Resilience or vulnerability? thalamic subdivision connectivity in trauma-exposed individuals: a 7 t resting-state fMRI study

Abstract

Why some individuals are resilient to trauma while others develop psychopathology remains a baffling question in mental health research. Trauma-related conditions like post-traumatic stress disorder (PTSD), major depressive disorder (MDD), and anxiety disorders affect millions worldwide, emphasizing the need to understand the neural mechanisms that underlie these divergent outcomes. Through the use of ultra-high field (UHF) 7 T imaging, this study sought to investigate how thalamic functional connectivity differentiates resilience from vulnerability in trauma-exposed individuals. To that end, UHF 7 T resting-state functional magnetic resonance imaging (rs-fMRI) was applied to a group of 46 refugees from the Levant region, including 23 symptomatic (PTSD, MDD, or anxiety disorders) and 23 asymptomatic participants. Using the CONN toolbox, we conducted seed-to-voxel analyses focused on the thalamic subregions defined by the Human Brainnetome Atlas. Our results revealed significant connectivity alterations in the right medial prefrontal thalamus (mPFtha), the lateral prefrontal thalamus (lPFtha), and the occipital thalamus (Otha). Symptomatic individuals exhibited hyperconnectivity between the thalamic subregions and the somatosensory, visual, and cerebellar networks, along with reduced inter-thalamic connectivity, suggesting emotional dysregulation and hypervigilance. In contrast, asymptomatic participants displayed increased inter-thalamic connectivity and hypoconnectivity with these networks, reflecting efficient sensory integration and emotion regulation. Reduced inter-thalamic connectivity was found to correlate with lower resilience, underscoring the importance of effective thalamic communication for emotional stability. Taken together, our findings suggest that thalamic dysregulation contributes to vulnerability, while increased inter-thalamic connectivity fosters resilience through better sensory and emotion regulation. Thus, this study affords valuable insights into potential neural targets for interventions, which may help enhance resilience in trauma-exposed populations.