Investigation of Functional Changes of Brain Topology in Insomnia Disorder

IntroductionSleep is a complex maintaining homeostasis process; lack of sleep disrupts whole-body functioning(۱). Studies have shown brain networks have many special topological properties. Graph theory analysis can be adopted to investigate the functional changes at global and nodal levels. In graph theory, the brain network is defined as a set of nodes (denoting anatomical regions) and interconnecting edges (denoting functional or structural connections)(۲). This study investigates the functional changes of brain topology in insomnia disorder(ID) and compares the global and local characteristics with a healthy group.MethodThe rsfMRI and graph theory analysis method was applied to investigate the brain functional connectome patterns among ۵۶ patients and ۵۲ control subjects (۲۰-۶۰ years old). Participants were scanned with a ۱.۵tesla Magnetom-Avanto-Siemens scanner with an ۸-channel head coil. We used CONN toolbox(۳) with Harvard-Oxford atlas, The topologic properties of brain functional connectomes were tested. Global efficiency(GE) and local efficiency(LE) are the measures of network efficiency in transmitting information at the local and global levels (۱, ۲).ResultsThe brain regions with statistically-significant for Control>Patient one-sided(Negative) in the ID patients, showed decreased GE in the left postcentral gyrus and increased GE in vermis (p<.۰۵, p-FDR corrected)(Table ۱, Figure۱). We also saw statistically significant differences in LE.ConclusionsThe present study investigated topological brain functional connectome in ID. These patients showed altered GE in brain regions mainly implicated in the vermis and postcentral gyrus; vermis is intimately associated with all regions of the cerebellar cortex, having distinct connections with the brain. These regions are the vestibulocerebellum, which is responsible primarily for eye movements controlling and the postcentral gyrus is the primary somatosensory cortex and receives the majority of the somatic sensory relay information from the thalamus. Damage to the postcentral gyrus may result in contralateral somatosensory disturbances, primarily in tactile localization and discrimination and postural sensitivity(۴).