Cerebral Asymmetry in Developmental Dyslexia

Haslam, Robert H. A.; Dalby, J. Thomas; Johns, Robert D.; Rademaker, Alfred

doi:10.1001/archneur.1981.00510110039003

Cited by 89 publications

(56 citation statements)

References 19 publications

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“…In contrast, dyslexics showed little asymmetry over the whole occipital lobe, and a rightward asymmetry of activity in the lingual lobule. These findings correspond well with the reduced structural posterior asymmetry that has been observed in CT and post-mortem studies of dyslexics' brains (Galaburda & Kemper, 1979;Galaburda et al, 1985;Haslam et al, 1981;Hier et al, 1979).…”

Section: Discussionsupporting

confidence: 79%

Positron emission tomographic studies during serial word-reading by normal and dyslexic adults

Gross-Glenn

Duara

Barker³

et al. 1991

Journal of Clinical and Experimental Neuropsychology

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Positron-emission tomography (PET) was used to study regional cerebral metabolic activity during oral reading in right-handed adult males with, and without a childhood and family history of developmental dyslexia. Significant group differences in normalized regional metabolic values were revealed in prefrontal cortex and in the lingual (inferior) region of the occipital lobe. Lingual values were bilaterally higher for dyslexic than normal readers. In contrast to the asymmetry observed in prefrontal and lingual regions in nondyslexic subjects during reading, the dyslexic pattern was more symmetric. These results demonstrate that individuals who suffered from familial developmental dyslexia as children, activate different brain regions during reading as adults, as compared to individuals without such childhood history.

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Section: Discussionsupporting

confidence: 79%

Positron emission tomographic studies during serial word-reading by normal and dyslexic adults

Gross-Glenn

Duara

Barker³

et al. 1991

Journal of Clinical and Experimental Neuropsychology

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“…No gross brain pathology has ever been uncovered in even well defined large samples of reading disabled children using such techniques as CAT scans (Haslam et al, 1981). Anatomical nuances are extremely common in sexually-reproducing species.…”

mentioning

confidence: 99%

Note: An ultimate view of reading ability

Dalby

1986

International Journal of Neuroscience

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Research on reading and developmental reading disorders has almost exclusively questioned the immediate or proximate basis of these skills and deficits. A supplementary view is offered that considers reading ability from an evolutionary vantage. It is argued that in contrast to language, which has a long natural history in man and which has risen from a widespread biological adaptation in our species, reading has not, until very recently, exerted ecological pressure on humans and therefore no specific biological adaptations have occurred for these skills. It follows that developmental reading disorders may be due to genetically based, naturally occurring variants in neurological traits and not the result of pathological processes.

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“…This finding was later replicated in a larger group of subjects with learning disabilities [Rosenberger and Hier, 1980]. Another CT study failed to replicate the IQ effect although an increased prevalence of symmetrical occipital widths was found in the RD group [Haslam et al, 1981].…”

Section: A Brief Historymentioning

confidence: 91%