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Abstract:
Our previous studies using transcranial Doppler sonography
and SPECT have revealed reduced blood flow in patients with
Huntington's disease (HD) during maze testing within orbitofrontal
cortex and the caudate nucleus (Deckel et al., J Nucl Med 2000).
The current study compared fMRI in 4 right-handed early-stage
(Stages I-II) HD gene positive patients and 4 matched controls.
Subjects were asked to solve Porteus maze stimuli (maze condition),
maze stimuli with a dotted line that exited the maze (trace
condition), and maze-like stimuli with fixation point (fixation
condition), using an MRI-compatible trackball. Whole-brain
echo-planar MRI data (TR=4 sec, 36 slices, 4 mm cubic voxels) were
acquired. Data were corrected for movement using SPM. All subjects
showed increased signal bilaterally in visual cortex, superior
frontal gyri and left somatomotor cortex during performance of the
trace and maze conditions relative to fixation. Greater signal was
observed in HD- subjects relative to HD+ bilaterally in the
caudate, cerebellar vermis and thalamus, and in the orbitofrontal,
posterior parietal and cingulate gyri. Greater signal was observed
in HD+ relative to HD- in the lateral cerebellum, hippocampus,
anterior insula and the inferior and middle frontal gyri
bilaterally. These results, together with our previous findings,
indicate that responses during maze testing are altered in HD
patients. This may result from differences in neural activation
and/or cerebral hemodynamics associated with this disorder.
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