The development of reading impairment: A cognitive neuroscience model

This review discusses recent cognitive neuroscience investigations into the biological bases of developmental dyslexia, a common disorder impacting approximately 5 to 17 percent of the population [Rutter, 1978, I. Prevalence and types of dyslexia. In: Benton A, Pearl D (eds.), Dyslexia: An appraisal of current knowledge. New York: Oxford; Stanovich, 1986, Matthew effects in reading: Some consequences of individual differences in the acquisition of literacy. Reading Research Quarterly 21: 360-407]. Our aim is to summarize central findings from several lines of evidence that converge on pivotal aspects of the brain bases of developmental dyslexia. We highlight ways in which the approaches and methodologies of developmental cognitive neuroscience that are addressed in this special issue-including neuroimaging, human genetics, refinement of cognitive and biological phenotypes, neural plasticity and computational model-can be employed in uncovering the biological bases of this disorder. Taking a developmental perspective on the biological bases of dyslexia, we propose a simple cascading model for the developmental progression of this disorder, in which individual differences in brain areas associated with phonological processing might influence the specialization of visual areas involved in the rapid processing of written words. We also discuss recent efforts to understand the impact of successful reading interventions in terms of changes within cortical circuits associated with reading ability. (C) 2003 Wiley-Liss, Inc.