Date of Award

5-31-2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering - (Ph.D.)

Department

Electrical and Computer Engineering

First Advisor

Xiaobo Li

Second Advisor

Durgamadhab Misra

Third Advisor

Abdallah Khreishah

Fourth Advisor

Xuan Liu

Fifth Advisor

Tara L. Alvarez

Sixth Advisor

Yun Q. Shi

Abstract

Traumatic Brain Injury (TBI) is one of the major public health concerns with approximately 70 million new cases occurring worldwide per year. It is often caused by a forceful bump, blow, or jolt to the head, resulting in brain tissue damage and normal brain functions disruption. All grades of TBI, ranging from mild to severe, can cause wide-ranging and long-term effects on affected individuals, resulting in physical impairments, and neurocognitive consequences that permanently affect their abilities to perform daily activities. Attention deficits are the most common persisting neurocognitive consequences following TBI, which significantly contribute to poor academic and social functioning, and life-long learning difficulties of affected individuals. However, attention deficits have been evaluated and treated based on symptom endorsements from subjective observations, with few therapeutic interventions successfully translated to the clinic. The consensus regarding appropriate evaluation and treatment of TBI induced attention deficits in this cohort is rather limited due to the lack of investigations of the neurobiological substrates associated with this syndrome.

The overall aim of this dissertation research is to systematically investigate the neurobiological mechanisms associated with attention deficits in adults post TBI by utilizing multiple powerful neuroimaging techniques including the functional near-infrared spectroscopy (fNIRS) and multimodal magnetic resonance imaging (MRI), with an ultimate goal of translating hypothesis-driven neurobiological correlates into the quantitatively measurable biomarkers for diagnosis of TBI-induced attention deficits and development of more refined long-term treatment and intervention strategies.

This dissertation research is conducted through three specific projects. Project 1 focuses on the investigation of brain functional patterns including the regional cortical brain activation and between-regional pairwise functional connectivity responding to visual sustained attention processing in individuals with and without TBI, by utilizing the fNIRS technique. Project 2 continues the examination of brain functional patterns by assessing the whole brain network topological properties responding to visual sustained attention processing in a larger sample of individuals with and without TBI, by utilizing the functional MRI technique and a graph theoretic approach. Project 3, on the other hand, investigates the brain structural characteristics based on the same sample involved in Project 2, by utilizing the structural MRI and diffusion tensor imaging techniques. For all these three projects, the differences of these brain imaging measures are compared between the groups of TBI and control. Correlation analyses are further conducted between those brain imaging measures which shows significant between-group differences and attention-related behaviors. In addition, Project 3 additionally investigates gender-specific patterns of the altered brain structural properties in TBI patients, relative to controls.

The outcome of this novel and valuable dissertation research may shed light on the neural mechanisms of attention deficits in adults post TBI, and may suggest the neurobiological targets for treatment of this severe and common condition. It may also provide important neural foundation for future research to develop effective rehabilitation strategies to improve attention processing in adults post TBI.

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