rCBF activation in a patient with right homonymous hemianopia and alexia without agraphia

Does dyslexia develop from learning the alphabet in the wrong hemisphere? A cognitive neuroscience analysis

A new perspective is described which views developmental dyslexia as the outcome of learning to write the alphabet in the nondominant (right) hemisphere. The letter-level and whole-word subtypes of dyslexia are seen as differing responses adopted to cope with this predicament. Striking similarities between dyslexics and callosotomy patients in the allocation of covert attention to lateralized stimuli provide direction for integrating a diversity of dyslexic research within this framework. This synthesis, together with information from pure alexia, brain activation, and reading research, lends insight into the neural circuitry of the compensatory strategies adopted by the two dyslexic subtypes.

Dyslexia: two priorities for the 1980s

Within the past decade significant advances have been made in articulating the unique neuropsychological and cognitive processes in dyslexic children. The brain mapping procedures and postmortum studies are especially important in this regard. However, two important issues remain largely unaddressed. First, to date, no recognized nosology for dyslexia or subtypes of dyslexia exist. Second, the functional neurolinguistic system involved in reading and severe reading failure is, as of yet, still not completely understood in regard to subtypes of dyslexia. This article discusses these two areas of priority and proposes a framework for addressing these areas of concern.