[Dyslexia-dysorthographia; presentation of a case-finding test and control with emphasis on a dyslexia index].
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The classic pathognomic signs of dyslexia, such as reversals and rotations, appear to be associated with poor reading, not diagnosed developmental dyslexia. 26 8th and 9th grade dyslexia with poor perceptual/attentional ability were matched with 19 reading-retarded subjects with age-equivalent perceptual/attentional test scores for age, IQ, and degree of reading retardation and compared both with each other and with 96 adequate readers for reversals, rotations, insertions, substitutions, omissions, poor handwriting and visual ability on the Gray test, the WRAT Spelling Test, a writing task, and the star-tracing mirror test. On 46 of 49 variables, the dyslexia and retarded readers performed comparably. Together they made more classic errors and had lower achievement scores than the adequate readers on 44 of 49 variables. Classic errors clustered with poor reading but not diagnosed dyslexia. The hypothesis that reading acquisition trains perceptual test-taking ability is advanced.
An analytical investigation of the residual reading capacities of a single patient with dyslexia without dysgraphia is reported. Both his ability to name and to comprehend letters and words were severely impaired. The major finding of this investigation was AR's striking capacity for categorizing words he could not read. In addition there was evidence of semantic priming effects. Thus AR was frequently able to achieve partial comprehension of words he could not read. The orthodox interpretation of the dyslexia without dysgraphia in terms of a disconnection syndrome is shown to be inappropriate, at least for the present case, where the deficit appears to be within the semantic domain; it is argued that this type of dyslexia is due to an impairment in accessing semantic information.
The computerized brain tomograms of 24 patients with developmental dyslexia were analyzed for cerebral asymmetry. Ten patients showed a reversal of the pattern of asymmetry regularly observed in normal right-handed individuals so that the right parietooccipital region was wider than the left. The ten dyslexic patients with this reversal of cerebral asymmetry had a lower mean verbal IQ than the other 14 dyslexic patients in this study. The reversal of cerebral asymmetry that occurred in ten of the dyslexic patients may result in language lateralization to a cerebral hemisphere that is structurally less suited to support language function and thus act as a risk factor for the development of reading disability.
Specific developmental dyslexia, a condition characterized by reduced reading, spelling, and writing abilities combined with normal intellectual capacity, has challenged geneticists and 'environmentalists.' Although most of the strikingly controversial results can be traced to differences concerning diagnostic decision-making, there are many hints of a genetic contribution. Twin studies and extensive pedigree analysis substantiate this view, but it is too early to infer a definite mode of inheritance from the available data.
Developmental dyslexia (DD) is characterised by lower-than-average reading abilities and is diagnosed in approximately 10% of individuals. The societal barriers may limit professional fulfilment and psychological wellbeing of individuals with DD, calling for the development of effective interventions to counteract them. As DD is associated with challenges in both phonological and visuo-attentional domains, different longitudinal training approaches were developed to strengthen them. However, they require a considerable amount of personal, social and economic resources and the outcomes may vary depending on individual differences in behavioural and neurophysiological functionality. Hence, predicting training outcomes might help in developing personalised treatment protocols and optimising the use of resources. In the present work we applied machine learning to resting-state EEG to predict longitudinal training outcomes in adults with DD enrolled in a randomized clinical trial. In particular, one group received a visuo-attentional training combined with transcranial alternating current stimulation (tACS), another group received visuo-attentional training with sham/placebo stimulation, and the third group received a phonological training with sham/placebo stimulation. The improvement in text reading speed was associated with spectral power in low-beta and individual frequencies in the alpha (IAF) and beta (IBF) bands, while the improvement in pseudoword reading was associated with IBF. The findings highlight the potential of capturing neural markers of treatment responsiveness in DD. Future studies should focus on the generalisability of predictive models to real-world settings, while investigating whether specific EEG markers predict responsiveness to distinct remediation protocols, thus supporting the development of personalised interventions.
The oculomotor performance of 25 dyslexic and 19 normal children was evaluated to determine whether or not dyslexia involves deficits in oculomotor function or visual perception. When the children were required to follow a meaningless target or to solve pictorial tasks, the two age-matched groups could not be differentiated. When they were required to read selections commensurate with their measured reading level, the dyslexic children were markedly different on a number of parameters. It appears that the dyslexic's difficulty lies beyond visual perception, perhaps in the language area itself. The dyslexic's characteristic deficit seems to involve the integration of visual input into the language-acquisition function.
Developmental dyslexia may be associated with (i) bi-hemisphere representation of spatial functions, in contrast to the right-hemisphere specialization observed in normal children, and (ii) typical left-hemisphere representation of linguistic functions, as is observed in normal children. The bilateral neural involvement in spatial processing may interfere with the left hemisphere's processing of its own specialized functions and result in deficient linguistic, sequential cognitive processing and in overuse of the spatial, holistic cognitive mode. This pattern of cognitive deficits and biases may lead dyslexics to read predominantly with a spatial-holistic cognitive strategy and neglect the phonetic-sequential strategy. Such an approach in learning to read phonetically coded languages, such as English, many be inefficient and limited.
After an "occipital lobectomy" that resulted in a severe dyslexia and a moderate dysgraphia-dyscalculia, anatomical study showed damage to the posterior extremity of the angular gyrus and degeneration in the posteroinferior pulvinar. This is in contrast to an earlier case that had degeneration in the anterosuperior pulvinor associated with a small anterior temporoparietal infarct and a well-documented receptive-expressive aphasia. However, the role of the pulvinar in speech function remains uncertain. The surgeon should be aware of the short distance between the angular gyrus and both the midline and the occipital pole because a lesion here during an "occipital lobectomy" produces a distressing and durable speech impairment.
Recent advances in the understanding of the asymmetrical functions of the cerebral hemispheres provide new insight to the mechanisms underlying the developmental language disorders. It is probable that learning to read depends in part upon the ability to establish an association between a seen object (customarily perceived within the right hemisphere) and a verbal symbol (mediated by the left). It is possible that as the reading skill develops, verbal symbol recognition may also become a left hemisphere function. A complex interaction between the two developing hemispheres is involved. A clue to the nature of this problem is that developmental dyslexia is six times more common in boys than in girls. Studies defining differences in cerebral dominance in boys and girls will be reviewed in this context.
37 children with a mean reading retardation of 4,3 years were placed full time in a specialized centre. All had failed in school in spite of remedial training and/or psychotherapy. The goal of the centre is to separate linguistic and non-linguistic subjects. The non-linguistic subjects were taught with the aid of audio-visual methods in order to relieve the dyslexics of the burden of written language. If progress with reading and spelling was slow, audio-visual instruction enabled these children to reach or exceed 5th grade level in non-linguistic subjects. 80% of them were able to go on to vocational schools. At the same time, there was a very favorable improvement in their behavior (P less than 0.001), which is a prerequisite in the prevention of juvenile delinquency and an essential step in social and professional integration. These favorable results emphasize the part audio-visual instruction should play in severe dyslexia.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.