Brain signaling dynamics after vagus nerve stimulation

The vagus nerve projects to a well-defined neural circuit via the nucleus tractus solitarii (NTS) and its stimulation elicits wide range of metabolic, neuromodulatory, behavioral effects. Transcutaneous (tVNS) has been established as promising technique non-invasively alter brain function. However, precise dynamics elicited by tVNS in humans are still largely unknown. Here, we performed fMRI with concurrent right-sided (vs. sham) following randomized cross-over design (N = 40). First, unravel temporal profile tVNS-induced changes NTS, compared time series canonical profiles for ON OFF cycles. Model comparisons indicated that NTS were best fit block-wise shifts signal amplitude estimates being highly correlated. Therefore, (ON + OFF) versus baseline phases found increased BOLD activation but this effect was dependent on sufficient signal-to-noise ratio (tSNR) mask. Second, identify spatiotemporal evolution brain, examined lagged co-activation patterns phase coherence. In contrast our hypothesis, did not dynamic functional connectivity after correction multiple comparisons. Third, establish positive control future research, measured gastric myoelectrical frequency an electrogastrogram. Again, induced no frequency. Collectively, study provides evidence can perturb signaling these effects tSNR require localization. light absence acute motility, discuss which steps necessary advance research afferent efferent tVNS.