# Manual Vagal Maneuver Effects on Cardiac Coherence, HRV, and Cognitive Performance in Young Healthy Women: A Pilot Study

## TL;DR

This pilot study explores how manual vagus nerve stimulation on the left or right side of the neck affects heart coherence, heart rate variability, and cognitive performance in young healthy women.

## Contribution

The study introduces a novel exploration of left versus right manual vagal maneuvers and their differential effects on cognitive and emotional outcomes.

## Key findings

- Left-sided manual vagal maneuver was associated with increased cardiac coherence and perceived emotional dominance.
- Both left and right manual vagal maneuvers showed improvements in attentional performance.
- No significant changes in HRV indices were observed across groups.

## Abstract

Non-invasive vagus nerve stimulation (nVNS) is gaining attention as a promising approach to modulate emotional, cognitive, and autonomic processes. This exploratory study analyzed the short-term effects of manual vagal maneuver (MVM), applied to the left or the right side of the neck (carotid region), on emotional regulation, cognitive performance, and cardiac autonomic activity in healthy young females. Sixty participants, divided equally into three groups (left MVM, right MVM, and control), completed attentional tasks under their respective conditions. Heart rate variability (HRV), cardiac coherence, self-reported emotional states, and task performance were measured. The preliminary findings of this pilot study offer mixed evidence: while both stimulation groups seem to show significant improvements in attentional performance, only left-sided MVM was associated with increased cardiac coherence and elevated perceived emotional dominance. No significant changes were observed in HRV indices across groups, highlighting potential limitations of current physiological markers in capturing subtle autonomic modulation. These preliminary findings from a pilot study suggest that, in young healthy women, stimulation—particularly on the left side—may have a potential to enhance cognitive and affective functioning, even though no detectable changes were observed in conventional HRV metrics. Given the small sample size and other important methodological limitations, such as the single-session design, these results should be interpreted with caution, and replication in larger, more rigorous studies is necessary.