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Deficits in Visual System Functional Connectivity after Blast-Related Mild TBI are Associated with Injury Severity and Executive Dysfunction
Journal article   Open access   Peer reviewed

Deficits in Visual System Functional Connectivity after Blast-Related Mild TBI are Associated with Injury Severity and Executive Dysfunction

Casey S Gilmore, Jazmin Camchong, Nicholas D Davenport, Nathaniel W Nelson, Randy H Kardon, Kelvin O Lim and Scott R Sponheim
Brain and behavior, Vol.6(5), pp.e00454-n/a
05/2016
DOI: 10.1002/brb3.454
PMCID: PMC4873652
PMID: 27257516
url
https://doi.org/10.1002/brb3.454View
Published (Version of record) Open Access

Abstract

Approximately, 275,000 American service members deployed to Iraq or Afghanistan have sustained a mild traumatic brain injury (mTBI), with 75% of these incidents involving an explosive blast. Visual processing problems and cognitive dysfunction are common complaints following blast-related mTBI. In 127 veterans, we examined resting fMRI functional connectivity (FC) of four key nodes within the visual system: lateral geniculate nucleus (LGN), primary visual cortex (V1), lateral occipital gyrus (LO), and fusiform gyrus (FG). Regression analyses were performed (i) to obtain correlations between time-series from each seed and all voxels in the brain, and (ii) to identify brain regions in which FC variability was related to blast mTBI severity. Blast-related mTBI severity was quantified as the sum of the severity scores assigned to each of the three most significant blast-related injuries self-reported by subjects. Correlations between FC and performance on executive functioning tasks were performed across participants with available behavioral data (n = 94). Greater blast mTBI severity scores were associated with lower FC between: (A) LGN seed and (i) medial frontal gyrus, (ii) lingual gyrus, and (iii) right ventral anterior nucleus of thalamus; (B) V1 seed and precuneus; (C) LO seed and middle and superior frontal gyri; (D) FG seed and (i) superior and medial frontal gyrus, and (ii) left middle frontal gyrus. Finally, lower FC between visual network regions and frontal cortical regions predicted worse performance on the WAIS digit-symbol coding task. These are the first published results that directly illustrate the relationship between blast-related mTBI severity, visual pathway neural networks, and executive dysfunction - results that highlight the detrimental relationship between blast-related brain injury and the integration of visual sensory input and executive processes.
Severity of Illness Index Brain Injuries, Traumatic - complications Visual Perception - physiology Veterans Humans Male Cognitive Dysfunction - etiology Cognitive Dysfunction - physiopathology Executive Function - physiology Cerebral Cortex - physiopathology Geniculate Bodies - physiopathology Young Adult Magnetic Resonance Imaging Brain Injuries, Traumatic - physiopathology Temporal Lobe - physiopathology Blast Injuries - complications Adult Female Visual Cortex - physiopathology Blast Injuries - physiopathology

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