Alterations in the Magnetoencephalography Default Mode Effective Connectivity following Concussion

Abstract

BACKGROUND AND PURPOSE: Magnetoencephalography is sensitive to functional connectivity changes associated with concussion. However, the directional influences between functionally related regions remain unexplored. In this study, we therefore evaluated concussion-related magnetoencephalography-based effective connectivity changes within resting-state default mode network regions. MATERIALS AND METHODS:Resting-state magnetoencephalography was acquired for 8 high school football players with concussion at 3 time points (preseason, postconcussion, postseason), as well as 8 high school football players without concussion and 8 age-matched controls at 2 time points (preseason, postseason). Time-series from the default mode network regions were extracted, and effective connectivity between them was computed for 5 different frequency bands. The default mode network regions were grouped into anterior and posterior default mode networks. The combined posterior-to-anterior and anterior-to-posterior effective connectivity values were averaged to generate 2 sets of values for each subject. The effective connectivity values were compared using a repeated measures ANOVA across time points for the concussed, nonconcussed, and control groups, separately.RESULTS: A significant increase in posterior-to-anterior effective connectivity from preseason to postconcussion (corrected P value ¼ .013) and a significant decrease in posterior-to-anterior effective connectivity from postconcussion to postseason (corrected P value ¼ .028) were observed in the concussed group. Changes in effective connectivity were only significant within the delta band. Anterior-to-posterior connectivity demonstrated no significant change. Effective connectivity in the nonconcussed group and controls did not show significant differences.

Resting-state causal brain connectivity in youth female athletes suggest sex-related differences following subacute concussion

“…Participants with subacute concussion showed symmetrical bilateral patterns with reduced central-parietal activity and additional frontal-temporal connections. Another study found increased posteriorto-anterior effective connectivity following concussion in sample of male high school football players (34). In a pediatric case-control sample, post-concussion effective connectivity within the DMN showed increased inter-and intra-hemispheric anterior connectivity, with unique connections from the orbitofrontal cortex to parietal regions (35).…”

“…A limited number of causal connectivity analyses have been employed in concussed populations (33)(34)(35)(36)(37). We previously investigated causal connectivity in a sample of adolescent male hockey players, finding significant differences between those with subacute concussion and healthy controls (33).…”

“…Increased connectivity was observed from the left anterior cingulate cortex to areas of the frontal lobe and the left insula, as well as from the right insula to the left superior temporal gyrus (36,37). Hristopulos et al (33) and Reddy et al (34) included only male participants. Vaughn et al (35) and Li et al (36,37) included both males and females, but did so in pediatric and adult populations.…”

Contextual Effects of Traumatic Brain Injury on the Connectome: Differential Effects of Deployment- and Non–Deployment-Acquired Injuries

“…Several studies have found increased levels of connectivity deemed “hyperconnectivity.”28 Magnetoencephalography (MEG) has been utilized to demonstrate support of the hyperconnectivity hypothesis in mild TBI, reporting increased connection strength in several frequency ranges in the DMN29,30 as well as the rich club 31. Other studies have found decreased levels of connectivity associated with mild TBI or mixed results based on the region examined 32–34…”

“…31 Other studies have found decreased levels of connectivity associated with mild TBI or mixed results based on the region examined. [32][33][34] Results describing the effect of TBI on the strength of connectivity and the organization and topology of the functional connectome are mixed. This is potentially a result of studies varying by sample population (eg, civilian, veteran, mixed severities), time since injury, methods utilized, and the technology employed.…”