Functional connectivity within posterolateral parietal cortex and its alteration in traumatic brain injury
Open Access
- Author:
- Venkatesan, Umesh Meyyappan
- Graduate Program:
- Psychology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- July 18, 2017
- Committee Members:
- Frank Gerard Hillary, Dissertation Advisor/Co-Advisor
Frank Gerard Hillary, Committee Chair/Co-Chair
Nancy Anne Coulter Dennis, Committee Member
Stephen Jeffrey Wilson, Committee Member
Charles Geier, Outside Member - Keywords:
- traumatic brain injury
fmri
functional connectivity
resting state
graph theory
neuroplasticity
parietal
default mode
neuropsychology
TBI
frontoparietal - Abstract:
- Spatially distributed functional brain networks show multiple points of regional convergence (“hubs”), suggesting that local network architecture supports global systems communication. Traumatic brain injury (TBI) alters global connectivity patterns, but relatively little is known about its effect on interactions within local hub environments and whether this has implications for cognition. The goal of the dissertation was to examine one such environment, the posterolateral parietal cortex (PPC), in relation to distributed network connectivity and cognition in both TBI (n=18) and healthy controls (n=19). Using resting-state functional MRI in conjunction with seed-voxel and graph theoretical connectivity analyses, the study revealed evidence for increased connectivity, or hyperconnectivity, in TBI from portions of left and right PPC to right-lateralized default mode and frontoparietal control network regions, as well as within the local right PPC network itself. Across groups, right versus left PPC showed increased local connection strength and decreased betweenness centrality, a measure of network hubness. In TBI, strength and global efficiency within the right PPC were strongly negatively correlated with auditory attention span and attentional reaction time, respectively. Overall, these findings substantiate hyperconnectivity on both global and local levels after TBI. Importantly, they propose a special role for local network communication within the right hemisphere in facilitating large-scale information transfer after neurologic insult. Local network organization in TBI also appears to have consequences for cognitive functioning, potentially reflecting a need to balance functional resource demand with network efficiency.