Neuroanatomy of Dyslexia: a Behavioral-anatomic Study of Dyslexia Subtypes and Controls

Even though dyslexia is the most common kind of learning disability, after a century of study, there is still no agreement on the definition, subtypes, and characteristics. Researchers speculate that anomalies of asymmetry in language areas in the brain may be related to disruption in the development of the brain and, thus, may contribute to language processing disorders, including dyslexia. This study investigated cognitive, behavioral and anatomic correlations of dyslexia using magnetic resonance imaging (MRI) to investigate six gross lobar regions. Results indicated 11% larger prefrontal lobes in Dyslexics than Controls. Additionally, the broad groups of Controls and Dyslexics were categorized into five subgroups. Although small, these subgroups demonstrated significant differences on every cognitive and behavioral measure. This offers new directions for future research using subtypes which may be more revealing and explain earlier inconsistent findings. This research is of interest to educational and scientific researchers who are investigating cognitive, behavioral and/or anatomical correlates of dyslexia.