Locus coeruleus fMRI response to transcutaneous auricular vagus nerve stimulation is coupled to changes in salivary alpha amylase

Christoph Schneider, Nikos Priovoulos, Prokopis C. Prokopiou, Frans R.J. Verhey, Benedikt A. Poser, Dimo Ivanov, Roberta Sclocco, Vitaly Napadow, Heidi I.L. Jacobs

Transcutaneous auricular vagus nerve stimulation (taVNS) has shown promise to non-invasively enhance memory in older adults and those with mild cognitive impairment (MCI) [1,2]. Evidence suggests this effect is mediated by stimulation of the locus coeruleus (LC), a small but critical brainstem nucleus that releases noradrenaline (NA), a neurotransmitter pivotal for attention and memory. Specifically, animal studies indicate that vagus nerve stimulation increases LC firing [3], and human studies have demonstrated taVNS-evoked LC Blood Oxygen Level Dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) response [4] and higher salivary alpha-amylase (sAA) levels [5], a proxy for peripheral NA release.