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Abstract:
Abstract: Studies show increased head circumference or brain
volume in autistic patients. We've found abnormal enlargement of
the cerebrum and abnormal cerebral growth rates in autistic
children. Here, we determined whether these effects were limited to
particular lobes of the cerebrum. Manual and automated MRI methods
were used to delimit boundaries of the frontal lobe (FL), occipital
lobe (OL), and combined temporal and parietal lobes (T-PL). In
2-4.5 year olds, FL and T-PL volumes were larger (14%, 12%) in
autism. This abnormality was not as apparent in the OL (8%, n.s.).
Subjects aged 4.5-7.5 and 7.5-11.5 showed no difference between
groups (<= 3%). The contrasting findings in different age
groups may be due to abnormal growth rates: In controls, FL &
T-PL volumes increased substantially (19%, 14%) from the first age
group to the second. This growth was not seen in the autism
subjects (22%). Growth was somewhat less in normal OL (8%) and was
absent in autism (0%). So, in autism, cerebral lobes show abnormal
growth rates, with early overgrowth followed by a lack of the
continued growth seen in normals. Effects may be smaller in OL, or
may follow a different time course. Alterations in the degree or
timing of growth processes in autism, particularly in association
areas, are likely to have repercussions for later aspects of
neurodevelopment and for ultimate function of the regions.
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