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Abstract:
Abstract: Early neurodevelopmental disturbances in autism may
affect emerging neurofunctional maps, but relevant imaging evidence
is scant. We performed echoplanar imaging with 8 male autistic
patients (aged 15-39 years) and 8 age, sex, and handedness matched
normal controls during visually paced index finger movement,
compared in a blocked design to a visuoperceptual control
condition. Images were analyzed using SPM, including motion
correction, spatial normalization, and a t-statistic (with a
smoothed boxcar model, shifted to correct for hemodynamic latency).
Spatially normalized data showed expected activation in
contralateral perirolandic cortex, bilateral supplementary motor
areas, and contralateral basal ganglia for both groups. However,
spatial extent of significant activations and peak Z scores were
reduced in the autism group. Quantification of head motion ruled
out motion confounds as an explanation. Analyses in native space
(with Z maps coregistered to high-resolution structural images)
showed that loci of major activations were highly consistent across
individual normal controls, but variable in the autism group, with
individual autistic subjects showing significant activation outside
canonical motor regions. Furthermore, the normal control group
showed extensive deactivation in temporo-parieto-occipital regions,
which was absent in the autism group. Our findings may relate to
reported motor impairments in autism and are compatible with the
general hypothesis of atypical functional maps and incomplete
functional differentiation in the autistic cerebrum.
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