# Transcutaneous vagus nerve stimulation reduces total striatal GABA+ content, increases DLPFC Glu content, and facilitates early-phase motor learning

## TL;DR

Transcutaneous vagus nerve stimulation (tVNS) lowers GABA in the striatum and raises glutamate in the prefrontal cortex, improving early motor learning in healthy adults.

## Contribution

This study provides empirical evidence that tVNS modulates brain neurotransmitter levels and enhances motor learning.

## Key findings

- tVNS significantly reduced GABA+ levels in the left striatum.
- tVNS increased Glu levels in the dorsolateral prefrontal cortex.
- tVNS improved motor task performance in early-phase learning.

## Abstract

Transcutaneous vagus nerve stimulation (tVNS) has emerged as a promising non-invasive technique for modulating neuroplasticity. Previous studies have suggested that changes in regional brain GABA+ signaling contribute to these effects, but empirical neurophysiological evidence remains limited.

We investigated the neurophysiological and behavioral effects of tVNS (200-μs pulses at 20 Hz, alternating 30 s ON–1 s OFF cycles, 30 min total duration) in healthy adults using two experimental paradigms. In Experiment 1, GABA+ and Glutamate (Glu) levels were measured in the left striatum (STR), dorsolateral prefrontal cortex (DLPFC), and sensorimotor cortex (SM) of 34 participants by proton magnetic resonance spectroscopy (1H-MRS), before and after ipsilateral tVNS. In Experiment 2, 27 participants performed a right-hand force-control motor learning task before, during, and after tVNS.

Administration of tVNS significantly reduced GABA+ levels in the left STR (p < 0.05), increased Glu levels in the DLPFC (p < 0.05), and significantly improved motor task performance compared to the sham group at 10 min after stimulus onset (p < 0.05).

tVNS (1) reduced striatal GABA+ levels and increased DLPFC Glu in healthy adults, and (2) facilitated early-phase motor learning. These findings support the use of tVNS as a noninvasive intervention that enhances motor learning in neurorehabilitation and the treatment of motor disorders.