Dyslexia - cultural differences or universal origin?

Abstract

In this paper, we attempt to address and reconcile the differences between the apparent incompatibility between behavioural and neuroimaging findings in the field of dyslexia. Specifically, we examined research findings on the similarities and differences in the manifestation of various deficits shown by readers from different cultures. This then led us to explore the neurological basis of dyslexia. While it first appears that the underlying neurological basis of dyslexia is non-universal as evident by research findings indicating different activations of brain regions for dyslexics from different cultures, recent findings have provided strong evidence that these inconsistent findings may be due to methodological differences and that dyslexia does have a universal neurological basis. This suggests that the differences in the behavioural symptoms of dyslexic readers from different cultures are not due to neurological differences but can possibly be attributed to the different characteristics of individual language system. In other words, as normal readers from different cultures are able to specialize in their culture’s language systems, they show different brain activations. On the other hand, dyslexic readers are unable to specialize in their own language systems and therefore, they share common brain activations. In sum, dyslexia is manifested in different behavioural forms across different cultures only because each language system has its own unique characteristics. More importantly, a review of current literature has led us to conclude that the underlying basis of dyslexia has a universal neurological origin.