Brain structural predispositions for music and language processing

[eng] It has been shown that music and language training can elicit plastic changes on brain structure and function bringing along behavioural benefits. For instance, musicians have been reported to have better auditory discrimination including pitch and speech-in-noise perception, motor-synchronization, verbal memory and general IQ than individuals without formal musical background. Also, bilinguals have shown higher executive function and attention-related abilities than monolinguals. Furthermore, altered functional and structural connectivity can be tracked to brain areas related to the activities most frequently performed by both musicians (instrumentalists and singers) and linguistic experts (such as bilinguals or professional phoneticians). While research in the last decade has devoted important effort to the study of brain plasticity, only a few investigations have addressed the connection between the initial functional or structural properties of brain networks related to auditory-motor function and subsequent language or musical training. Indeed, brain structural markers such as grey matter volume/density or white-matter diffusivity measurements from diffusion tensor imaging (DTI) data, as well as functional measurements from task- related activity or resting-state data from magnetic resonance imaging (MRI) or electroenceplhalography (EEG) have been demonstrated to correlate with consecutive performance and learning in the auditory-motor domain. The main goal of the present dissertation was twofold: we aimed to further the existing knowledge regarding brain plasticity elicited during putative sensitive periods and after long-term music practice, and to explore the white-matter pathways that predict linguistic or musical skills at baseline . Our secondary goals were to confirm previous findings regarding the brain structures involved in music and language processing, as well as to provide evidence of the benefits of usingstructural measurements and correlational analyses between imaging and behavioural data to study inter-individual differences. Study I focused on the comparison between professional pianists and non- musicians observing a complex pattern of increases and decreases in grey matter volume. In comparison to non-musician individuals, pianists showed greater grey matter volume in areas related to motor skill and the automatization of learned movements, as well as reinforcement learning and emotional processing. On the other hand, regions associated to sensorimotor control, score reading and auditory and musical perception presented a reduction in grey matter volume. Study II explored the relationship between white-matter structural properties of the arcuate fasciculus (AF) and the performance of native German speakers in a foreign- language (Hindi) sentence and word imitation task. We found that a greater left lateralization of the AF volume predicted performance on the imitation task. This result was confirmed by using not only a manual deterministic approach but also an automatic atlas-based fibre-reconstruction method, which in addition pointed out to a specific region in the anterior half of the left AF as the most related to imitation ability. Study III aimed to investigate whether the white-matter structural connectivity of the pathways previously described as targets for plasticity mechanisms in professional musicians predicted musical abilities in non-musicians. We observed that the white- matter microstructural organization of the right hemisphere pathways involved in motor-control (corticospinal tract) and auditory-motor transformations (AF) correlated with the performance of non-musician individuals during the initial stages of rhythmic and melodic learning. The present work confirmed the involvement of several brain structures previously described to display plastic effects associated to music and language training in the first stages of audio-motor learning. Furthermore, they challenge previous views regarding music-induced plasticity by showing that expertise is not always or uniquely correlated with increases in brain tissue. This raises the question of the role of efficiency mechanisms derived from professional-like practice. Most importantly, the results from these three studies converge in showing that a prediction-feedback-feedforward loop for auditory-motor processing may be crucially involved in both musical and language learning and skills. We thus suggest that brain auditory-motor systems previously described as participating in native language processing (cortical areas of the dorsal route for language processing and the AF that connects them) may also be recruited during exposure to new linguistic or musical material, being refined after sustained music practice.[spa] Estudios previos muestran que la formación musical y lingüística provoca cambios plásticos en las estructuras y funciones cerebrales, acompañándose también de beneficios conductuales. Por ejemplo, se ha descrito que los músicos poseen mejores habilidades de discriminación auditiva (incluyendo la percepción tonal y la discriminación del habla en un ambiente ruidoso), una mayor capacidad de sincronización motora, así como mejor memoria verbal y coeficiente intelectual general en comparación con personas sin formación musical. Paralelamente, los bilingües muestran mejores funciones ejecutivas y habilidades relacionadas con la atención en comparación con individuos monolingües. Además, las alteraciones en la conectividad cerebral funcional y estructural pueden ser rastreadas estudiando las áreas cerebrales relacionadas con las actividades más utilizadas por músicos (instrumentistas y cantantes) y expertos lingüísticos (como bilingües o fonetistas profesionales). Pese a que en la última década se han dedicado esfuerzos importantes en el campo de la investigación sobre la plasticidad cerebral, sólo unos pocos estudios han tratado de investigar la conexión entre las propiedades iniciales del cerebro, en cuanto a las funciones y estructuras que se relacionan con las funciones auditivo-motoras, y el posterior aprendizaje musical o del lenguaje. Sin embargo, los marcadores estructurales cerebrales, tales como volumen/densidad de materia gris o medidas de difusividad en la sustancia blanca a partir de datos de imagen del tensor de difusión, así como medidas funcionales de la actividad relacionada con una tarea o datos de resting-state (estado de reposo) obtenidos por resonancia magnética o electroencefalografía, han demostrado que pueden correlacionar con el rendimiento y el aprendizaje en el dominio auditivo- motor. En la presente tesis pretendíamos ampliar nuestro conocimiento en cuanto a la plasticidad cerebral obtenida durante los supuestos “períodos sensibles” y después de la práctica musical mantenida en el tiempo, por un lado, y explorar las vías de sustancia blanca que pueden predecir habilidades lingüísticas o musicales al inicio del aprendizaje, por otro lado. Como objetivos secundarios, queríamos confirmar resultados previos con respecto a las estructuras cerebrales involucradas en el procesamiento de la música y el lenguaje, así como apoyar el uso de mediciones estructurales y enfoques correlacionales (entre datos de neuroimagen y conductuales) para estudiar las diferencias inter- individuales. El Estudio I se centró en la comparación entre pianistas profesionales y no músicos, observando un complejo patrón de aumentos y disminuciones en el volumen de materia gris. En comparación con los individuos no músicos, los pianistas mostraron mayor volumen de sustancia gris en áreas relacionadas con la habilidad motora y la automatización de movimientos aprendidos, así como el aprendizaje a través del refuerzo y el procesamiento emocional, mientras que las regiones asociadas al control sensoriomotor, lectura de partituras y percepción auditiva y musical presentaron una reducción del volumen de materia gris. El Estudio II exploró la relación entre las propiedades estructurales de la materia blanca del fascículo arqueado (AF por sus siglas en inglés) y el rendimiento de hablantes nativos de alemán en una tarea de imitación de frases y palabras en una lengua extranjera (hindi). Encontramos que una mayor lateralización del volumen de AF hacia la izquierda predecía el desempeño en la tarea de imitación. Este resultado se confirmó utilizando no sólo un enfoque determinístico-manual sino también una reconstrucción automática (basada en atlas anatómicos) de las fibras de sustancia blanca que, además, señalaba una región específica en la mitad anterior del AF izquierdo como la más relacionada con las capacidades de imitación. El Estudio III tenía como objetivo investigar si la conectividad estructural de vías de sustancia blanca anteriormente descritas como dianas para los mecanismos de plasticidad en músicos profesionales, podría predecir las habilidades musicales en los no músicos. Se observó que la organización micro-estructural de la materia blanca en el hemisferio derecho en vías involucradas en el control motor (tracto corticoespinal) y en transformaciones auditivo-motoras (AF) correlacionaba con el desempeño de individuos no músicos en las etapas iniciales del aprendizaje rítmico y melódico. El presente trabajo ha confirmado la implicación en las primeras etapas del aprendizaje audio-motor de varias estructuras cerebrales que previamente habían mostrado efectos plásticos asociados al aprendizaje musical y del lenguaje. Además, estos resultados desafían las opiniones anteriores sobre la plasticidad inducida por la experiencia musical al demostrar que la experiencia no se correlaciona siempre ni únicamente con un aumento del tejido cerebral, y planteando así preguntas sobre los mecanismos de eficiencia derivados de la práctica musical a nivel profesional. Más importante aún es que los resultados de estos tres estudios convergen mostrando que un bucle de predicción–retroalimentación (feedback)–alimentación directa (feedforward) para el procesamiento auditivo-motor puede estar implicado de manera crucial tanto en el aprendizaje musical como en el aprendizaje de idiomas. Por tanto, sugerimos que los sistemas auditivo-motrices del cerebro, que previamente se habían descrito como participantes en el procesamiento del lenguaje nativo (áreas corticales involucradas en la vía dorsal para el procesamiento del lenguaje, y el AF, que las conecta) también pueden ser reclutados durante la exposición a material lingüístico o musical nuevo, siendo refinado tras años de práctica musical activ

Semantic radical consistency and character transparency effects in Chinese: an ERP study

BACKGROUND: This event-related potential (ERP) study aims to investigate the representation and temporal dynamics of Chinese orthography-to-semantics mappings by simultaneously manipulating character transparency and semantic radical consistency. Character components, referred to as radicals, make up the building blocks used dur...postprin

Neural correlates of phonological processing in Polish-English bilinguals: An fMRI study

Wydział AnglistykiNiniejsza dysertacja bada problem neuronalnych korelatów przetwarzania fonologicznego języka ojczystego i języka obcego u polskich użytkowników języka angielskiego. W celu wskazania struktur i funkcji mózgu odpowiedzialnych za przetwarzanie fonologiczne stworzono zestaw eksperymentów, które przeprowadzono na grupie średniozaawansowanych polskich użytkowników języka angielskiego. Korzystając z metody rezonansu magnetycznego sprawdzono hipotezę zakładającą zrózżnicowanie w reprezentacji procesów fonologicznych w mózgu, w zależności od przetwarzanego języka oraz stopnia zaawansowania użytkownika. Zestaw zawierał cztery eksperymenty z zadaniami w języku polskim i angielskim, takimi jak słuchanie pasywne, Test Pamięci Roboczej Sternberga, test fluencji słownej, oraz Test Leksykalny dla Zaawansowanych Uczniów Języka Angielskiego. Na eksperymenty złożyły się również trzy eksperymenty nie oparte na żadnych zadaniach. Wyniki wraz z dokładną dyskusją sugerują model przetwarzania drugiego języka, który składa się z modułów związanych z zadaniami językowymi zbudowanych ze współgrających ze sobą sieci mózgowych. W związku z tym, niniejsza dysertacja wnosi nowe odkrycia do dziedzin językoznawstwa i neuronauki, poszerzając nasze zrozumienie procesów przetwarzania języka w mózgu.The present thesis investigates the issue of neural basis for phonological processing of native and non-native speech in Polish-English bilinguals. In order to pinpoint the structures and functions that are relevant to phonological processing, a set of experiments was devised on a group of moderately proficient Polish-English bilinguals. Using the method of Magnetic Resonance Imaging, and hypothesizing that there will be differences in the representation of phonological processes in the brain, dependent on the language and the level of proficiency in the language, four task-based experiments in both Polish and English, including listening to stories, Sternberg Working Memory Task, Verbal Fluency Task, and Lexical Test for Advanced Learners of English, and three task-independent experiments were conducted. The results of the thesis, along with the detailed discussion suggest a model of phonological processing in L2, which consists of different task-related modules of interacting brain networks. As such, the present thesis contributes to both fields of linguistics and neuroscience, broadening the understanding of how the brain processes language

Brain anatomical correlates of perceptual phonological proficiency and language learning aptitude

The present dissertation concerns how brain tissue properties reflect proficiency in two aspects of language use: the ability to use tonal cues on word stems to predict how words will end and the aptitude for learning foreign languages. While it is known that people differ in their language abilities and that damage to brain tissue cause loss of cognitive functions, it is largely unknown if differences in language proficiencies correlate with differences in brain structure. The first two studies examine correlations between cortical morphometry, i.e. the thickness and surface area of the cortex, and the degree of dependency on word accents for processing upcoming suffixes in Swedish native speakers. Word accents in Swedish facilitate speech processing by having predictive associations to specific suffixes, (e.g. fläckaccent1+en ‘spot+singular’, fläckaccent2+ar ‘spot+plural’). This use of word accents, as phonological cues to inflectional suffixes, is relatively unique among the world’s languages. How much a speaker depends on word accents in speech processing can be measured as the difference in response time (RT) between valid and invalid word accent-suffix combinations when asked to identify the inflected form of a word. This can be thought of as a measure of perceptual phonological proficiency in native speakers. Perceptual phonological proficiency is otherwise very difficult to study, as most phonological contrasts are mandatory to properly interpret the meaning of utterances. Study I compares the cortical morphometrical correlates in the planum temporale and inferior frontal gyrus pars opercularis in relation to RT differences in tasks involving real words and pseudowords. We found that thickness of the left planum temporale correlates with perceptual phonological proficiency in lexical words but not pseudowords. This could implicate that word accents are part of full-form representations of familiar words. Moreover, for pseudowords but not lexical words, the thickness of the inferior frontal gyrus pars opercularis correlates with perceptual phonological proficiency. This association could reflect a greater importance for decompositional analysis in which word accents are part of a set of rules listeners need to rely on during processing of novel words. In study II, the investigation of the association between perceptual phonological proficiency in real words with cortical morphometry is expanded to the entire brain. Results show that cortical thickness and surface area of anterior temporal lobe areas, known constituents of a ventral sound-to-meaning language-processing stream is associated with greater perceptual phonological proficiency. This is consistent with a role for word accents in aiding putting together the meaning of or accessing a whole word representation of an inflected word form. Studies III and IV investigate the cortical morphometric associations with language learning aptitude. Findings in study III suggest that aptitude for grammatical inferencing, i.e. the ability to analytically discern the rules of a language, is associated with cortical thickness in the left inferior frontal gyrus pars triangularis. Furthermore, pitch discrimination proficiency, a skill related to language learning ability, correlates negatively with cortical thickness in the right homologue area. Moreover, study IV, using improved imaging techniques, reports on a correlation between vocabulary learning aptitude and cortical surface area in the left inferior precuneus as well as a negative correlation between diffusional axial kurtosis and phonetic memory in the left arcuate fasciculus and subsegment III of the superior longitudinal fasciculus. However, the finding correlation between cortical thickness and grammatical inferencing skill from study III was not replicated in study IV.Taken together, the present dissertation shows that differences in some language proficiencies are associated with regionally thicker or larger cortex and more coherent white matter tracts, the nature and spatial locus of which depend on the proficiency studied. The studies add to our understanding of how language proficiencies are represented in the brain’s anatomy

Investigating the motor-sensory learning of foreign speech

This thesis presents an investigation of bilingualism as a motor learning skill, with success ultimately measured in terms of strength of a foreign accent, in contrast to the many studies of bilingualism in terms of linguistic competence. My research used functional magnetic resonance (fMRI) imaging to investigate feedforward (motor) and feedback (auditory and somatosensory) systems involved in the production of foreign speech and how these systems are modulated by proficiency levels. I investigated the function of the frontal operculum and the temporo-parietal junction (TPJ) – planum temporale (posterior auditory association cortex) and parietal operculum (somatosensory association cortex) – during speech. The frontal operculum, strongly lateralised to the left, has been associated with speech since Broca performed his classic post mortem lesion-deficit analysis. Interest in the TPJ has arisen because of recent publications proposing the posterior half of the left planum temporale (± adjacent parietal operculum) as a ‘sensorimotor interface’ for speech production. My research compared activity within the frontal operculum and the TPJ during overt and covert speech. A second fMRI study examined retrospective proficiency based on existing language skills in people with English as a foreign language who were scanned during speech production in their native language and in English. A third fMRI study manipulated proficiency by training monolingual native English participants in the production of foreign speech sounds, with scanning pre- and post-training. This allowed measures of changes in activity (indicating rapid plasticity) following a short period of behavioural training in articulating novel foreign speech sounds. Training effects were observed predominantly in the striatum, and further analyses indicated that striatal activity in vocal learning is modulated by proficiency

Neuronal Correlates of Diacritics and an Optimization Algorithm for Brain Mapping and Detecting Brain Function by way of Functional Magnetic Resonance Imaging

The purpose of this thesis is threefold: 1) A behavioral examination of the role of diacritics in Arabic, 2) A functional magnetic resonance imaging (fMRI) investigative study of diacritics in Arabic, and 3) An optimization algorithm for brain mapping and detecting brain function. Firstly, the role of diacritics in Arabic was examined behaviorally. The stimulus was a lexical decision task (LDT) that constituted of low, mid, and high frequency words and nonwords; with and without diacritics. Results showed that the presence of vowel diacritics slowed reaction time but did not affect word recognition accuracy. The longer reaction times for words with diacritics versus without diacritics suggest that the diacritics may contribute to differences in word recognition strategies. Secondly, an Event-related fMRI experiment of lexical decisions associated with real words with versus without diacritics in Arabic readers was done. Real words with no diacritics yielded shorter response times and stronger activation than with real words with diacritics in the hippocampus and middle temporal gyrus possibly reflecting a search from among multiple meanings associated with these words in a semantic store. In contrast, real words with diacritics had longer response times than real words without diacritics and activated the insula and frontal areas suggestive of phonological and semantic mediation in lexical retrieval. Both the behavioral and fMRI results in this study appear to support a role for diacritics in reading in Arabic. The third research work in this thesis is an optimization algorithm for fMRI data analysis. Current data-driven approaches for fMRI data analysis, such as independent component analysis (ICA), rely on algorithms that may have low computational expense, but are much more prone to suboptimal results. In this work, a genetic algorithm (GA) based on a clustering technique was designed, developed, and implemented for fMRI ICA data analysis. Results for the algorithm, GAICA, showed that although it might be computationally expensive; it provides global optimum convergence and results. Therefore, GAICA can be used as a complimentary or supplementary technique for brain mapping and detecting brain function by way of fMRI

Les corrélats comportementaux et neurofonctionnels de la thérapie par analyse des composantes phonologiques

L'aphasie est un trouble acquis du langage qui cause des difficultés de communication pouvant affecter la compréhension et l'expression. Lorsque l'aphasie survient par suite d’un accident vasculaire cérébral, des difficultés importantes de communication sont initialement constatées, puis une amélioration graduelle dans les semaines et les mois qui suivent. Toutefois, pour certaines personnes, l’aphasie peut rester sévère un an, l’aphasie est alors considérée comme chronique. L'une des manifestations les plus courantes de l'aphasie est l'anomie - un manque de mots. Un nombre croissant d'études se penchent sur l'impact de la thérapie sur l'aphasie chronique et ont montré une amélioration du langage après plusieurs années. Des thérapies sont développées et étudiées en anglais, mais peu d’écrits scientifiques décrivent les effets des thérapies spécifiques et formalisées en français. Le but du présent travail doctoral est d'examiner les effets comportementaux et d’explorer les substrats neurologies du protocole Analyse des Composantes Phonologiques (ACP) ainsi que l’influence des facteurs individuels sur les gains chez dix-huit personnes vivant avec une aphasie chronique. Ainsi, la thèse comporte trois articles qui abordent, chacun, des facettes différentes des effets de l’ACP. Dans le premier article, les effets comportementaux de l’ACP sont explorés ainsi que le rôle des facteurs individuels sur la réponse à l’intervention. Le deuxième considère l’effet de l’ACP sur la connectivité fonctionnelle du cerveau, tout en considérant l’effet des facteurs individuels. Enfin, le troisième article s’intéresse à la réponse par suite de l’intervention ACP en considérant les facteurs individuels du bilinguisme et des caractéristiques neuroanatomiques comme la localisation des lésions et l’épaisseur corticale. L'ensemble de résultats démontre une amélioration significative de la dénomination des noms parmi les dix-huit participant·e·s inclus·e·s. Par ailleurs, cette amélioration a été mesurée sur des mots non-traités, ce qui reflète un effet de généralisation. Par surcroit, cette amélioration se maintient à trois mois et six mois après la fin de l’intervention. L’âge, la sévérité de l’anomie et la présence d’une apraxie de la parole sévère influencent les gains mesurés. Les analyses neurofonctionnelles de connectivité fonctionnelle au repos auprès de dix participant·e·s montrent une meilleure intégration des réseaux visuels et langagiers, associés lors d’une tâche de dénomination des noms. Les changements de connectivité observés dépendent de la sévérité de l'aphasie. Plus spécifiquement, l’intégration interhémisphérique et au sein de l’hémisphère droit est plus importante chez les personnes ayant une aphasie plus légère. Finalement, être bilingue influence aussi les gains observés par suite du protocole Analyse des Composantes Phonologiques. Les personnes bilingues s’améliorent davantage, cet avantage est associé une épaisseur corticale supérieure dans l’hémisphère droit comparativement aux personnes monolingues. Ces données préliminaires suggèrent que les changements comportementaux observés résultent de la combinaison des composantes phonologiques et orthographiques de l'intervention, et que l’intervention requiert et entraîne les fonctions exécutives. Les données cueillies dans le cadre de cette thèse sont prometteuses en ce qui concerne les effets bénéfiques de l’Analyse des Composantes Phonologiques en français. Plus précisément, les gains mesurés auprès d’un échantillon présentant des symptômes variés, la généralisation et le maintien supportent l’utilisation de ce protocole d’intervention auprès de personnes francophones. Il est à noter que la taille du groupe étudié est modeste, mais les méthodologies complémentaires et la convergence des résultats avec les données existantes dans les écrits scientifiques et à travers les méthodes d'étude de cette thèse (niveaux comportemental et neurofonctionnel) justifient des études subséquentes pour mieux comprendre les mécanismes d'action et l’influence des facteurs individuels sur les gains.Aphasia is an acquired language disorder that causes communication difficulties that can affect understanding and expression. When aphasia occurs following a stroke, significant communication difficulties are initially noted, followed by gradual improvement over the following weeks and months. However, for some people, the aphasia may remain severe after a year even when recovery has been seen, in which case the aphasia is considered chronic. One of the most common symptoms in aphasia is anomia - a difficulty finding and saying words. A growing number of studies are looking at the impact of speech and language therapy on chronic aphasia and have shown improvement in language after several years. Therapies are developed and studied in English, but little scientific literature describes the effects of specific, formalized therapies in French. The purpose of the present doctoral work is to examine the behavioural effects and to explore the neurological substrates of the Phonological Component Analysis (PCA) protocol as well as the influence of individual factors on gains in 18 adults living with chronic aphasia. Thus, the dissertation consists of three articles, each of which addresses different facets of the effects of PCA. In the first article, the behavioural effects of PCA are explored as well as the role of individual factors on the response to the intervention. The second considers the effect of PCA on resting-state functional brain connectivity, while considering the effect of individual factors. Finally, the third paper looks at the response to the PCA intervention by considering the individual factors of bilingualism and neuroanatomical characteristics associated such as cortical thickness, and also lesion location. The overall results show a significant improvement in naming among the eighteen participants included in the thesis. Moreover, this improvement was measured on untreated words, which reflects a generalization effect and was maintained at three and six months after the end of the intervention. Age, severity of impairment and the presence of severe apraxia of speech influenced the measured gains. Neurofunctional analyses of resting-state functional connectivity in ten participants showed improved integration of the visual and language networks, associated during a naming task. The connectivity changes observed depend on the severity of the aphasia. More specifically, interhemispheric and right hemisphere integration is greater in individuals with milder aphasia. Finally, being bilingual also influences the gains observed following the Phonological Component Analysis protocol. Bilinguals improved more, and this advantage was associated with greater cortical thickness in frontal regions of the right hemisphere compared to monolinguals. These preliminary data suggest that the observed behavioural changes result from the combination of the phonological and orthographic components of the intervention, and that the intervention requires and trains executive functions. The data collected in this thesis show promise for the beneficial effects of Phonological Component Analysis in French. Specifically, the gains, generalization, and maintenance measured in a sample of adults living with aphasia displaying varied symptoms support the use of this intervention protocol with French speakers. It should be noted that the size of the study group is modest, but the complementary methodologies and the convergence of the results with existing data in the scientific literature and through the study methods of this thesis (behavioural and neurofunctional levels) justify subsequent studies to better understand the mechanisms of action and the influence of individual factors on gains

Cross-Linguistic Transfer (CLT) in Bilingual Speakers : Neural Correlates of Language Learning

Le but de cette thèse est d'étudier les corrélats comportementaux et neuronaux du transfert inter-linguistique (TIL) dans l'apprentissage d’une langue seconde (L2). Compte tenu de nos connaissances sur l'influence de la distance linguistique sur le TIL (Paradis, 1987, 2004; Odlin, 1989, 2004, 2005; Gollan, 2005; Ringbom, 2007), nous avons examiné l'effet de facilitation de la similarité phonologique à l’aide de la résonance magnétique fonctionnelle entre des langues linguistiquement proches (espagnol-français) et des langues linguistiquement éloignées (persan-français). L'étude I rapporte les résultats obtenus pour des langues linguistiquement proches (espagnol-français), alors que l'étude II porte sur des langues linguistiquement éloignées (persan-français). Puis, les changements de connectivité fonctionnelle dans le réseau langagier (Price, 2010) et dans le réseau de contrôle supplémentaire impliqué dans le traitement d’une langue seconde (Abutalebi & Green, 2007) lors de l’apprentissage d’une langue linguistiquement éloignée (persan-français) sont rapportés dans l’étude III. Les résultats des analyses d’IRMF suivant le modèle linéaire général chez les bilingues de langues linguistiquement proches (français-espagnol) montrent que le traitement des mots phonologiquement similaires dans les deux langues (cognates et clangs) compte sur un réseau neuronal partagé par la langue maternelle (L1) et la L2, tandis que le traitement des mots phonologiquement éloignés (non-clang-non-cognates) active des structures impliquées dans le traitement de la mémoire de travail et d'attention. Toutefois, chez les personnes bilingues de L1-L2 linguistiquement éloignées (français-persan), même les mots phonologiquement similaires à travers les langues (cognates et clangs) activent des régions connues pour être impliquées dans l'attention et le contrôle cognitif. Par ailleurs, les mots phonologiquement éloignés (non-clang-non-cognates) activent des régions usuellement associées à la mémoire de travail et aux fonctions exécutives. Ainsi, le facteur de distance inter-linguistique entre L1 et L2 module la charge cognitive sur la base du degré de similarité phonologiques entres les items en L1 et L2. Des structures soutenant les processus impliqués dans le traitement exécutif sont recrutées afin de compenser pour des demandes cognitives. Lorsque la compétence linguistique en L2 augmente et que les tâches linguistiques exigent ainsi moins d’effort, la demande pour les ressources cognitives diminue. Tel que déjà rapporté (Majerus, et al, 2008; Prat, et al, 2007; Veroude, et al, 2010; Dodel, et al, 2005; Coynel, et al ., 2009), les résultats des analyses de connectivité fonctionnelle montrent qu’après l’entraînement la valeur d'intégration (connectivité fonctionnelle) diminue puisqu’il y a moins de circulation du flux d'information. Les résultats de cette recherche contribuent à une meilleure compréhension des aspects neurocognitifs et de plasticité cérébrale du TIL ainsi que l'impact de la distance linguistique dans l'apprentissage des langues. Ces résultats ont des implications dans les stratégies d'apprentissage d’une L2, les méthodes d’enseignement d’une L2 ainsi que le développement d'approches thérapeutiques chez des patients bilingues qui souffrent de troubles langagiers.The purpose of this thesis was to study the behavioral and neural correlates of Cross-linguistic Transfer effects (CLT) at the word level, in second language learning. Moreover, given that language distance has an impact on CLT, (Paradis, 1987, 2004, Odlin, 1989, 2004, 2005, Gollan, 2005, Ringbom, 2007), two distinct language pairs were examined: Close language pairs (Spanish-French) and distant language pairs (Persian-French). This thesis comprises three studies. In study I, Spanish speakers and in study II Persian speakers were trained for lexical learning until consolidation level. Cognates (phonologically and semantically similar words), Clangs (phonologically similar words with different meanings), and Non-cognate-non-clangs (semantically similar words), were presented in a picture naming task. Accuracy rates and response times as well as event-related fMRI BOLD responses to each word category were measured. Simple and direct contrasts with phonologically similar and phonologically distant words were performed. Thus, Study I reports the results of close languages (Spanish-French) and Study II, reports the results of distant languages (Persian-French). The neurocognitive processing of language learning was further investigated in terms of networks using functional connectivity analysis in distant languages (Persian-French) and the results are reported in Study III. The Results with the General Linear Model analysis show that with close language pairs (French-Spanish), the processing of phonologically similar words (cognates and clangs) relies upon a shared L1-L2 language specific neural areas, whereas processing of phonologically distant words (non-clang-non-cognates), activates L1 language processing areas, but also relies upon working memory, attentional, and processing structures. However, with distant language pairs (French-Persian), even phonologically similar words (cognates and clangs) activate areas known to be involved in attentional processing and cognitive control. Moreover, phonologically distant words (non-clang-non-cognates) also activate areas involved in working memory and executive function processing structures. Thus, the factor of L1-L2 cross-linguistic distance appears to modulate the executive load imposed to the system, on the basis of the degree of phonological overlap between L1-L2 items; thus in order to compensate for more effortful processing demands, the system recruits executive function supporting structures. The results of the connectivity analysis show that, in line with literature (Majerus, et al., 2008; Prat, et al., 2007; Veroude, et al., 2010; Dodel, et al., 2005; Coynel, et al., 2009), when the language proficiency is low, there is enhanced functional connectivity between and within language specific and other cognitive processing (working memory, attentional and cognitive control) networks. However, as proficiency increases, integration values (functional connectivity) decrease. This reflects that language tasks become less effortful and demand less cognitive resources. The results of this dissertation contribute to a better understanding of CLT effects on L2 learning, both in regards to different word types and L1-L2 language distance. These results have implications with regards to L2 learning and teaching strategies and approaches as well as with regards to the development of data-driven therapy approaches in the case of language break down in bilingual population

The neural processing of sentences in bilinguals and monolinguals: an fMRI study of portugues-english bilinguals and portuguese monolinguals reading comprehension effects on brain activation

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Inglês: Estudos Linguísticos e Literários, Florianópolis, 2016.Abstract : Although considerable research has been devoted to language representation and processing in monolinguals, rather less attention has been paid to language representation and processing in bilinguals and even less, to the comparison in brain activation between bilinguals and monolinguals reading in their L1. Since the majority of studies on bilingualism investigate processes at the word level, the present dissertation, a cross-sectional, quantitative and exploratory study in nature, aimed at investigating monolingual and bilingual brains and their neuroanatomical response to the processing of written sentences. More specifically, it sought to explore (1) whether and to what extent Portuguese and English are represented and processed in the same areas of the brain in late bilinguals; (2) whether Portuguese is represented and processed in same brain areas in bilinguals and monolinguals; (3) whether the semantic neural representation of sentences in one language can be identified based on the brain activation for the same sentences in another language; (4) whether individual differences, namely proficiency in the second language and working memory capacity, modulate activation in bilinguals, whether working memory capacity modulate activation in monolinguals; and (5), whether word length and lexical frequency have an effect on brain activation. Twelve Brazilian Portuguese-English late bilinguals and ten Brazilian Portuguese monolinguals participated in the study. Data collection took place at Carnegie Mellon University during a PhD internship. The stimuli consisted of 60 sentences in English and their translation-equivalent sentences in Portuguese (e.g., The diplomat negotiated at the embassy/O diplomata negociou na embaixada). Bilingual participants read the sentences while functional images were acquired on two separate days while monolinguals only read the Portuguese sentences in a single session. Data were analyzed statistically and revealed, in general terms, that language representation and processing engages a complex network of brain areas in monolinguals and bilinguals. For processing the L2, bilinguals recruit a more widely distributed set of areas bilaterally than for processing the L1 (more left-lateralized). For processing the L1, in comparison with monolinguals, bilinguals recruited additional bilateral areas for dealing with the phonological and semantic aspects of the L1. In spite of the small differences in processing the languages, the commonalities in concept representations across languages were sufficient to allow decoding of sentences using multi-voxel pattern analysis and machine learning techniques. The model generated reasonable accurate predictions of the neural representation of words in the context of sentences based on simple addition of words, semantic features and semantic cuboids derived from an independent study. Variables as proficiency in the L2, working memory capacity, word length and lexical frequency modulated brain activation. In a nutshell, findings add support to the literature about bilingual and monolingual language comprehension and contribute to the area by suggesting that there are common neural areas involved in the representation of different languages and cultures.Embora um considerável número de pesquisas tem se dedicado à representação e ao processamento da linguagem em monolíngues, menos atenção tem sido dada à representação e ao processamento da linguagem em bilíngues e ainda menos, à comparação da ativação cerebral de bilíngues e monolíngues ao ler sua L1. Já que a maioria dos estudos sobre bilinguismo investigam processos no nível da palavra, a presente tese, um estudo de natureza transversal, quantitativa e exploratória, objetivou investigar cérebros de monolíngues e bilíngues e sua resposta neuroanatômica ao processamento de frases escritas. Mais especificamente, procurou explorar (1) se as duas línguas, português e inglês, são representadas e processadas nas mesmas áreas do cérebro de bilíngues tardios e em que medida; (2) se a L1 (português) é representada e processada nas mesmas áreas cerebrais de bilíngues e monolíngues; (3) se a representação neural semântica de frases em uma língua pode ser identificada baseada na ativação cerebral das mesmas frases na outra língua; (4) se diferenças individuais como a proficiência na segunda língua e a capacidade de memória de trabalho modulam a ativação em bilíngues e se a capacidade de memória de trabalho modula a ativação em monolíngues; e (5) se a extensão das palavras e a frequência lexical têm efeito na ativação cerebral. Doze bilíngues tardios do par linguístico português brasileiro-inglês e 10 monolíngues do português brasileiro participaram do estudo. Os dados foram coletados na Carnegie Mellon University durante o doutorado sanduíche. Os estímulos consistiram de 60 frases em inglês e frases equivalentes em português (ex.: The diplomat negotiated at the embassy/O diplomata negociou na embaixada). Os participantes bilíngues leram as frases enquanto imagens funcionais do cérebro eram adquiridas em dois dias distintos enquanto os participantes monolíngues apenas leram as frases em português numa única sessão. Os dados foram analisados estatisticamente e revelam, em termos gerais, que a representação e o processamento da linguagem engaja uma rede complexa de áreas cerebrais em monolíngues e bilíngues. Para processar a L2, os bilíngues recrutam um conjunto mais amplamente distribuído de áreas bilaterais que para processar a L1 (mais lateralizada à esquerda). Para processar a L1, em comparação com os monolíngues, os bilíngues recrutaram áreas adicionais bilateralmente para lidar com os aspectos fonológicos e semânticos da L1. Apesar das pequenas diferenças no processamento das línguas, as semelhanças na representação dos conceitos entre as línguas foram suficientes para permitir a decodificação de frases usando técnicas de aprendizagem de máquina e de análise de padrão multi-voxel. O modelo gerou predições razoavelmente precisas da representação neural de palavras no contexto de frases baseado na adição simples de palavras, características semânticas e cuboides semânticos derivados de um estudo independente. Variáveis como a proficiência na L2, a capacidade de memória de trabalho, a extensão das palavras, e a frequência lexical influenciaram a ativação cerebral. Em suma, os achados corroboram a literatura sobre compreensão de linguagem em monolíngues e bilíngues e contribuem com a área ao sugerir que há áreas neurais comuns envolvidas na representação de diferentes línguas e culturas