Paired vagus nerve stimulation (VNS) for rehabilitation

A therapy in which a brief vagus nerve stimulation is delivered at the moment of a rehabilitation movement, so the burst of neuromodulatory drive it evokes (acetylcholine, noradrenaline) coincides with, and reinforces, the motor activity being trained. The transient neuromodulator release is thought to act as a plasticity 'enabling' or gating signal, tagging the co-active circuits for strengthening — an engineered form of activity-dependent plasticity in which the pairing is between a movement and a global plasticity-permissive state rather than between two specific neural sites.

Honesty: this is one of the few plasticity-paired approaches with regulatory approval and a positive pivotal randomized trial for chronic ischemic-stroke arm rehabilitation, showing gains over sham stimulation paired with the same therapy. Caveats remain: it requires a surgically implanted vagus stimulator, effect sizes are meaningful but moderate, and it targets a permissive neuromodulatory signal rather than a specific pathway, so it complements rather than replaces task-specific training.