Good vibrations: Sternal vibration enhances white matter density and interoceptive awareness.

Vibration-based therapies are understudied but promising methods for alleviating psychiatric symptoms, particularly when paired with behavioral practices. The potential neuroplastic changes associated with a novel neurostimulation method, sternal vibration, and associations with clinical change remain unknown. We examined effects of sternal vibration paired with mindfulness meditation on change in white matter microstructure and dissociation using neurite orientation dispersion and density imaging (NODDI) in trauma-exposed adults with elevated dissociative symptoms. A total of 116 trauma-exposed adults with elevated dissociation completed MRI before/after eight mindfulness meditation sessions. Approximately half (n=60) received sternal vibration augmentation whereas n=56 had no augmentation. Self-reported dissociation was measured at each session with the Scale of Body Dissociation. Significant time-by-intervention type interactions showed vibration-specific improvements in body awareness (p=.032; η p 2 =.139) and increased neurite density index (NDI) in a region within the corticospinal tract (CST), the left cerebral peduncle (CP, p<.01, η p 2 =.102, k=15 voxels). This finding replicated in tractography analyses showing increased NDI in left (p=.007; η p 2 =.066) and right CST (p=.004; η p 2 =.075). Decreased body dissociation associated with increased CP NDI in those who received vibration (p=.011, η p 2 =.058); no associations between clinical and white matter change were observed with non-vibration interventions. Findings indicate that brief sternal vibration in the context of mindfulness meditation enhanced body awareness and neurite density in a tract of relevance to somatosensory integration. White matter changes corresponded with enhanced interoceptive awareness. Findings reveal the promise of sternal vibration as a low-cost, non-invasive neurostimulation method for enhancing interoception via neuroplastic alterations, with applications for various psychiatric populations.