Physical activity and frontoparietal network connectivity in traumatic brain injury

Abstract

Background: Prolonged changes to functional network connectivity as a result of a traumatic brain injury (TBI) may relate to long-term cognitive complaints reported by TBI survivors. No interventions have proven to be effective at treating long-term cognitive complaints after TBI but physical activity has been shown to promote cognitive function and modulate functional network connectivity in non-injured adults. Therefore, the objective of this study was to test if physical activity engagement was associated with functional connectivity of the cognitively relevant frontoparietal control network (FPCN) in adults with a TBI history.

Methods: In a case-control study design, resting state function magnetic resonance imaging and physical activity data from a subset of participants (18-81 years old) from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) study was analyzed. Fifty-seven participants reported a prior head injury with loss of consciousness and 57 age and sex matched controls were selected. Seed-based functional connectivity analyses were performed using seeds in the dorsolateral prefrontal cortex and the inferior parietal lobule, to test for differences in functional connectivity between groups, associations between physical activity and functional connectivity within TBI as well as differential associations between physical activity and functional connectivity between TBI and controls.

Results: Seed-based connectivity analyses from the dorsolateral prefrontal cortex showed that those with a history of TBI had decreased positive connectivity between dorsolateral prefrontal cortex and intracalcarine cortex, lingual gyrus, and cerebellum, and increased positive connectivity between dorsolateral prefrontal cortex and cingulate gyrus and frontal pole in the TBI group. Results showed that higher physical activity was positively associated with increased connectivity between the dorsolateral prefrontal cortex and inferior temporal gyrus. Differential associations were observed between groups whereby the strength of the physical activity-functional connectivity association was different between the inferior parietal lobule and inferior temporal gyrus in TBI compared to controls.

Discussion: Individuals with a history of TBI show functional connectivity alterations of the FPCN. Moreover, engagement in physical activity is associated with functional network connectivity of the FPCN in those with a TBI. These findings are consistent with the evidence that physical activity affects FPCN connectivity in non-injured adults; however, this effect presents differently in those with a history of TBI.

Keywords: frontoparietal control network; physical activity; traumatic brain injury.

FIGURE 1

Regions of Interest for seed‐based correlations (SBC) analysis in frontal parietal control network, calculated by overlaying Schaefer atlas overtop Harvard Oxford Atlas anatomical space. (a) Inferior parietal lobe and (b) dorsolateral prefrontal cortex.

FIGURE 2

Resting state seed‐based connectivity (rsFC) in the dorsolateral prefrontal cortex (dlpfc) between traumatic brain injury (TBI) and no TBI. Violin plots are demonstrating the connectivity strength between dorsolateral prefrontal cortex and four resulting clusters in both groups and the transparent threshold map of connectivity correlations (r = −.1–.1) for this analysis with the significant clusters outlined in black. (a) Cluster within the intracalcarine cortex with lower connectivity in the TBI group. (b) Cluster spanning the cerebellum with lower connectivity in the TBI group. (c) Cluster within the frontal pole higher connectivity in the TBI group. (d) Cluster within cingulate gyrus with higher connectivity in the TBI group.

FIGURE 3

Plot showing effect sizes of each bilateral seed of the dorsolateral prefrontal cortex (DLPFC) and its associated cluster. Negative effect sizes indicate hypoconnectivity and positive effect sizes indicate hyperconnectivity.

FIGURE 4

Seed‐based connectivity with associations between physical activity and functional connectivity in traumatic brain injury (TBI) group. (a,b) Higher physical activity (PAEE) was significantly and positively associated with functional connectivity between both the L and R dorsolateral prefrontal cortex (DLPFC) and a cluster in the R inferior temporal gyrus (ITG). (c) Unthresheld map of connectivity correlations. Significant cluster outlined in black. (d) Effect size plot demonstrating the effect sizes of each bilateral seed.

FIGURE 5

No traumatic brain injury (TBI) and TBI differences in physical activity (a) violin plot showing physical activity in each group. (b) Seed‐based connectivity results from the L and R inferior parietal lobule (IPL) showing the differential relationship between physical activity (PAEE) and TBI and controls in a cluster in the R inferior temporal gyrus (ITG). (c) Thresholded (r = .01) map of connectivity correlation strength with statistically significant cluster outlined in black. (d) interaction plot depicting the differential association between physical activity and functional connectivity in TBI (purple) compared to controls (blue). (e) Effect size plot demonstrating the effect sizes of each bilateral seed for each group.