Functional MRI of Language Processing and Recovery

__Abstract__ My thesis describe the utility of implementing fMRI to investigate how the language system is reorganized in brain damaged patients. Specifically for aphasia research fMRI allows to show how specific language treatment methods have the potential to enhance language reorganization and therefore optimize language recovery. Chapter 2 provides a brief introduction into the basics of language fMRI and task design for current applications of this technique in both clinical and research practice. I also summarized how different language levels have been explored with a variety of language tasks that have improved the neuroanatomical models of language processing. Chapter 3 explores the cerebro-cerebellar language lateralization pattern in healthy participants and in brain tumors patients with a focus on atypical language representation. Chapter 4 studies the differential auditory processing of spoken and melodically intoned language underlying MIT therapy. Chapter 5 focuses on the neural substrate of phonological and semantic auditory, i.e. receptive, processing in healthy older adults, group who is more applicable to aphasia research. I specifically focused on the functional specialization within the left inferior frontal gyrus (IFG), given its proposed important role for the recovery of language functions in aphasia. Chapter 6 explores the relationship between language lateralization and language recovery, both at the level of language production and comprehension, in 36 patients with mild and severe chronic aphasia after left hemispheric stroke. Chapter 7 investigates whether intensive MIT induces a shift in language lateralization in sub-acute and chronic non-fluent aphasic patients

Insight into the neurophysiological processes of melodically intoned language with functional MRI

Background: Melodic Intonation Therapy (MIT) uses the melodic elements of speech to improve language production in severe nonfluent aphasia. A crucial element of MIT is the melodically intoned auditory input: the patient listens to the therapist singing a target utterance. Such input of melodically intoned language facilitates production, whereas auditory input of spoken language does not. Methods: Using a sparse sampling fMRI sequence, we examined the differential auditory processing of spoken and melodically intoned language. Nineteen right-handed healthy volunteers performed an auditory lexical decision task in an event related design consisting of spoken and melodically intoned meaningful and meaningless items. The control conditions consisted of neutral utterances, either melodically intoned or spoken. Results: Irrespective of whether the items were normally spoken or melodically intoned, meaningful items showed greater activation in the supramarginal gyrus and inferior parietal lobule, predominantly in the left hemisphere. Melodically intoned language activated both temporal lobes rather symmetrically, as well as the right frontal lobe cortices, indicating that these regions are engaged in the acoustic complexity of melodically intoned stimuli. Compared to spoken language, melodically intoned language activated sensory motor regions and articulatory language networks in the left hemisphere, but only when meaningful language was used. Discussion: Our results suggest that the facilitatory effect of MIT may - in part - depend on an auditory input which combines melody and meaning. Conclusion: Combined melody and meaning provide a sound basis for the further investigation of melodic language processing in aphasic patients, and eventually the neurophysiological processes underlying MIT. Compared to spoken language, melodically intoned language activated sensory motor regions and articulatory language networks in the left hemisphere, but only when meaningful language was used. Our results suggest that the facilitatory effect of MIT may - in part - depend on an auditory input which combines melody and meaning. As such, they provide a sound basis for further investigation of melodic language processing in aphasic patients, and eventually the neurophysiological processes underlying MIT

Standardized evaluation of algorithms for computer-aided diagnosis of dementia based on structural MRI: The CADDementia challenge

Algorithms for computer-aided diagnosis of dementia based on structural MRI have demonstrated high performance in the literature, but are difficult to compare as different data sets and methodology were used for evaluation. In addition, it is unclear how the algorithms would perform on previously unseen data, and thus, how they would perform in clinical practice when there is no real opportunity to adapt the algorithm to the data at hand. To address these comparability, generalizability and clinical applicability issues, we organized a grand challenge that aimed to objectively compare algorithms based on a clinically representative multi-center data set. Using clinical practice as the starting point, the goal was to reproduce the clinical diagnosis. Therefore, we evaluated algorithms for multi-class classification of three diagnostic groups: patients with probable Alzheimer's disease, patients with mild cognitive impairment and healthy controls. The diagnosis based on clinical criteria was used as reference standard, as it was the best available reference despite its known limitations. For evaluation, a previously unseen test set was used consisting of 354 T1-weighted MRI scans with the diagnoses blinded. Fifteen research teams participated with a total of 29 algorithms. The algorithms were trained on a small training set (n = 30) and optionally on data from other sources (e.g., the Alzheimer's Disease Neuroimaging Initiative, the Australian Imaging Biomarkers and Lifestyle flagship study of aging). The best performing algorithm yielded an accuracy of 63.0% and an area under the receiver-operating-characteristic curve (AUC) of 78.8%. In general, the best performances were achieved using feature extraction based on voxel-based morphometry or a combination of features that included volume, cortical thickness, shape and intensity. The challenge is open for new submissions via the web-based framework: http://caddementia.grand-challenge.org

Imageability ratings across languages

Imageability is a psycholinguistic variable that indicates how well a word gives rise to a mental image or sensory experience. Imageability ratings are used extensively in psycholinguistic, neuropsychological, and aphasiological studies. However, little formal knowledge exists about whether and how these ratings are associated between and within languages. Fifteen imageability databases were cross-correlated using nonparametric statistics. Some of these corresponded to unpublished data collected within a European research network-the Collaboration of Aphasia Trialists (COST IS1208). All but four of the correlations were significant. The average strength of the correlations (rho = .68) and the variance explained (R (2) = 46%) were moderate. This implies that factors other than imageability may explain 54% of the results. Imageability ratings often correlate across languages. Different possibly interacting factors may explain the moderate strength and variance explained in the correlations: (1) linguistic and cultural factors; (2) intrinsic differences between the databases; (3) range effects; (4) small numbers of words in each database, equivalent words, and participants; and (5) mean age of the participants. The results suggest that imageability ratings may be used cross-linguistically. However, further understanding of the factors explaining the variance in the correlations will be needed before research and practical recommendations can be made

Intraregional Migration in Latin America: Psychological perspectives on acculturation and intergroup relations.

This book addresses the psychosocial causes, consequences, and underpinnings of intraregional migration in Latin America. War, political instability, and disparities in wealth and opportunity have long driven migration within Latin America, and this process shows no sign of slowing. In this book, cross-cultural and social psychologists address the urgent issues that face migrants throughout Central and South America. This includes overt prejudice and discrimination, particularly toward immigrants of indigenous or African-American origin; microaggressions; the tendency to positively value fair skin and European surnames; as well as political questions regarding the nature of citizenship and nationhood and links between legacies of colonialism and slavery and present-day inequality. Contributors offer conceptual, theoretical, and methodological tools for understanding the psychological processes that underlie migration and intergroup contact. Chapters focus on migration between and within countries in Central and South America, including Chile, Argentina, Bolivia, Costa Rica, Mexico, Peru, and Brazil.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Instituto de Investigaciones Psicológicas (IIP

Políticas públicas

Amputación de extremidades superiores: caracterización epidemiológicaAnálisis comparado de las políticas de promoción de la salud entre Chile y CataluñaAnálisis de los Avisa para la toma de decisiones en políticas de saludAntecedentes de colelitiasis en pacientes que presentaron colecistitis aguda. ¿Se puede prevenir la urgencia?Asociación entre alcoholemia y traumatismos en Copiapó, 2009Automedicación en la población asistente al Cesfam de Puerto NatalesAutotoma vaginal para detección de VPH para la prevención de cáncer cervicouterino, ChileCalidad de atención programa Auge- cáncer cervicouterino: la perspectiva de los profesionalesCaracterización de los casos de traumatismo encéfalo craneano en la comuna de Til-TilConocimiento de conductores universitarios sobre la alcoholemia permitida para conducir y su equivalencia en bebidas alcohólicasDescripción de la consulta dermatológica pediátrica en el Hospital Roberto del Río (2007-2008)Elementos para un abordaje metodológico de la salud intercultural en la Región Metropolitana de SantiagoEstudio descriptivo de consultas Sapu Cesfam Angachilla, visión tras dos años de registro clínico-electrónicoEstudio descriptivo de ingresos a Conin Valdivia, una revisión de 10 años (1998-2008)Estudio descriptivo de pacientes hospitalizados por absceso y celulitis peritonsilar en el hospital de PurranqueEvaluación de la aceptabilidad y consumo de alimentos del Pacam inscritos en el Cesfam Dr. V.M.FEvaluación de la interacción de medicinas alternativas o complementarias (MAC) en dos centros APSExposición a humo de tabaco ambiental. Signos y síntomas respiratorios bajos: estudio de prevalenciaFactores relacionados con la rotación laboral de médicos en consultorios del Gran SantiagoFibrosis quística como patología GES: una mirada críticaHipersensibilidad dentinaria: comparación de diferentes alternativas terapéuticasImpacto del GES en cáncer mamario: seguimiento a 5 años en un hospital del SSMSImplementación de la política nacional de medicamentos: percepción del profesional químico farmacéuticoLa implementación de políticas públicas cambió mortalidad de los pacientes gran quemado en Chile¿La infertilidad debería ser considerada un problema de salud pública en el Perú?Modelo de monitoreo de una política de protección a la infanciaMortalidad materna en el Hospital Dr. Alfredo van Grieken Coro, Estado Falcón, Venezuela 2005-2009Objetivos de desarrollo del milenio. Modelación de la mortalidad infantil Nicaragua - Costa Rica 1978-2008Percepción de riesgo y beneficio respecto del cigarrillo y su relación con el tabaquismo adolescentePolíticas públicas y salud intercultural: la experiencia de la organización indígena Taiñ adkimnPrevalencia de atipias celulares del cuello uterino en mujeres entre 18 y 24 añosProceso de ser histerectomizada: relatos de experiencias de mujeres en un hospital público de SantiagoProceso de ser histerectomizada: relatos de experiencias de mujeres en un hospital público de SantiagoPrograma Auge y cáncer cervicouterino: calidad de atención percibida por las usuarias del programaResolución quirúrgica por patología adenoamigdalina: ¿Es la población mapuche un grupo de riesgo?Resultados de alcoholemias tanatológicas del Servicio Médico Legal de Copiapó 1999-2009Resultados de la evaluación de los objetivos sanitarios de la década 2000-2010Una mirada a los servicios de salud para adolescentes en Puente Alt