Article

Evidence of disrupted functional connectivity in the brain after combat-related blast injury

Veterans Affairs Medical Center, Minneapolis, MN 55417, USA.
NeuroImage (Impact Factor: 6.36). 01/2011; 54 Suppl 1:S21-9. DOI: 10.1016/j.neuroimage.2010.09.007
Source: PubMed

ABSTRACT Non-impact blast-related mild traumatic brain injury (mTBI) appears to be present in soldiers returning from deployments to Afghanistan and Iraq. Although mTBI typically results in cognitive deficits that last less than a month, there is evidence that disrupted coordination of brain activity can persist for at least several months following injury (Thatcher et al., 1989, 2001). In the present study we examined whether neural communication may be affected in soldiers months after blast-related mTBI, and whether coordination of neural function is associated with underlying white matter integrity. The investigation included an application of a new time-frequency based method for measuring electroencephalogram (EEG) phase synchronization (Aviyente et al., 2010) as well as fractional anisotropy measures of axonal tracts derived from diffusion tensor imaging (DTI). Nine soldiers who incurred a blast-related mTBI during deployments to Afghanistan or Iraq were compared with eight demographically similar control subjects. Despite an absence of cognitive deficits, the blast-related mTBI group exhibited diminished EEG phase synchrony of lateral frontal sites with contralateral frontal brain regions suggesting diminished interhemispheric coordination of brain activity as a result of blast injury. For blast injured (i.e., blast-related mTBI) soldiers we found that EEG phase synchrony was associated with the structural integrity of white matter tracts of the frontal lobe (left anterior thalamic radiations and the forceps minor including the anterior corpus callosum). Analyses revealed that diminished EEG phase synchrony was not the consequence of combat-stress symptoms (e.g., post-traumatic stress and depression) and commonly prescribed medications. Results provide evidence for poor coordination of frontal neural function after blast injury that may be the consequence of damaged anterior white matter tracts.

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    • "Cook et al. (2009) reported that, when compared to control subjects, adults with childhood trauma had significantly higher EEG coherence in the alpha and beta frequency bands over the left temporo-parietal areas and in the right central and temporal areas, respectively. Sponheim et al. (2011), in a sample of soldiers with mild traumatic brain injury, detected that PTSD patients had higher frontal functional connectivity, especially in low frequency bands (delta, theta, alpha, beta1), than those without PTSD. Moreover, in a recent network analysis study, Lee et al. (2014) observed that, compared to control subjects, PTSD patients had lower strength and efficacy connections between frontal and central areas, particularly in beta and gamma frequency bands. "
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