2026.10.07
A New Clue for Assessing the Body's Response to Mild Electrical Stimulation of the Ear: Changes in Heart Rate Regulation Observed in 17 of 18 Participants
Key points
- Eighteen healthy adult men received transcutaneous auricular vagus nerve stimulation (taVNS), with electrocardiograms and continuous blood pressure recorded before, during and after stimulation.
- Heart rate adjustments in response to blood pressure changes were smaller during stimulation than before stimulation, and 17 of the 18 participants showed a change in the same direction.
- Baroreflex sensitivity (BRS), which quantifies these adjustments, may one day serve as a "yardstick" for assessing the body's response during stimulation and tailoring stimulation settings to each individual.
A research group at Niigata University, including graduate student KATAHARA Yusuke of the Graduate School of Science and Technology, Professor IIJIMA Atsuhiko of the School of Health Sciences, Faculty of Medicine, and the Faculty of Engineering, and Professor TAINAKA Kazuki of the Brain Research Institute, investigated a way to determine not only whether a device delivers transcutaneous auricular vagus nerve stimulation (taVNS)1, which applies mild electrical stimulation to the ear, but also whether the body actually responds to it. In 18 healthy adult men, baroreflex sensitivity (BRS)2—a measure of how much heart rate adjusts to changes in blood pressure—was lower during stimulation than before stimulation, decreasing in 17 of the 18 participants. Systolic blood pressure, the top number in a blood pressure reading, was about 6 mmHg higher on average, whereas no clear differences were detected in measures such as heart rate variability. BRS may capture physiological changes during stimulation that other measures do not readily reveal. If these findings are replicated in future controlled trials, BRS could help confirm the body's response in each stimulation session and tailor settings such as stimulation intensity and electrode position to each individual. At this stage, however, BRS has not been established as a measure for diagnosing disease or determining treatment effectiveness in the context of taVNS. These findings were published in Scientific Reports on October 6, 2026.
Term explanations
1. Transcutaneous Auricular Vagus Nerve Stimulation (taVNS)
A method that applies mild electrical stimulation to the ear to send sensory signals to the brain through the auricular branch of the vagus nerve. It requires no surgery and does not directly stimulate the vagus nerve fibres leading to the heart.
2. Baroreflex Sensitivity (BRS)
A measure of how much the interval between heartbeats changes as blood pressure rises or falls. A higher value indicates a larger adjustment in the interval between heartbeats in response to a given change in blood pressure.
Publication Details
Journal: Scientific Reports
Title: Acute transcutaneous auricular vagus nerve stimulation is associated with lower baroreflex sensitivity without detectable Mayer-wave coherence change: an exploratory study
Authors: Yusuke Katahara, Atsuhiko Iijima, Kazuki Tainaka
DOI: 10.1038/s41598-026-71625-9
