ABSTRACT
Primary objective: Alterations to functional connectivity following a traumatic brain injury (TBI) may lead to impaired cognitive performance and major depressive disorder (MDD). In particular, functional gamma band connectivity is thought to reflect information binding important for working memory. The objective of this study was to determine whether altered functional gamma connectivity may be a factor in MDD following TBI (TBI-MDD).
Research design: This study assessed individuals with TBI-MDD, as well as individuals with TBI alone and MDD alone using electroencephalographic recordings while participants performed a working memory task to assess differences in functional connectivity between these groups.
Methods and procedures: Functional connectivity was compared using the debiased weighted phase lag index (wPLI). wPLI was measured from a group of healthy controls (n = 31), participants with MDD (n = 17), participants with TBI (n = 20) and participants with TBI-MDD (n = 15).
Main outcomes and results: Contrary to the predictions, this study found both the groups with TBI and TBI-MDD showed higher gamma connectivity from posterior regions during WM retention.
Conclusions: This may reflect dysfunctional functional connectivity in these groups, as a result of maladaptive neuroplastic reorganization.
Declaration of interest
Funding for this study was provided by Monash University and the Victorian Neurotrauma Initiative. Equipment funding was provided in part by the Neurosciences Victoria Clinical Neurobiology of Psychiatry Platform. PBF is supported by a Practitioner Fellowship grant from the National Health and Medical Research Council (NHMRC). RAS and NCR are supported by Early Career Fellowships from NHMRC. KEH and JJM are supported by Career Development Fellowships from the NHMRC.
PBF has received equipment for research from Medtronic Ltd, Magventure A/S and Brainsway Ltd and funding for research from Cervel Neurotech. NWB, RAS, KEH, JJM, NCR and CMS report no conflicts of interest.