Mild Traumatic Brain Injury and Post-traumatic Stress Disorder: Difference in Brain connectivity in sensorimotor reactions tests as a differential diagnostic criterion

We investigate the characteristics of the Choice Reaction Time (CRT) and Simple Reaction Time(SRT) and brain networks in testing of Reaction of Choice (RC) and of Simple Reaction (SR) in the combat-injured Ukrainian Armed Forces service members with mild Traumatic Brain Injury (mTBI) and posttraumatic stress disorders (PTSR) who took part in combat in East Ukraine. Compared with the control group, patients with PTSD and mTBI had significantly longer SRT, but only patients with TBI had significantly longer CRT and CRT - SRT. In SR test in the PTSD group we found a shift in brain activity to the zones in the occipital area that are responsible for the primary and secondary visual information processing and a decrease in the number of interregional brain connections in the low-frequency bands that indicate more local information processing. In the mTBI group we found decreased activity in the frontal cortex and increased activity in the parietal zone, especially in the left hemisphere and only local neural networks in the high- frequency range in the fronto-parietal areas were formed. In the control group in the test of RC revealed a complete neural network of transformation of the visual stimulus in the motor response. Two interconnected frontal-parietal- occipital and tempo-parietal-occipital neural networks were identified that provide effective recognition of visual stimulus and formation of adequate, effective sensory-motor integration due to global and coordinated local processes of strategic decision-making. In the PTSD group, the СR is performed with reduced activity in the frontal area and increased activity of the ventral network and Insula of the right hemisphere, which may indicate an emotional component in the decision-making system even with respect to emotionally neutral stimuli (square and triangle). mTBI revealed dysfunction of the dorsal pathway, decreased connectivity between all brain structures and the interhemispherical interaction.

Author(s): Natalia Filimonova Taras Shevchenko National University of Kyiv, Ukraine

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