Complexity Analysis of Resting State Magnetoencephalography Activity in Traumatic Brain Injury Patients

Abstract

Diagnosis of mild traumatic brain injuries (TBIs) has been difficult because of the absence of obvious focal brain lesions, using conventional computed tomography (CT) or magnetic resonance imaging (MRI) scans, in a large percentage of TBIs. One useful measure that can characterize potential tissue and neural network damage objectively is Lempel-Ziv complexity (LZC) applied to magnetoencephalography (MEG) signals. LZC is a model-independent estimator of system complexity that estimates the number of different patterns in a sequence. We hypothesized that because of the potential network damage, TBIs would show a reduced level of complexity in regions that are impaired. We included 18 healthy controls and 18 military veterans with TBI in the study. Resting state MEG data were acquired, and the LZCs were analyzed across the whole brain. Our results indicated reduced complexity in multiple brain areas in TBI patients relative to the healthy controls. In addition, we detected several neuropsychological measures associated with motor responses, visual perception, and memory, correlated with LZC, which likely explains some of the cognitive deficits in TBI patients.

Altered cross-frequency coupling in resting-state MEG after mild traumatic brain injury

“…The current study was successful in analyzing resting-state MEG activity alone (Luo et al, 2013, Zouridakis et al, 2012Dimitriadis et al, 2015b;Li et al, 2015) revealing the side of the FCG for which the control group presented significantly different efficiency than the mTBI group (Figures 2 and 3).…”

“…Consequently, during the past several years, numerous studies have attempted to develop reliable biomarkers of mTBI based on MEG (see reviews by Jeter et al, 2013, and Huang et al, 2009. Of particular interest is the analysis of resting-state MEG activity either alone (Luo et al, 2013, Zouridakis et al, 2012Dimitriadis et al, 2015a;Li et al, 2015) or combined with diffusion tensor imaging (DTI) MRI (Huang et al, 2014).…”

Increased Network Excitability Due to Altered Synaptic Inputs to Neocortical Layer V Intact and Axotomized Pyramidal Neurons after Mild Traumatic Brain Injury

“…[16][17][18] These structural findings have also been confirmed by functional magnetic resonance imaging (MRI) and resting state MRI and magnetoencephalography (MEG) that implicates DAI with subsequent circuit disruption and disorders of brain connectivity following mTBI. [19][20][21][22] In addition to these structural changes in axonal connectivity, axonal stretch and ionic imbalances after injury likely induce additional changes not immediately obvious in structural studies. 15 In fact, recent studies have begun to posit that mTBIs can involve primary electrophysiological change related to an …”

Evaluation of Cortical Thickness after Traumatic Brain Injury in Military Veterans

“…[27][28][29][30] Performance on neuropsychological measures in these domains has also been linked to differences in neural activity in veterans with mild TBI as measured by magnetoencephalography (MEG). 16,31,32 These changes are thought to result from disruptions in the integrity of neural networks in both cortical and subcortical areas. 32 Thus far, cortical thinning has been shown to correlate with performance on measures of verbal memory and visuomotor speed, which are common cognitive domains affected in individuals with TBI.…”