- Described HG inter-hemispheric gyrification pattern on the anatomical MRI images of 430 healthy participants. 2- Studied the variation of the first or anterior HG (aHG) surface area and its asymmetry and shown its reduction in the presence of duplication and that its leftward asymmetry was present only in the case of a single LHG. Left-handers exhibited a lower incidence of right duplication and a loss of aHG leftward asymmetry. 3- Tested whether the variance of HG anatomy explained the interindividual variability of asymmetries measured with fMRI during the listening of a list of words in 281 participants, and whether differences in HG anatomy with MP were related to decreased HS for language in left-handers. HG inter-hemispheric gyrification pattern explained 11% of the variance of HG functional asymmetry, the patterns including a unique LHG being those with the strongest leftward asymmetry. There was no incidence of MP on HG functional lateralization.

<p>This dissertation explains why behavioral genetic research can be better informed by using characteristics in the human iris as biomarkers for personality, and is divided into five parts. Part I gives an introduction to the classical twin method and an overview of the findings that have led most developmental researchers to recognize that the normal variation of personality depends on a complex interplay between genetic and environmental factors. Part II highlights empirical findings that during the last twenty years have gradually moved genetic and environmental theory and research to evolve toward one another, and also presents the theory of genetics and experience that currently is used to explain how the interplay between genes and the environment works. Part III explains why, from a developmental perspective, it is of interest to identify candidate genes for personality, and gives a brief overview of genes that have been associated with personality. Problems associated with genetic research on the molecular level and how these apply to personality are also highlighted. Part IV examines molecular research on the iris and the brain, which suggests that genes expressed in the iris could be associated with personality, and explains how the use of iris characteristics can increase power to test candidate genes for personality by taking advantage of the self-organizing properties of the nervous system. The empirical foundation for the questions posed in this dissertation and also the empirical results are presented here. Part V discusses the associations found between iris characteristics and personality, and exemplifies how iris characteristics can be used within the theoretical frameworks presented in parts I, II, III and IV. In other words, Part V explains how iris characteristics – in addition to identify as well as test candidate genes for personality – can be used to investigate how people’s experiences in themselves are influenced by genetic factors.</p>

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