In vivo tracing of the ascending vagal projections to the brain with manganese enhanced magnetic resonance imaging

Introduction The vagus nerve, the primary neural pathway mediating brain-body interactions, plays an essential role in transmitting bodily signals to brain. Despite its significance, our understanding of detailed organization and functionality vagal afferent projections remains incomplete. Methods In this study, we utilized manganese-enhanced magnetic resonance imaging (MEMRI) as a non-invasive vivo method for tracing nerve brainstem assessing their functional dependence on cervical stimulation (VNS). Manganese chloride solution was injected into nodose ganglion rats, T1-weighted MRI scans were performed at both 12 24 h after injection. Results Our findings reveal that neurons can uptake transport manganese ions, serving surrogate calcium nucleus tractus solitarius (NTS) brainstem. absence VNS, observed significant contrast enhancements around 19–24% NTS ipsilateral injection side. Application VNS 4 further promoted activity, leading greater 40–43% NTS. Discussion These results demonstrate potential MEMRI high-resolution, activity-dependent afferents, providing valuable tool structural assessment influence brain activity.