The pro-cognitive effects of Vagus Nerve Stimulation (VNS) observed in some small offlabel studies have raised enthusiasm for its use to ameliorate cognitive performance. Relatedly, auricular transcutaneous VNS (atVNS) has gained a lot of attention as the most affordable, non-invasive VNS technique. Unfortunately, mechanisms underlying atVNS cognitive effect are still unclear. Further research in the mouse is required. So far it has been limited to acute non-invasive stimulation, or to chronic invasive ...
The pro-cognitive effects of Vagus Nerve Stimulation (VNS) observed in some small offlabel studies have raised enthusiasm for its use to ameliorate cognitive performance. Relatedly, auricular transcutaneous VNS (atVNS) has gained a lot of attention as the most affordable, non-invasive VNS technique. Unfortunately, mechanisms underlying atVNS cognitive effect are still unclear. Further research in the mouse is required. So far it has been limited to acute non-invasive stimulation, or to chronic invasive stimulation. While the underlying effects of acute stimulation are probably far from the physiological and molecular pathways activated in chronic stimulation, invasivity is accompanied by surgical challenges and morbidity. There is a need for a simple, well-characterized, and reliable non-invasive chronic atVNS technique. In the present study, after intense trial and error, we design and produce the S-pod: a device in the form of an ear pod for atVNS in mice. To test proper functioning, we corroborate the already proven memory persistence enhancement triggered by acute atVNS in anesthetized naïve mice in a novel object-recognition test. The implementation of an innovative technique to test the stimulation sites, and the steadiness of the S-pod in the concha might make the results more reproducible than the ones obtained with the previous and only atVNS device for mice, also designed by our group. A further advantage of the S-pod with respect to the previous atVNS device is its compatibility with a proposed preliminary model of a chronic atVNS setup for electrostimulation in non-anesthetized mice. The latter includes an Elizabethan collar to avoid ear scratching, for which a habituation validation in CD-1 mice is provided. The present work supposes a first step to implementing non-invasive chronic atVNS in mice. Further research could conceivably open new doors to unearthing the molecular, neurological, and anatomical mechanisms underlying the cognitive effect of chronic atVNS.
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