Neural Noise- Transcutaneous vagus nerve stimulation (tVNS) is a non-invasive way to modulate neuroplasticity; regional GABA+ signaling has been suggested to play a role.1
- In healthy adults, tVNS (200 μs pulses, 20 Hz, 30 min at the left cymba conchae) reduced total striatal GABA+, increased DLPFC glutamate content (MRS), and facilitated early-phase motor learning.1
Gardner updates
- Four-second trains of transcutaneous vagus nerve stimulation (tVNS) increased online corticospinal excitability and pupil size in humans (Journal of Neurophysiology), informing dosing and mechanism for non-invasive neuromodulation and potential BCI/neurofeedback applications.2
- The Frontiers study used proton MRS (MEGA-PRESS) on a 3T scanner to quantify GABA+ and glutamate in the left striatum, DLPFC, and sensorimotor cortex before and after 30 min of stimulation; two randomized sham-controlled experiments enrolled n=34 (Exp. 1) and n=27 (Exp. 2) healthy right-handed adults.1
- Key neurochemical results (Experiment 1): striatal GABA+ significantly decreased after tVNS vs. baseline (p=0.041, Cohen’s d=−0.48); DLPFC glutamate significantly increased (p=0.030, Cohen’s d=0.53); no significant changes in sensorimotor cortex or in the sham group.1
- Key behavioral result (Experiment 2): force-control motor error was significantly lower at the 10-min timepoint of tVNS vs. sham (p=0.023, Cohen’s d=−1.04), indicating facilitation of early-phase motor learning; effects did not persist at later timepoints in this experiment.1
- The proposed mechanism is that tVNS-mediated reduction in striatal inhibitory tone (via GABA+) combined with increased prefrontal excitatory drive (via glutamate) lowers the threshold for plasticity induction during motor practice.1
- tVNS may have clinical relevance for post-stroke motor rehabilitation: excessive tonic GABAergic inhibition is known to impair motor recovery, and tVNS offers a portable, non-pharmacological route to modulate this.1
- A complementary 2025 study confirmed that taVNS reduces position errors in force-field learning in healthy adults (online effect, no next-day retention), establishing tVNS as a timing-sensitive modulator of error-based motor learning.3
- Potential concern: timing matters — administering tVNS at nonspecific timings throughout training has been shown to attenuate motor adaptation in healthy humans rather than enhance it, underscoring the importance of protocol design.3