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A bihemispheric autonomic model (BHAM) may support advanced understanding of traumatic stress effects on physiology and behavior. The model builds on established data showing hemispheric lateralization in management of the autonomic nervous system, and proposes that traumatic stress can produce dominant asymmetry in activity of bilateral homologous brain regions responsible for autonomic management. Rightward and leftward dominant asymmetries are associated with sympathetic high arousal or parasympathetic freeze tendencies, respectively, and return to relative symmetry is associated with improved autonomic regulation. Autonomic auto-calibration for recovery (inverse of Jacksonian dissolution proposed by polyvagal theory) has implications for risk behaviors associated with traumatic life stress. Trauma-induced high arousal may be associated with risk for maladaptive behaviors to attenuate arousal (including abuse of alcohol or sedative-hypnotics). Trauma-induced freeze mode (including callous-unemotional trait) may be associated with low resting heart rate and risk for conduct disorders. The model may explain higher prevalence of leftward hemispheric abnormalities reported in studies of violence. Implications of the BHAM are illustrated through case examples of a military special operations officer with history of traumatic brain injury and post-traumatic stress disorder, and a university student with persisting post-concussion symptoms. Both undertook use of a noninvasive closed-loop neurotechnology – high-resolution, relational, resonance-based, electroencephalic mirroring – with ensuing decrease in hemispheric asymmetry, improvement in heart rate variability, and symptom reduction. Finally, the BHAM aligns with calls for researchers to use brain-behavioral constructs (research domain criteria or RDoC, proposed by the National Institutes of Mental Health) as building blocks for assessment and intervention in mental health science.

BACKGROUND AND PURPOSE: Brain asymmetries are reported in posttraumatic stress disorder, but many aspects of laterality and traumatic stress remain underexplored. This study explores lateralization changes in resting state brain network functional connectivity in a cohort with symptoms of military-related traumatic stress, associated with use of a closed-loop neurotechnology, HIRREM. METHODS: Eighteen participants (17 males, mean age 41 years [SD = 7]) received 19.5 (1.1) HIRREM sessions over 12 days. Whole brain resting magnetic resonance imaging was done pre- and post-HIRREM. Laterality of functional connectivity was assessed on a whole brain basis, and in six predefined networks or regions. Laterality of connectivity within networks or regions was assessed separately from laterality of connections between networks or regions. RESULTS: Before HIRREM, significant laterality effects of connection type (ipsilateral for either side, or contralateral in either direction) were observed for the whole brain, within networks or regions, and between networks or regions. Post-HIRREM, there were significant changes for within-network or within-region analysis in the motor network, and changes for between-network or between-region analyses for the salience network and the motor cortex. CONCLUSIONS: Among military service members and Veterans with symptoms of traumatic stress, asymmetries of network and brain region connectivity patterns were identified prior to usage of HIRREM. A variety of changes in lateralized patterns of brain connectivity were identified postintervention. These laterality findings may inform future studies of brain connectivity in traumatic stress disorders, with potential to point to mechanisms of action for successful intervention.

BACKGROUND AND PURPOSE: Post‐traumatic stress disorder is associated with connectivity changes in the default mode, central executive, and salience networks, and other brain regions. This study evaluated changes in network connectivity associated with usage of High‐resolution, relational, resonance‐based electroencephalic mirroring (HIRREM(®); Brain State Technologies, Scottsdale, AZ), a closed‐loop, allostatic, acoustic stimulation neurotechnology, for military‐related traumatic stress. METHODS: Eighteen participants (17 males, mean age 41 years [SD = 7], 15 active duty) enrolled in an IRB approved pilot trial for symptoms of military‐related traumatic stress. Participants received 19.5 (1.1) HIRREM sessions over 12 days. Symptoms, physiological and functional measures, and whole brain resting MRI were collected before and after HIRREM. Six whole brain functional networks were evaluated using summary variables and community structure of predefined networks. Pre to postintervention change was analyzed using paired‐sample statistical tests. RESULTS: Postintervention, there was an overall increase in connectivity of the default mode network (P = .0094). There were decreases of community structure in both the anterior portion of the default mode (medial prefrontal cortex, P = .0097) and in the sensorimotor (P = .005) network. There were no statistically significant changes at the whole brain level, or in the central executive, salience, or other networks analyzed. Participants demonstrated significant improvements in clinical symptoms, as well as autonomic cardiovascular regulation, which have been reported previously. CONCLUSIONS: Use of closed‐loop, allostatic, acoustic stimulation neurotechnology (HIRREM) was associated with connectivity changes in the default mode and sensorimotor networks, in directions that may have explained the subjects' clinical improvements.