NeuroImage
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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. ⋯ 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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The aim of this study was to compare the relative effectiveness of 6 different commonly used language fMRI activation paradigms, including receptive and expressive, as well as semantic and phonological tasks, for hemispheric lateralization in brain tumor patients utilizing both threshold-dependent and threshold-independent approaches. We studied 46 right-handed patients with primary intra-axial brain tumors with BOLD fMRI on a 3-T MRI system. A linear fit of the laterality indices (LIs) as a function of the t-value (which varied from 2.0 to 6.5) was calculated and the slope (M) taken as measure of LI variability in the threshold-dependent LI approach; for the threshold-independent approach, the LIs were determined by comparing the integrated T-score weighted distributions of all positively task-correlated voxels of the left and the right hemispheric regions of interest. ⋯ Furthermore, R (mean LI value=61.91, M=7.9±1.5) had a higher mean LI value and was less threshold-dependent than SWG (mean LI=52.97, M=11.40±0.64) for LI determination. SWG and R were able to provide effective language lateralization even in the subgroup of patients with lesions located in the left hemisphere and in the frontal or parietal lobes. The receptive language paradigms examined in this study (passive listening [PL], listening comprehension [LC], and reading comprehension [RC]) were less effective than SWG and R for language lateralization.
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Blast-induced traumatic brain injury (bTBI) is the "signature wound" of the current wars in Iraq and Afghanistan. However, with no objective information of relative blast exposure, warfighters with bTBI may not receive appropriate medical care and are at risk of being returned to the battlefield. Accordingly, we have created a colorimetric blast injury dosimeter (BID) that exploits material failure of photonic crystals to detect blast exposure. ⋯ Although very stable in the presence of heat, cold or physical impact, sculpted micro- and nano-structures of the BID are physically altered in a precise manner by blast exposure, resulting in color changes that correspond with blast intensity. This approach offers a lightweight, power-free sensor that can be readily interpreted by the naked eye. Importantly, with future refinement this technology may be deployed to identify soldiers exposed to blast at levels suggested to be supra-threshold for non-impact blast-induced mild TBI.
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The objective of the study was to examine whether deep brain stimulation (DBS) of the subthalamic nucleus (STN), the globus pallidus internus (GPi), and/or the ventralis intermedius thalamic nucleus (Vim) was associated with making patients angrier pre to post-surgical intervention. ⋯ STN and GPi DBS for Parkinson's disease were associated with significantly higher anger scores pre- to post-DBS as compared to Vim for essential tremor. Anger score changes in STN and GPi patients seem to be associated with microelectrode passes, suggesting that it may be a lesional effect. PD patients with longer disease duration may be particularly susceptible, and this should be kept in mind when discussing the potential of DBS surgery for an individual patient. Essential tremor patients who on average have much longer disease durations did not get angrier. The changes in anger scores were not related to LED change or dopamine agonist use. Whether the induction of anger is disease-specific or target-specific is not currently known; however, our data would suggest that PD patients implanted in STN or GPi are at a potential risk. Finally, on closer inspection of the COMPARE DBS data, VAMS anger scores did not change on or off DBS, suggesting that anger changes may be more of a lesional effect rather than a stimulation induced one (Okun et al., 2009).
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Resting state fluctuations in blood oxygenation level dependent functional connectivity magnetic resonance imaging (BOLD fcMRI) time-series have been increasingly employed to study functional connectivity networks in healthy and diseased brain. FcMRI studies have been conducted under a number of different conditions, including resting eyes open, visual fixation and finger tapping. ⋯ In this study, state-dependence of functional connectivity to dorsal and ventral striatum was assessed with fcMRI during an eyes open resting state condition (REST) and during continuous 3 Hz transcutaneous electrical nerve stimulation (TENS), with the a priori hypotheses: (1) dorsal striatum connectivity with sensorimotor/attention networks will be stronger during TENS compared to REST, (2) ventral striatum connectivity with limbic system emotion-processing network will be weaker during TENS compared to REST and (3) ventral striatum connectivity with sensorimotor/attention networks will be stronger during TENS compared to REST. These hypotheses were confirmed by the results obtained, indicating that resting state BOLD fMRI networks reflect, in substantial measure, state-dependent activity.