Graph theory analysis of functional and structural connectome: Links to Auditory Processing Disorder

Abstract

The aim of this thesis was to provide insight into the functional and structural organisations in school-aged children with and without a clinical diagnosis of auditory processing disorder (APD) using the network neuroscience approach and neuroimaging techniques such as functional magnetic resonance imaging (MRI) and diffusion MRI. The first study investigated the functional connection, the whole-brain functional network properties and hub architecture in 57 children aged 8-14 years diagnosed with APD (N = 28) and a healthy control (HC) group without hearing difficulties (N = 29). The second study examined the structural connection and rich-club organisation in children with APD (N = 29) and HCs (N = 29) from the same cohort. In both studies, we also explored the brain-behaviour relationship between network measures that showed between-group differences and performance on the listening-in-spatialised-noise-sentences (LiSN-S) task. The first study showed similarities in functional connectivity, global network properties and modular organisation in children with APD and HCs. However, at the regional level, the APD group demonstrated a decrease in participation coefficient (PC) in the bilateral superior temporal gyrus within the default mode network (DMN). The second study revealed similar rich-club organisation and structural connection in the APD group compared with HCs. At the nodal level, we detected an increase in regional connectivity within DMN and executive control network in the APD group. The regions identified in Study 2 showing group differences were the right inferior parietal lobule and inferior precentral gyrus based on network measures of average path length (APL) and betweenness centrality, respectively. In Study 1, the APD group showed a positive correlation in the left parahippocampal gyrus between PC and Spatial advantage performance on the LiSN-S task. In contrast, in Study 2, only the HC group showed a positive association between APL in the left orbital gyrus and Spatial advantage score. Our findings from both studies provided evidence of altered regional brain network organisation in APD and suggested that these alterations exist within the structure-function networks. Together, the work presented in this thesis indicates the involvement of multimodal changes in brain connectivity underlying the listening difficulties of children with APD.