[Specific reading disorders and the neurobiology of speech]

Abstract

Overview of views on dyslexia-specific reading disorders. The most important contribution to the problem was the work of S. T. Orton which began more than 60 years ago. He was the first to formulate the neuropsychological theory of dyslexia. His followers use as a basis his idea that the specific background of dyslexia are cerebral mechanisms with decisive functional relations of the two cerebral hemispheres, but they abandon the factor of dominance of one half of the cerebral cortex. An important contribution was the work of D. Kimura et al. (some 30 years ago) who published findings relating to the role of the hemispheres in processing different grades of human speech, spatial, superficial and figural stimuli (inc. text). During the last twenty years interesting findings were provided by child neurologists R. Masland, N. Geschwind and his pupil and follower A. Galaburda (cytoarchitectonic investigations of the brain) and the neurosurgical clinic of Prof. G. A. Ojeman. Thus a new discipline was developed--neurobiology of speech as well as other branches of so-called neurosciences. Their findings will influence in future not only the approach to handicapped children but also the organization of the training process and teaching methods.