Date of Degree

6-2021

Document Type

Thesis

Degree Name

M.S.

Program

Cognitive Neuroscience

Advisor

Junghoon J Kim

Subject Categories

Cognitive Neuroscience

Keywords

DMN, TBI, functional connectivity, hyperconnectivity

Abstract

Traumatic brain injury (TBI) patients are known to have altered functional connectivity (FC), which has cognitive and behavioral significance and bears clinical implications. Previous literature has discovered a hyperconnectivity response to TBI, most notably in the default mode network (DMN). However, the exact pattern of changes in resting FC during the first year of recovery is unknown. We used resting-state functional magnetic resonance imaging to investigate longitudinal connectivity patterns in the DMN of 28 moderate-to-severe TBI patients as compared to 33 demographically matched healthy controls (HC). FC was assessed at 3, 6, and 12 months post-injury for patients using the posterior cingulate cortex (PCC) as the seed. The first aim of this study was to investigate the resting state FC response in the DMN in the TBI group compared to HC. The second aim involved the evolution of FC responses throughout the first year of recovery from neurotrauma in the patient group. We found in our cross-sectional analysis that patients showed hyperconnectivity responses in the right middle temporal lobe at 3 months post-injury, and hypoconnectivity in the left lateral occipital lobe at 12 months post-injury. However, when we conducted our longitudinal analysis and compared FC across the time points directly with each other, no areas showed a significant change within the TBI group. Our findings suggest a dynamic nature of FC alteration over the first year of recovery after TBI, by showing a hyperconnectivity in the subacute phase and a hypoconnectivity in posterior brain regions as patients reach a more chronic stage. The pattern of FC changes should be further extrapolated into cognitive and behavioral implications, as well as translated into mechanisms of recovery.

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