The Neuropsychological Basis of Learning Disabilities
George W. Hynd Amanda B. Clinton Jennifer R. Hiemenz
Learning disabilities are most appropriately viewed from a neuropsychological perspective. This perspective is consistent with the history of over a century of clinical and experimental reports and with accepted definitions of learning disabilities, which typically tie these disabilities to central nervous system dysfunction ( Harris & Hodges, 1981; Hynd, Hooper, & Takahashi, in press). It is believed that the behavioral characteristics we associate with learning disabilities arise from abnormalities or variance in the development of important brain structures and associated connections among neurons in the cerebral cortex, which most likely arise between the fifth and seventh month of fetal gestation ( Galaburda, 1993; Hynd & Semrud-Clikeman, 1989).
This chapter addresses the conceptualization of learning disabilities, particularly in the area of reading, as arising from neurological deficits. This conceptualization is based on studies of documented variability in the brains of individuals diagnosed with learning disabilities in reading. The focus herein is based on a long history of inquiry into this specific learning disability. Unfortunately, considerably less is known about other learning disabilities such as in written language or mathematics.
Various methods of investigation have been used in examining these anatomical anomalies, including postmortem procedures, neuroimaging
This research was supported in part by a grant (RO1-HD26890-03) awarded to the first author from the National Institute of Child Health a nd Human Development (NICHHD), National Institutes of Health (NIH).