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Abstract:
Abstract: Despite extensive research, it is still unclear
whether hemispheric specialisation for language is present at birth
or emerges gradually during childhood. Studies of children with
extensive left hemisphere injury indicate that speech and language
functions are often rescued, suggesting that the spared abilities
are most likely subserved by the intact right hemisphere. We
investigated speech and language functions in patients who had
undergone hemispherectomy consequent to epileptic disorders that
were acquired during early (before 5 years) and late (after 5
years) childhood. Nine left and 11 right hemispherectomized
patients were assessed on tests of intelligence, object naming,
expressive vocabulary, receptive vocabulary, receptive grammar, and
language comprehension. Results indicate that in both groups,
verbal and nonverbal IQ scores are lowered by about 30 points
relative to the population mean. Left hemispherectomy resulted in a
selective impairment on verbal IQ and expressive vocabulary, but
this difference was significant only in the late pathology group.
Once corrected for verbal IQ, the scores of the right and left
hemispherectomized patients on the other language tests did not
differ. These data indicate that left hemisphere specialisation for
verbal intelligence develops gradually during childhood, whilst
other aspects of speech and language can be subserved equally well
by either hemisphere.
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