Article

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. 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.

Langue : ANGLAIS