Dislexia La dislexia es un desrden con bases neurolgicas, frecuentemente familiar, que interfiere con la adquisicin del lenguaje. Vara en su grado de severidad, se manifiesta por dificultades en el lenguaje receptivo y expresivo, incluyendo el procesamiento fonolgico, lectura, escritura, ortografa y en ocasiones, la aritmtica. La dislexia no es el resultado de falta de motivacin, problemas sensoriales, oportunidades educacionales o ambientales inadecuadas, aunque puede ocurrir junto con esas condiciones. Aunque la dislexia es de por vida los individuos con frecuencia responden a una intervencin temprana y adecuada." (Orton Dyslexia Society, 1994).

Dislexia Trastorno MultifactorialF. Ramus, 2002

Dislexia

Activacin Neuronal de la LecturaNormalDislexia

Mapa del Cerebro Dislxico

Ciertas regiones cerebrales de personas con la forma mas comn de dislexia muestran una disminucin de su funcin cuando estn leyendo. (Proc Natl Acad Sci USA. 1998;95:2636-2641).

Las imgenes revelan una firma cerebral para el desrden de dislexia.

Las tcnicas de imgen revelan que reas diferentes del cerebro se activan (en rojo) en personas normales y con dislexia.

Anormalidades neuronales entre el grupo de dislexia y normal ante el procesamientoFonolgico de estmulos visuales. A pesar de las diferentes metodologas (PET [26,27,29] y fMRI [28,30**]) , tareas (letras en rima [26.28.30**], pseudopalabras [27,29,34**], tareas implcitas y explcitas [29,34**] tcnicas de anlisis (regin de inters) [28] yMapeo estadstico paramtrico [26,27,29,30**,34**], grupos de edad (nios [30**]) yAdultos [26,-29, 34**], y lenguajes [34**], todos los estudios mostraron actividaddisminuda en la parte posterior del hemisferio izquierdo en la zona de lenguaje, Corteza temporoparietal del grupo de dilexia comparado con el normal.

Fast ForWord y DislexiaFast ForWord; 6 a 8 semanas para un avance de 1 a 3 aos en la lectura.Programa intensivo de entrenamiento para la lectura que mejora el funcionamiento cerebral anormal de la dislexia.Programa probado en clnicas, escuelas y estudiado cientficamente en el laboratorio.

Lectores NormalesProcesamiento FonolgicoDerechoIzquierdoIzqActividadpresente en corteza temporoparietal

Trastornos de LecturaProcesamiento FonolgicoDerechoIzquierdoIzq

Dislxicos- Pre entrenamientoEfectos Cerebrales del EntrenamientoAumentoFrontal yTemporoParietal

Efectos Cerebrales del Entrenamiento: Procesamiento Fonolgico

FIGURA 1. The right panel shows a brain activation map from magnetic source imaging involving different language tasks superimposed on an anatomical magnetic resonance imaging scan. Note the significantly greater activation of the sites in the left hemisphere versus the right hemisphere, especially in the left perisylvan region. More posterior areas of the left hemisphere corresponding to Wernickes area and angular gyrus are also activated. In the right panel, activation of Wernickes area is shown inan auditory listening task. Fletcher, JM et.al., 2002

Figure 2. Left middle and inferior frontal gyrus during phoneme mapping (Talairach level: x 40). (A) Areas of greater activation for controls than children with dyslexia at the initial scan. (B) Areas of greater activation forcontrols than children with dyslexia at the follow-up scan. (C) For dyslexic subjects only: areas of greater activation at follow-up scan as compared with initial scan. (D) For control subjects only: areas of less activation atfollow-up scan as compared with initial scan. (The control subjects showed no significant increases in activation in any regions.) Regions of interest are circled in green. Arrows indicate the only regions that were more activated for control than for dyslexic subjects atfollow-up scans. (The small posterior region of activation is the same area of superior parietal lobe that is identified in figure 3B.) Right and left superior parietal region during phoneme mapping Talaraich level Z=43 Aylward, EH, et.al., 2003

DislexiaDesrden de origen constitucional, que se manifiesta con dificultades para aprender a leer, escribir o deletrear a pesar de recibir una instruccin educacional convencional, poseer inteligencia adecuada y disponer de oportunidades socio culturales.

Figure 3. Right and left superior parietalregion during phenome mapping(Talairach level: z 43): (A) Areas ofgreater activation for controls thanchildren with dyslexia at the initialscan. (B) Areas of greater activation forcontrols than children with dyslexia atthe follow-up scan. (C) For dyslexicsubjects only: areas of greater activationat follow-up scan as comparedwith initial scan. (D) For control subjectsonly: areas of less activation atfollow-up scan as compared with initialscan. (The control subjects showedno significant increases in activation inany of the regions of interest in figures2 through 5.) Regions of interest arecircled in green. Arrows indicate theonly regions that were more activatedfor control than for dyslexic subjects atfollow-up scans. NEUROLOGY 61 July (2 of 2) 2003

Figure 4. Right fusiform gyrus duringmorpheme mapping (Talairach level:y 71): (A) Areas of greater activationfor controls than children withdyslexia at the initial scan. (B) Areasof greater activation for controls thanchildren with dyslexia at the follow-upscan. (C) For dyslexic subjects only: areasof greater activation at follow-upscan as compared with initial scan. (D)For control subjects only: areas of lessactivation at follow-up scan as comparedwith initial scan. (The controlsubjects showed no significant increasesin activation in any of the regionsof interest in figures 2 through5.) Regions of interest are circled ingreen. There were no regions that weremore activated for control than for dyslexicsubjects at follow-up scans.

Figure 5. Right superior parietal regionduring morpheme mapping (Talairachlevel: y 67): (A) Areas ofgreater activation for controls thanchildren with dyslexia at the initialscan. (B) Areas of greater activation forcontrols than children with dyslexia atthe follow-up scan. (C) For dyslexicsubjects only: areas of greater activationat follow-up scan as comparedwith initial scan. (D) For control subjectsonly: areas of less activation atfollow-up scan as compared with initialscan. (The control subjects showedno significant increases in activation inany of the regions of interest in figures2 through 5.) Regions of interest arecircled in green. Arrows indicate theonly regions that were more activatedfor control than for dyslexic subjects atfollow-up scans.July (2 of 2) 2003 NEUROLOGY 61 217

Instructional treatment associatedwith changes in brain activation inchildren with dyslexiaE.H. Aylward, PhD; T.L. Richards, PhD; V.W. Berninger, PhD; W.E. Nagy, PhD; K.M. Field, BA;A.C. Grimme; A.L. Richards, BS; J.B. Thomson, PhD; and S.C. Cramer, MD

NEUROLOGY 2003;61:212219

Abnormal Activation of Temporoparietal Language Areas DuringPhonetic Analysis in Children With DyslexiaJoshua I. Breier, Panagiotis G. Simos, Jack M. Fletcher, Eduardo M. Castillo, Wenbo Zhang, andAndrew C. PapanicolaouThe University of Texas Health Science Center at Houston

Neuropsychology Copyright 2003 by the American Psychological Association, Inc.2003, Vol. 17, No. 4, 610621

Figure 2. Individual magnetoencephalography scans from a child in the group with no impairment (NI; top) and a child in the group with dyslexia (bottom). Late activity sources (i.e., those occurring after 200 ms poststimulus onset) are represented by orange circles. As can be seen, the NI profile consists of a well-formed map of activity in the left temporoparietal region with relatively reducedactivity in homotopic areas of the right hemisphere. In contrast, the profile associated with dyslexiaconsists of a well-formed map in the right temporoparietal region with equivalent but more diffuse activity in homotopic areas of the left hemisphere.

Magnetic Source ImagingDetects small bio-magnetic brain signalsProvides real-time information about which brain areas are active and when during task performance

Neural Response to InterventionDoes the pattern of brain activation change in response to intervention?8 children with severe dyslexia (7 to 17)8 week intense phonologically- based intervention (2 hours a day= up to 80 hours of instruction)Very large improvements in reading ability

Simos et al., Neurology, 2002

Early Development of Reading Skills: A Cognitive Neuroscience ApproachJack M. Fletcher PI

Students were identified as at risk for reading difficulties in kindergarten

Received one year of intervention in first grade

S#1S#31Kindergarten

Kindergarten

First GradeLeftRightAt Risk Reader before and after treatment

Summary: neuro-imaging studiesIn young children, powerful instruction can lead to more typical patterns of brain activation for reading in at-risk children- increase in left temporo-parietal, reduction in right hemisphere activation (Simos, et al., 2002; Fletcher, 2003)Another study that provided less intervention, also produce increased activation in analogous areas in the right hemisphere (Temple, et al., 2003)In adults , successful interventions do not produce changes in typical areas of left hemisphere, but produce increased activation in analogous areas of right hemisphere (Eden, in press)

AnteriorIzquierdaDislexiaControl AnteriorDerechaImgenes de espectroscopa funcional de Resonancia Magntica durante una tarea fonolgica. Las cajas blancas muestran las reas de activacin cerebral medidas por los cambios en lactato cerebral. La imagen en la izquierda es de un sujeto dislxico, La imagen de la derecha es de un voluntario normal. El lado izquierdo del sujeto esta en el lado derecho de la imagen (una convencin radiolgica). Nota la gran activacin en la zona anterior izquierda del cerebro del sujeto dislxico. Este tipo de diferencia es especfica a la tarea fonolgica. (Datos de la University of Washington Learning DisabilityCenter)

Las siguientes dos diapositivas muestran las diferenciasDe imgen cerebral entre los dislxicos y controles duranteUna tarea lxica utilizando Resonancia Magntica funcional. Los crculos blancos muestran las reas de de activacin cerebral edida por la oxigenacin de la sangre. Nota como todos los 6 sujetos normales tienen activacin en la nsula (valo superior) y en el lbulo temporal (valo inferior). ninguno de los sujetos dislxicos mostraron activacin en lansula y tuvieron activacin inconsistente en el lbulo temporal. (Data from the University of Washington Learning DisabilityCenter)

Dislxicos Tarea lxica