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Titolo:
The neurological basis of developmental dyslexia - An overview and workinghypothesis
Autore:
Habib, M;
Indirizzi:
CHU Timone, Dept Neurol, Cognit Neurol Lab, F-13385 Marseille, France CHU Timone Marseille France F-13385 eurol Lab, F-13385 Marseille, France
Titolo Testata:
BRAIN
, volume: 123, anno: 2000,
parte:, 12
pagine: 2373 - 2399
SICI:
0006-8950(200012)123:<2373:TNBODD>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
POSITRON EMISSION TOMOGRAPHY; PLANUM TEMPORALE ASYMMETRY; SPEECH-PERCEPTION DEFICITS; LEARNING-IMPAIRED CHILDREN; QUANTITATIVE-TRAIT LOCUS; ACOUSTICALLY MODIFIED SPEECH; CORPUS-CALLOSUM MORPHOLOGY; EVENT-RELATED POTENTIALS; CEREBRAL BLOOD-FLOW; READING-DISABILITY;
Keywords:
dyslexia; brain imaging; phonology; temporal processing; reading;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
204
Recensione:
Indirizzi per estratti:
Indirizzo: Habib, M Inst Univ Geriat, Ctr Rech, 4565 Ch Queen Mary, Montreal, PQ H3W 1W5, Canada Inst Univ Geriat 4565 Ch Queen Mary Montreal PQ Canada H3W 1W5 da
Citazione:
M. Habib, "The neurological basis of developmental dyslexia - An overview and workinghypothesis", BRAIN, 123, 2000, pp. 2373-2399

Abstract

Five to ten per cent of school-age children fail to learn to read in spiteof normal intelligence, adequate environment and educational opportunities. Thus defined, developmental dyslexia thereafter referred to as dyslexia) is usually considered of constitutional origin, but its actual mechanisms are still mysterious and currently remain the subject of intense research endeavour in various neuroscientific areas and along several theoretical frameworks. This article reviews evidence accumulated to date that favours a dysfunction of neural systems known to participate in the normal acquisition and achievement of reading and other related cognitive functions. Historically, the first arguments for a neurological basis of dyslexia came from neuropathological studies of brains from dyslexic individuals. These early studies, although open to criticism, for the first time drew attention towardsa possible abnormality in specific stages of prenatal maturation of the cerebral cortex and suggested a role of atypical development of brain asymmetries. This has prompted a large amount of subsequent work using in vivo imaging methods in the same vein. These latter studies, however, have yielded less clear-cut results than expected, but have globally confirmed some subtle differences In brain anatomy whose exact significance is still under investigation. Neuropsychological studies have provided considerable evidence that the main mechanism leading to these children's learning difficulties is phonological in nature, namely a basic defect in segmentimg and manipulating the phoneme constituents of speech. A case has also been made for impairment in brain visual mechanisms of reading as a possible contributing factor. This approach has led to an important conceptual advance with the suggestion of a specific involvement of one subsystem of vision pathways (the so-called magnosystem hypothesis). Both phonological and visual hypotheses have received valuable contribution from modern functional imaging techniques. Results of recent PET and functional MRI studies are reported here in some detail. Finally, one attractive interpretation of available evidence points to dyslexia as a multi-system deficit possibly based on a fundamental incapacity of the brain in performing tasks requiring processing of brief stimuli in rapid temporal succession. It is proposed that this so-called 'temporal processing impairment' theory of dyslexia could also account for at least some of the perceptual, motor and cognitive symptoms very often associated with the learning disorder, a coincidence that has remained unexplainedso far.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 22/01/20 alle ore 19:08:31