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November 1987

Regional Cerebral Blood Flow in Severe Developmental Dyslexia

Author Affiliations

From the Child Psychiatry Branch (Drs Rumsey and Kruesi and Ms Hamburger), Clinical Brain Disorders Branch, Neuropsychiatry Branch (Drs Berman and Weinberger), National Institute of Mental Health, and Developmental Neurology Branch (Dr Denckla), National Institute of Neurological and Communicative Diseases and Stroke, Bethesda, Md.

Arch Neurol. 1987;44(11):1144-1150. doi:10.1001/archneur.1987.00520230034010

• Regional cerebral blood flow was measured under three task conditions in 14 men with severe developmental dyslexia and their control subjects using a xenon 133 inhalation technique. No group differences in overall level or in pattern of gray matter flow were seen under relatively undemanding cognitive conditions. Despite minimal group differences in performance, the dyslexic group showed an increased hemispheric asymmetry (left greater than right) on a semantic classification task and a reduced anteroposterior difference on a line orientation task relative to controls. The exaggerated asymmetry suggests the possibility of less efficient information processing or inadequate bihemispheric integration. The reduced anteroposterior gradient may reflect a deficit in the ability of frontal systems to respond adequately to cognitive demands.

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