ABSTRACT
In this study we investigated the neural correlates of acquired reading disorders through an anatomo-correlative procedure of the lesions of 59 focal brain damaged patients suffering from acquired surface, phonological, deep, undifferentiated dyslexia and pure alexia. Two reading tasks, one of words and nonwords and one of words with unpredictable stress position, were used for this study. We found that surface dyslexia was predominantly associated with left temporal lesions, while in phonological dyslexia the lesions overlapped in the left insula and the left inferior frontal gyrus (pars opercularis) and that pure alexia was associated with lesions in the left fusiform gyrus. A number of areas and white matter tracts, which seemed to involve processing along both the lexical and the sublexical routes, were identified for undifferentiated dyslexia. Two cases of deep dyslexia with relatively dissimilar anatomical correlates were studied, one compatible with Coltheart's right-hemisphere hypothesis (1980) whereas the other could be interpreted in the context of Morton and Patterson's (1980), multiply-damaged left-hemisphere hypothesis. In brief, the results of this study are only partially consistent with the current state of the art, and propose new and stimulating challenges; indeed, based on these results we suggest that different types of acquired dyslexia may ensue after different cortical damage, but white matter disconnection may play a crucial role in some cases.
Subject(s)
Brain Diseases/pathology , Brain Injuries/pathology , Dyslexia, Acquired/pathology , Frontal Lobe/pathology , Models, Neurological , Temporal Lobe/pathology , White Matter/pathology , Adolescent , Adult , Aged , Aged, 80 and over , Brain Diseases/complications , Brain Diseases/physiopathology , Brain Injuries/complications , Brain Injuries/physiopathology , Brain Ischemia/complications , Brain Ischemia/pathology , Brain Ischemia/physiopathology , Brain Mapping , Cerebral Hemorrhage/complications , Cerebral Hemorrhage/pathology , Cerebral Hemorrhage/physiopathology , Dyslexia, Acquired/classification , Dyslexia, Acquired/etiology , Dyslexia, Acquired/physiopathology , Female , Frontal Lobe/physiopathology , Functional Neuroimaging , Humans , Language , Magnetic Resonance Imaging , Male , Middle Aged , Psycholinguistics , Reading , Temporal Lobe/physiopathology , White Matter/physiopathology , Young AdultABSTRACT
A permanent health education campaign was begum some months ago among air force personnel designed to persuade men of all functions and ranks and suffering from refraction defects, to use prescribed corrective means permanently. The causes of failure to use them on the part of many subjects are analysed and the desirability of the health education campaign and the most suitable means of conducting it are illustrated.
