Brain imaging in neurobehavioral disorders

Neuroimaging studies of neurobehavioral disorders are using new imaging mod alities. In dyslexia, anatomic imaging studies demonstrate an abnormal symm etry of the planum temporale. Functional imaging supports the hypothesis th at developmental dyslexia is frequently the result of deficits in phonologi c processing and that normal reading requires a patent network organization of a number of anterior and posterior brain areas. In autism, anatomic ima ging studies are conflicting. Functional imaging demonstrates temporal lobe abnormalities and abnormal interaction between frontal and parietal brain areas. In attention-deficit-hyperactivity disorder, imaging studies suggest an abnormality in the prefrontal and striatal regions. Neuroimaging studie s are often contradictory, but trends, especially with functional imaging a nalysis, are evolving. Because neurobehavioral disorders seem to be a resul t of a dysfunction in brain circuits, no one region will be abnormal in all patients studied. Further studies with well-defined patient populations an d appropriate activation paradigms will better elucidate the pathophysiolog y of these conditions. (C) 2001 by Elsevier Science Inc. All rights reserve d.