Corpus callosum view, front part at top of image For most people who are right-hand dominant, the left hemisphere of their brain is more specialized for language processing. With regard to the mechanism of<unk> , fMRI studies suggest that this specialization is less pronounced or absent in people with<unk> . In other studies,<unk>  is correlated with anatomical differences in the corpus callosum, the bundle of nerve fibers that connects the left and right hemispheres. Data via diffusion tensor MRI indicate changes in connectivity or in gray matter density in areas related to reading and language. Finally, the left inferior frontal gyrus has shown differences in phonological processing in people with<unk> . Neurophysiological and imaging procedures are being used to ascertain phenotypic characteristics in people with<unk> , thus identifying the effects of<unk> -related genes. Dual route theory The dual-route theory of reading aloud was first described in the early 1970s. This theory suggests that two separate mental mechanisms, or cognitive routes, are involved in reading aloud. One mechanism is the lexical route, which is the process whereby skilled readers can recognize known words by sight alone, through a "dictionary" lookup procedure. The other mechanism is the nonlexical or sublexical route, which is the process whereby the reader can "sound out" a written word. This is done by identifying the word's constituent parts (letters, phonemes, graphemes) and applying knowledge of how these parts are associated with each other, for example, how a string of neighboring letters sound together. The dual-route system could explain the different rates of<unk>  occurrence between different languages (e.g., the consistency of phonological rules in the Spanish language could account for the fact that Spanish-speaking children show a higher level of performance in non-word reading, when compared to English-speakers).
Dyslexia
Hearing loss
Diplophonia
Visual impairment
Dysgraphia
Reading
Social-emotional agnosia
Misophonia