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| Publication Abstract Display | | Type: Published Abstract | | Title: Altered DLPFC intrinsic connectivity in chronic HIV. | | Authors: Ipser JC, Bischoff-Grethe A, Brown GG, Connolly CG, Jordan SJ, Grant I, and the TMARC group | | Year: 2012 | | Publication: 3rd Biennial on Resting State Brain Connectivity | | Volume: Issue: Pages: | | Abstract:Introduction & Aims: HIV infection is associated with an increased risk of deficits in cognitive abilities subserved by frontostriatal neural circuitry, with evidence of functional connectivity abnormalities in the dorsolateral prefrontal cortex (DLPFC). The objective of this study was to characterize patterns of DLPFC-referenced BOLD synchronicity during a task-free condition in subjects who have chronic HIV, relative to healthy controls.
Method: Whole-brain 3T T2-weighted images were acquired while subjects participated in a 6.5 minute eyes-open task-free protocol. Left and right DLPFC masks were used as seed ROIs for functional intrinsic connectivity analysis in 17 HIV patients and 8 age and education-matched healthy controls. On an individual subjects level, B0 correction, tissue segmentation and temporal co-registration was followed by physiological and residual motion artifact removal and hemisphere-specific within-subject averaging of the BOLD signal in the DLPFC. Subject brains were subsequently registered to Talairach space for group comparisons and smoothed with a 7mm gaussian kernel. Within-group and between-group t-tests of Fischer z-transformed correlations were conducted for both the left and right DLPFC, with moderating effects of age, education and cognitive impairment tested in a general linear regression model.
Results: Although positively correlated intrinsic co-activation was observed bilaterally in the frontal cortex in both HIV subjects and controls (p < 0.05, uncorrected), greater bilateral DLPFC and medial frontal gyrus representation was evident in HIV patients with the strongest correlations apparent in some DLPFC regions among controls. These results were observed for both DLPFC seeds. Increasing age was associated with reduced connectivity of the DLPFC bilaterally. Discussion: The greater spatial extent and reduced magnitude of bilateral intrinsic frontal correlations in the HIV subjects suggest a compensatory response to brain injury associated with HIV infection. Moreover, evidence of diminished frontal connectivity in older subjects may reflect deterioration of synaptic junctions in this region associated with old age. Additional results from between-group and multivariate analyses will be presented at the conference. Conclusion: This study provides preliminary evidence for a possible compensatory response to neurodegeneration in chronic HIV, as reflected by differences in intrinsic bilateral connectivity in the frontal cortex. |
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