Neural NoiseVagus nerve stimulation (VNS) delivers electrical impulses to the vagus nerve — the longest cranial nerve, running from the brainstem through the neck to the thorax and abdomen — to modulate neural circuits involved in epilepsy, depression, inflammation, and motor recovery. Implantable VNS, first FDA-approved for drug-resistant epilepsy in 1997 and later for treatment-resistant depression, uses a pulse generator in the chest connected to a lead wrapped around the left cervical vagus nerve. By activating afferent fibers that project to the nucleus tractus solitarius and onward to widespread cortical and subcortical targets, VNS alters excitability in seizure networks and modulates noradrenergic and serotonergic tone relevant to mood regulation.
Transcutaneous VNS (tVNS) applies stimulation non-invasively through the skin at the ear (auricular branch) or neck (cervical), offering a lower-risk alternative for research and emerging clinical applications. Studies of tVNS have explored effects on cognitive enhancement, motor learning, autonomic regulation, and neuroinflammation, though evidence for many of these indications remains preliminary compared with the well-established implantable form.
A growing body of clinical evidence supports VNS as an adjunct to rehabilitation after stroke, where stimulation paired with motor training enhances cortical plasticity and accelerates upper-limb recovery. The convergence of VNS with bioelectronic medicine — treating disease by modulating electrical signaling in nerves — positions it as a bridge between traditional neuromodulation and broader applications in immunology and metabolic regulation. Closed-loop VNS systems that adjust stimulation based on real-time biomarkers such as heart rate variability or EEG signatures represent an active frontier in adaptive neuromodulation.