Non‐invasive vagus nerve stimulation and the motivation to work for rewards: A replication of Neuser et al. (2020, Nature Communications)

• Published in: Psychophysiology 2024-04, Vol.61 (4), p.e14484-n/a
• Main Authors: Lucchi, Federica, Lloyd, Beth, Nieuwenhuis, Sander
• Format: Article
• Language: English
• Subjects: effort; Energy metabolism; gut‐brain; HLM; Reinforcement; Replication; reproducibility; taVNS; tVNS; Vagus nerve
• ISSN: 0048-5772; 1469-8986; 1540-5958
• DOI: 10.1111/psyp.14484

The vagus nerve is thought to be involved in the allostatic regulation of motivation and energy metabolism via gut‐brain interactions. A recent study by Neuser and colleagues (2020) provided novel evidence for this process in humans, by reporting a positive effect of transcutaneous auricular vagus nerve stimulation (taVNS) on the invigoration of reward‐seeking behaviors, especially for food rewards. We conducted an independent direct replication of Neuser et al. (2020), to assess the robustness of their findings. Following the original study, we used a single‐blind, sham‐controlled, randomized cross‐over design. We applied left‐sided taVNS in healthy human volunteers (n = 40), while they performed an effort allocation task in which they had to work for monetary and food rewards. The replication study was purely confirmatory in that it strictly followed the analysis plans and scripts used by Neuser et al. Although, in line with Neuser et al., we found strong effects of task variables on effort invigoration and effort maintenance, we failed to replicate their key finding: taVNS did not increase the strength of invigoration (p = .62); the data were five times more likely (BF10 = 0.19) under the null hypothesis. We also found substantial evidence against an effect of taVNS on effort maintenance (p = .50; BF10 = 0.20). Our results provide evidence against the idea that left‐sided taVNS boosts the motivational drive to work for rewards. Our study also highlights the need for direct replications of influential taVNS studies. We were not able to replicate a study by Neuser et al. (2020, Nature Communications), which found a positive effect of transcutaneous vagus nerve stimulation on individuals' motivation to work for monetary and food rewards. Participants completed an effort allocation task while receiving non‐invasive vagus nerve stimulation, with the idea that the vagus nerve is involved in allostatic regulation of motivation.