Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Neurosciences, Neurosciences & Neurology, Vagus nerve, Heart rate variability, Transcutaneous vagus nerve stimulation, Acute effect, Prolonged effects, REFRACTORY EPILEPSY, PERIOD VARIABILITY, FIBERS, Adult, Aged, Analysis of Variance, Ear, Electrocardiography, Female, Heart Rate, Humans, Male, Middle Aged, Sex Characteristics, Signal Processing, Computer-Assisted, Surveys and Questionnaires, Time Factors, Transcutaneous Electric Nerve Stimulation, Vagus Nerve Stimulation, Young Adult, 1103 Clinical Sciences, 1109 Neurosciences, 1115 Pharmacology and Pharmaceutical Sciences, Neurology & Neurosurgery, 3208 Medical physiology, 3209 Neurosciences

Abstract:

The vagus nerve is strategically located in the body, and has multiple homeostatic and health-promoting effects. Low vagal activity predicts onset and progression of diseases. These are the reasons to activate this nerve. This study examined the effects of transcutaneous vagus nerve stimulation (t-VNS) on a main index of vagal activity, namely heart rate variability (HRV). In Study 1, we compared short (10 min) left versus right ear t-VNS versus sham (no stimulation) in a within-subjects experimental design. Results revealed significant increases in only one HRV parameter (standard deviation of the RR intervals (SDNN)) following right-ear t-VNS. Study 2 examined the prolonged effects of t-VNS (1 h) in the right ear. Compared to baseline, right-t-VNS significantly increased the LF and LF/HF components of HRV, and SDNN in women, but not in men. These results show limited effects of t-VNS on HRV, and are discussed in light of neuroanatomical and statistical considerations and future directions are proposed.