PL01.4.A The relationship between neuronal activity and functional network properties in glioma patients

Abstract

Abstract Background Glioma is associated with pathologically high neuronal activity around the tumor, which associates with faster tumor progression in patients. Concurrently, patients with glioma have local and widespread disturbances of the functional brain network as measured with magnetoencephalography (MEG) such as higher network clustering (the extent to which regions connected to a particular area are also connected to each other) and locally altered integrative connectivity (for instance assessed with a centrality measure). How local neuronal activity and nodal network properties relate to each other has yet to be investigated. Material and Methods We obtained eyes-closed resting-state MEG in 95 glioma patients before tumor resection and 57 matched healthy controls (HC). Broadband power (BBP, 0.5-48Hz) was used as a proxy for neuronal activity. The local clustering coefficient (CC) and eigenvector centrality (EC) were calculated for the functional network in the lower frequency bands (delta, theta, alpha). We compared averaged nodal network properties and local BBP between peritumoral (regions partially overlapping with the tumor) and contralateral homologue regions in patients and compared these to averaged values in HC. Linear mixed models were used to relate nodal CC and EC to local BBP. Results were corrected for multiple comparisons and deemed significant at alpha 0.05. Results The peritumoral area was significantly more active than the non-peritumoral homologue in patients, and showed pathologically higher activity in comparison to HCs. Pathologically high neuronal activity was restricted to the peritumoral areas and not found in the contralateral homologue. However, patients’ functional network was disturbed throughout the brain in terms of pathologically high clustering, but not with regards to centrality. Whereas high activity related to high centrality in HCs and patients alike, high activity seemed to relate to low clustering in homologue regions in patients but not HCs, potentially indicating that lower neuronal activity relates to pathologically high clustering in these patients. Conclusion Glioma patients show pathologically high brain activity around the tumor and whole-brain disturbances in local network clustering, while integrative connectivity is preserved. We also find that the relationship between neuronal activity and functional network properties is complex in these patients, further underlining the importance of investigating how local activity may impact global network topology in order to understand how neuron-glioma interactions shape brain functioning.