Neurobiological correlates of learning disabilities

AbstractMost investigator now agree on the existence of abnormalities of brain function in children with learning disabilities with or without hyperactivity. However, attempts to define the neurobiological substrates have been hindered by many factors. On the clinical level, learning disability is not a monolithic entity but an operational term used to define a number of specific conditions. The only common feature is difficulty with school performance in the face of normal intelligence. Until homogeneous subgroups can be defined, there is no good reason to suspect a single, discrete biological marker.Neuropathological studies are limited to 2 cases. Attempts to visualize the brain by computerized tomography have provided limited but inconsistent evidence of variations from normal hemispheric widths and asymmetries. Neurophysiological studies have succeeded in separating learning disabled children from normal controls by the application of discriminant analysis and other statistical techniques. Computer‐assisted analysis of brain bioelectrical activity has sharpened these tools. Unfortunately, the techniques have not been able to narrow the focus to single, discrete cerebral areas;