Methods: Our sample (N=40) included children with clinical symptomology and typically developing children aged 9-16 years old. Participants completed a clinical interview and performed the Montreal Imaging Stress Test (MIST) in an MRI scanner. Victimization exposure was measured using the Juvenile Victimization Questionnaire (JVQ). Physiological stress response was measured with a Biopac pulsometer to calculate respiratory sinus arrhythmia (RSA) as an index of parasympathetic stress response. Brain activations were analyzed using FSL 5.0.10, and correlations between stress-dependent activation and victimization were examined independently and between groups (FWE corrected at z>2.3; p<.01 cluster thresholded).
Results: All participants showed significantly greater activation in the frontal pole, orbital frontal cortex, the insula, interior frontal gyrus (IFG), thalamus, anterior cingulate gyrus (ACG), as well as sensory regions during stress as opposed to the control condition. Participants demonstrated greater activation in reward and limbic circuitry including the hippocampus (HIP), nucleus accumbens (NA), and the frontal medial cortex during the control condition as opposed to during stress. Covariate analyses revealed victimization exposure was associated with significant activation in the left insula, frontal operculum, frontal areas, caudate and putamen.
Conclusion and Implications: Our results were consistent with the literature which indicates frontal areas are significantly activated while limbic and reward regions are suppressed during acute stress. Our finding that level of victimization exposure covaries with functional brain activity in frontal and reward regions supports the literature that toxic stress impacts brain function during development. Further, our results suggest that highly victimized youth may have to work harder to control emotional circuits during stress and may demonstrate greater reward sensitivity. Thus, social work assessment and intervention with victimized children might benefit from a strong initial focus on emotion regulation and prevention of risky behaviors.