http://nnr.sagepub.com/content/26/7/870.abstract?etoc
Abstract
Background. Given that traumatic brain
injury (TBI) results in chronic alteration of baseline cerebral
perfusion, a perfusion functional
MRI (fMRI) method that dissociates resting- and
task-related cerebral blood flow (CBF) changes can be useful in
noninvasively
investigating the neural correlates of cognitive
dysfunction and recovery in TBI. Objective. The authors used
continuous arterial spin-labeled (ASL) perfusion fMRI to characterize
CBF at rest and during sustained-attention
and working-memory tasks. Methods. A total
of 18 to 21 individuals with moderate to severe TBI and 14 to 18
demographically matched healthy controls completed
3 continuous 6-minute perfusion fMRI scans
(resting, visual sustained attention, and 2-back working memory). Results.
For both tasks, TBI participants showed worse behavioral performance
than controls. Voxelwise neuroimaging analysis of the
2-back task found that group differences in
task-induced CBF changes were localized to bilateral superior occipital
cortices
and the left superior temporal cortex. Whereas
controls deactivated these areas during task performance, TBI
participants
tended to activate these same areas. These regions
were among those found to be disproportionately hypoperfused at rest
after
TBI. For both tasks, the control and TBI groups
showed different patterns of correlation between performance and
task-related
CBF changes. Conclusions. ASL perfusion
fMRI demonstrated differences between individuals with TBI and healthy
controls in resting perfusion and in
task-evoked CBF changes as well as different
patterns of performance-activation correlation. These results are
consistent
with the notion that sensory/attentional modulation
deficits contribute to higher cognitive dysfunction in TBI.
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