ABSTRACT
INTRODUCTION: Learning disabilities constitute a heterogeneous group of disorders that involve significant alterations in different cognitive domains (acquisition and use of language, reasoning, mathematical skills, visuospatial abilities, and so forth) that are not accounted for by a low level of intelligence, inadequate sociocultural development or lack of academic opportunities. They result from an alteration in basic psychological processes, developmentally linked to an alteration in the central nervous system. Current functional neuroimaging techniques have made it possible to develop a new type of approach to the neurofunctional foundations underlying these disorders, especially with regard to difficulties in the realm of reading/ writing (developmental dyslexia) and attention deficit hyperactivity disorder (ADHD), which have their highest incidence among the infantile population of school-age children. DEVELOPMENT: Neuroimaging studies have revealed a pattern of atypical activity in both kinds of disorders. In the case of dyslexia, alterations have been observed in the perisylvian circuits that underlie the mechanisms involved in reading skills. Studies into ADHD suggest a fronto-striatal dysfunction linked to the difficulties encountered to achieve inhibitory control, as well as alterations in the inferior parietal and posterior temporal cortex. CONCLUSIONS: Functional neuroimaging studies have shown that the clinical manifestations of these disorders are not only due to a dysfunction in specific areas of the brain, but also to alterations in the pattern of connectivity.
Subject(s)
Learning Disabilities/diagnosis , Child , Humans , Magnetic Resonance Imaging , MagnetoencephalographyABSTRACT
Introducción. Las dificultades de aprendizaje comprendenun grupo heterogéneo de trastornos que implican alteracionessignificativas en diferentes dominios cognitivos (adquisición y usodel lenguaje, razonamiento, habilidades matemáticas, visuoespaciales,etc.) no justificadas por bajo nivel intelectual, desarrollosociocultural inadecuado o falta de oportunidades académicas.Éstas son el resultado de una alteración en los procesos psicológicosbásicos, evolutivamente ligados a una alteración del sistemanervioso central. Las actuales técnicas de neuroimagen funcionalhan permitido un nuevo tipo de acercamiento a las bases neurofuncionalesde estos trastornos, particularmente de las dificultades enel ámbito de la lectoescritura (dislexia evolutiva) y del trastornopor déficit de atención e hiperactividad (TDAH), los cuales tienenel mayor nivel de incidencia en la población escolar infantil. Desarrollo.Los estudios de neuroimagen han revelado un patrón de actividadatípico en ambos tipos de trastorno. En el caso de la dislexia,se han observado alteraciones de los circuitos perisilvianosque sustentan los mecanismos de lectura. Los estudios sobre TDAHsugieren una disfunción frontoestriatal ligada a las dificultadespara el control inhibitorio, así como alteraciones en la cortezatemporal posterior y parietal inferior. Conclusiones. Los estudiosde neuroimagen funcional revelan que las manifestaciones clínicasde estos trastornos no se deben sólo a la disfunción de áreas cerebralesconcretas, sino también a alteraciones en el patrón de conectividad
Introduction. Learning disabilities constitute a heterogeneous group of disorders that involve significant alterationsin different cognitive domains (acquisition and use of language, reasoning, mathematical skills, visuospatial abilities, and soforth) that are not accounted for by a low level of intelligence, inadequate sociocultural development or lack of academicopportunities. They result from an alteration in basic psychological processes, developmentally linked to an alteration in thecentral nervous system. Current functional neuroimaging techniques have made it possible to develop a new type of approachto the neurofunctional foundations underlying these disorders, especially with regard to difficulties in the realm of reading/writing (developmental dyslexia) and attention deficit hyperactivity disorder (ADHD), which have their highest incidenceamong the infantile population of school-age children. Development. Neuroimaging studies have revealed a pattern ofatypical activity in both kinds of disorders. In the case of dyslexia, alterations have been observed in the perisylvian circuitsthat underlie the mechanisms involved in reading skills. Studies into ADHD suggest a fronto-striatal dysfunction linked to thedifficulties encountered to achieve inhibitory control, as well as alterations in the inferior parietal and posterior temporalcortex. Conclusions. Functional neuroimaging studies have shown that the clinical manifestations of these disorders are notonly due to a dysfunction in specific areas of the brain, but also to alterations in the pattern of connectivity
