A Comparative Open-Label Crossover Study of Respiratory-Gated Versus Non-Respiratory-Gated Transcutaneous Auricular Vagus Nerve Stimulation for the Treatment of Non-Motor Symptoms in Parkinson's Disease

"Stimulation Target: Left cymba conchae.~25 Hz Non-Expiratory Gated taVNS: Stimulation is delivered for 30 seconds at a frequency of 25 Hz, followed by a 30-second interval.~25 Hz Expiratory Gated taVNS: One second of stimulation occurs during exhalation at a frequency of 25 Hz.~100 Hz Expiratory Gated taVNS: One second of stimulation is administered during exhalation at a frequency of 100 Hz."