This research study was undertaken to test a model of posterior displacement of focal perisylvian activation based on the autopsy work of Galaburda, the intraoperative work of Ojemann and Rasmussen, and neural developmental animal work. By this model, an early lesion in Wernicke's area would displace some aspects of the neuronal processing capacity originally destined for Wernicke's area to adjacent, posterior cites. Forty-one normal adult males and 47 adult males with documented childhood reading evaluations (the Orton group) performed an orthographic analysis (spelling) task. Some also did phonetic and tonal tasks. Regional cerebral blood flow was measured during task performance using the 133-Xenon inhalation method. Normal subjects showed cerebral activation at left Wernicke's area proportional to spelling task accuracy, while Orton subjects showed activation both at Wernicke's area and at the left angular gyrus such that better performers of the spelling task activated Wernicke's area more and angular gyrus less. An inverse relationship between childhood reading impairment and angular gyrus activity also was found, and this was independent of either task accuracy or adult reading attainment
