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Abstract:
To begin a study of language development, child-appropriate
lexical tasks were designed and then tested in adults and children
using event-related fMRI. Tasks were "controlled" (verb, opposite,
rhyme generation) or "simple" (repeat, read) with visual or
auditory input, and vocal responses. Task vocabulary was
appropriate for 6-7 year-old readers. Twenty-one normal adults
(20-34 yrs, 11 female, all right-handed) and 23 normal children
(7.5-10.5 yrs, 12 female, 3 left-handed) were scanned using ASE-EPI
sequences for BOLD data acquisition. Responses were recorded and
reaction times measured. Children and adults performed reasonably
on all tasks. Adults engaged regions seen in similar studies when
the vocabulary was adult-appropriate. Regions included, but were
not limited to, bilateral supplementary motor area, premotor and
motor cortex in all tasks, striate/extrastriate in visual tasks,
left inferior frontal gyrus in controlled tasks. Children imaged in
an identical fashion had largely similar regions of activation.
However, a region in dorsal frontal cortex, consistently seen in
adults performing controlled tasks, was engaged significantly less
in children. By contrast, a region in medial occipital gyrus,
engaged by children, was engaged significantly less in adults.
These findings suggest that systematic differences exist between
the sets of brain regions used by adults and children performing
controlled lexical processing tasks. (NIH: NSADA55582, NS32979,
NS06833, CHRCHD33688; McDonnell Center for Higher Brain
Function)
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