title: Connectivity in MEG resting-state networks increases after resective surgery for low-grade glioma and correlates with improved cognitive performance.
abstract: OBJECTIVE
  Low-grade glioma (LGG) patients often have cognitive deficits. Several disease- and treatment related factors affect cognitive processing. Cognitive outcome of resective surgery is unpredictable, both for improvement and deterioration, especially for complex domains such as attention and executive functioning. MEG analysis of resting-state networks (RSNs) is a good candidate for presurgical prediction of cognitive outcome. In this study, we explore the relation between alterations in connectivity of RSNs and changes in cognitive processing after resective surgery, as a stepping stone to ultimately predict postsurgical cognitive outcome.
  
  
  METHODS
  Ten patients with LGG were included, who had no adjuvant therapy. MEG recording and neuropsychological assessment were obtained before and after resective surgery. MEG data were recorded during a no-task eyes-closed condition, and projected to the anatomical space of the AAL atlas. Alterations in functional connectivity, as characterized by the phase lag index (PLI), within the default mode network (DMN), executive control network (ECN), and left- and right-sided frontoparietal networks (FPN) were compared to cognitive changes.
  
  
  RESULTS
  Lower alpha band DMN connectivity was increased after surgery, and this increase was related to improved verbal memory functioning. Similarly, right FPN connectivity was increased after resection in the upper alpha band, which correlated with improved attention, working memory and executive functioning.
  
  
  CONCLUSIONS
  Increased alpha band RSN functional connectivity in MEG recordings correlates with improved cognitive outcome after resective surgery. The mechanisms resulting in functional connectivity alterations after resection remain to be elucidated. Importantly, our findings indicate that connectivity of MEG RSNs may be used for presurgical prediction of cognitive outcome in future studies.
authors.affiliation: Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: van Dellen
authors.forename: P C
authors.initials: PC
authors.lastname: de Witt Hamer
authors.forename: L
authors.initials: L
authors.lastname: Douw
authors.forename: M
authors.initials: M
authors.lastname: Klein
authors.forename: J J
authors.initials: JJ
authors.lastname: Heimans
authors.forename: C J
authors.initials: CJ
authors.lastname: Stam
authors.forename: J C
authors.initials: JC
authors.lastname: Reijneveld
authors.forename: A
authors.initials: A
authors.lastname: Hillebrand
keywords: Cognition; Functional connectivity; Glioma; Magnetoencephalography; Resective surgery; Resting-state networks