Reduced brain connectivity and mental flexibility in mild traumatic brain injury

Abstract

Objective: A mild traumatic brain injury (mTBI), or concussion, has known neuropsychological sequelae, and neuroimaging shows disturbed brain connectivity during the resting state. We hypothesized that task-based functional connectivity measures, using magnetoencephalography (MEG), would better link the neurobiological underpinnings of cognitive deficits to specific brain damage.

Methods: We used a mental flexibility task in the MEG and compared brain connectivity between adults with and without mTBI.

Results: Affected individuals showed significant reductions in connectivity. When challenged with a more difficult task, these individuals were not able to "boost" their connectivity, and as such, showed deterioration in performance.

Interpretation: We discuss these findings in the context of limitations in cognitive reserve as a consequence of a mTBI.

Figure 1

Mean and standard deviations for (A) reaction time and (B) accuracy for each group and condition.

Figure 2

(A) Plots of whole‐brain connectivity changes over time in each frequency band, for the easy (intra‐) and hard (extradimensional) conditions, in the control and mild traumatic brain injury (mTBI) groups. The red bars indicate time windows where significant differences are seen between groups. (B) Adjacency matrices for the two time windows in the extradimensional condition for the two groups. Clear connections are seen in the left and right occipital regions with most other regions in both ipsilateral and contralateral cortex in the controls, but not in the mTBI group. (C) For the two time windows in the extradimensional condition, plots of connectivity strength are shown for the control and mTBI groups.