Abnormal connectivity in the sensorimotor network predicts attention deficits in traumatic brain injury

Elena Shumskaya,David G Norris,Roy P C Kessels,Pieter E Vos,Marcel A J Van Gerven

doi:10.1007/s00221-016-4841-z

Abstract

The aim of this study was to explore modifications of functional connectivity in multiple resting-state networks (RSNs) after moderate to severe traumatic brain injury (TBI) and evaluate the relationship between functional connectivity patterns and cognitive abnormalities. Forty-three moderate/severe TBI patients and 34 healthy controls (HC) underwent resting-state fMRI. Group ICA was applied to identify RSNs. Between-subject analysis was performed using dual regression. Multiple linear regressions were used to investigate the relationship between abnormal connectivity strength and neuropsychological outcome. Forty (93%) TBI patients showed moderate disability, while 2 (5%) and 1 (2%) upper severe disability and low good recovery, respectively. TBI patients performed worse than HC on the domains attention and language. We found increased connectivity in sensorimotor, visual, default mode (DMN), executive, and cerebellar RSNs after TBI. We demonstrated an effect of connectivity in the sensorimotor RSN on attention (p < 10−3) and a trend towards a significant effect of the DMN connectivity on attention (p = 0.058). A group-by-network interaction on attention was found in the sensorimotor network (p = 0.002). In TBI, attention was positively related to abnormal connectivity within the sensorimotor RSN, while in HC this relation was negative. Our results show altered patterns of functional connectivity after TBI. Attention impairments in TBI were associated with increased connectivity in the sensorimotor network. Further research is needed to test whether attention in TBI patients is directly affected by changes in functional connectivity in the sensorimotor network or whether the effect is actually driven by changes in the DMN.

Highlights

Traumatic brain injury (TBI) is a major cause of mortality and morbidity
We report stronger functional connectivity (FC) during resting state in chronic moderate/severe TBI patients in a number of resting-state networks (RSNs): sensorimotor, default-mode network (DMN), visual, executive control, and cerebellar RSNs
A stronger function coupling within these networks may underlie behavioural impairments and symptoms observed in TBI and/ or be indicative of compensation mechanisms, leading to recovery of impaired cognitive functions

Summary

Introduction

Traumatic brain injury (TBI) is a major cause of mortality and morbidity. In Europe, TBI accounts for the greatest number of total years lived with disability resulting from trauma, and it is among the top three causes of injury-related medical costs to society (Maas et al 2008). Interactions between spatially distinct brain regions become compromised, disrupting cognitive processing (Sharp et al 2014). This disruption can be studied by two neuroimaging approaches. Alterations in functional connectivity (FC) can be studied by resting-state fMRI. The brain shows spontaneous low-frequency neuronal fluctuations that are synchronized over spatially distributed networks, even in the absence of a specific task. These fluctuations can be measured as the blood oxygen level-dependent (BOLD) response during rest with fMRI (Biswal et al 1995). Several resting-state networks (RSNs) have been identified that can be linked to higher-order cognitive processing using rs-fMRI, including the default-mode network (DMN), sensorimotor network, posterior visual processing network, and dorsal attention network (Damoiseaux et al 2006; Lee et al 2012)

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