Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Tricia King, Ph.D.

Second Advisor

Longchuan Li, Ph.D.

Third Advisor

Bruce Crosson, Ph.D.

Fourth Advisor

Vonetta Dotson, Ph.D.


Neuroimaging techniques have been used to investigate the neurobiological mechanisms of cognitive deficits in survivors of childhood brain tumors. Graph theory is a quantitative method that characterizes brains as a complex system. By modeling brain regions as ‘nodes’ and white matter tracts between each brain region pair as ‘edges,’ graph theory provides metrics that quantify the topological properties of networks. Given that brain tumor survivorship is associated with focal and diffuse impairments, a network analysis can provide complementary information to previous neuroimaging studies in this clinical group. This study used diffusion-weighted imaging and deterministic tractography to examine the properties of the structural networks in 38 adult survivors of pediatric brain tumors (Mean age=22.5, 55% female, mean years post diagnosis=14.1 (6.2), Range post diagnosis = 4.5-30 years). Results of this study suggest that long term survivorship is associated with altered structural networks with respect to measures of integration, segregation, and centrality. Further, properties of the network mediate differences in cognitive flexibility performance between survivors and healthy peers, and mediate the relationship between cumulative neurological risk and cognitive flexibility performance.