Attend a conference on the topic of dyslexia

I contacted Ms. ASTA LEE, an art therapist in Singapore, who invited me to attend a recent talk on dyslexia, which focused on the causes of dyslexia

Around the second half of the last century, research on dyslexia reached a new impetus from histo-pathological and neuroimaging studies. For the first time, autopsy studies on the brain of developmental dyslexics showed a bilaterally large temporal planum, and the absence of the planum temporal asymmetry. ition, such studies found, in the whole brain, cytoarchitectonic abnormalities, such as ectopic collections of neurons in layer one of the cortex, especially in perisylvian areas, in the thalamus lateral geniculate nucleus of the visual pathway and in the medial geniculate nucleus of the auditory pathway. Such cortical anomalies were more frequent in the areas surrounding Silvio’s fissures, in the left hemisphere, roughly corresponding to the frontal and temporal language areas.

Both reduced planum temporal asymmetry and cortical malformations suggest an anomalous brain development, in prenatal stages of corticogenesis, with abnormally high levels of surviving neurons, as a significant neuroanatomical association to developmental dyslexia.

Such abnormal neural migration affects the pattern of connectivity within and between the hemispheres, especially with the thalamus, ipsilateral and contralateral cortex and alters the development of these brain areas. Neuron ectopic collections may be associated with a developmental anomaly of the adjacent cortical layers (dysplasia).

Along with dysplasia and cortical ectopias, vascular anomalies often resemble small micro angiomas and sometimes arterio-venous malformations. Neuroradiological studies also showed a link between dyslexia and arteriovenous malformations, especially in males and in the left superior temporal areas.

Post-mortem and neuro-imaging studies provided strong neuroanatomical evidence on the structural and morphologic differences between normal and dyslexic brains, giving a cogent contribution to understanding the neural and cognitive basis of developmental dyslexia as a language- based disorder.