Dissertations, Theses, and Capstone Projects

Date of Degree

2-2025

Document Type

Thesis

Degree Name

M.S.

Program

Cognitive Neuroscience

Advisor

Junghoon Kim

Subject Categories

Cognitive Neuroscience | Computational Neuroscience | Neurosciences | Other Neuroscience and Neurobiology

Keywords

Traumatic Brain Injury, Neurovascular Coupling, Cerebral Blood Flow, Resting-State fMRI Fluctuations, Magnetic Resonance Imaging, Post-Traumatic Amnesia

Abstract

Traumatic brain injury (TBI) is known to involve damage in the neurovascular unit. TBI may disrupt the brain’s neurovascular coupling–the relationship between cerebral blood flow and neural activity–that can lead to cognitive and functional impairments. This study attempted to non-invasively investigate neurovascular coupling in patients with moderate to severe TBI (msTBI) during the first year post-injury using a combined metric of cerebral blood flow (CBF) and fractional amplitude of low-frequency fluctuations (fALFF), a proxy for spontaneous neural activity. Using arterial spin labeling (ASL) and functional MRI sequences, CBF and fALFF were measured in 29 msTBI patients 3-, 6- and 12-months post-injury for within-group longitudinal comparisons. Thirty-four demographically matched healthy controls were assessed once for between-group comparisons. A vertex-based preprocessing pipeline was used to map spatial patterns of CBF-fALFF coupling across the cortical surface. Across-vertex global coupling was estimated by association (measured by regression or correlation coefficients) between CBF and fALFF values across the whole hemisphere. In addition, vertex-wise regional coupling values were calculated using locally weighted regression between fALFF and CBF. The coupling calculated on a global level revealed significant group differences between controls and TBI patients, indicating potential neurovascular coupling dysfunction in chronic msTBI patients. At 6 months post-injury, the duration of post-traumatic amnesia was significantly correlated with global coupling values based on regression coefficients. In contrast, after correcting for multiple comparisons, the vertex-wise regional group comparison showed no significant differences in CBF-fALFF coupling between msTBI patients and controls. Neither globally nor locally defined coupling metrics showed significant longitudinal changes or relationships with neuropsychological variables within the patient group. Potential explanations underlying the absence of longitudinal differences and the dissociation between the global and local coupling findings were discussed.

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