taVNS to Reduce PTSD Symptoms in WTC Responders

The non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) device that will be used in this study is a wearable TENS unit called the Vorso STIM100 System. The Vorso system consists of a wearable, external stimulator, a neural interface ear piece, and an arm band designed to be safe for human contact. The external stimulator generates electrical pulses that are transcutaneously delivered to the auricular branch of the vagus nerve through the ear canal. The ear piece contains 4 electrodes that carry current from the external stimulator to the auricular branch of vagus nerve. The external stimulator connects to a flexible arm band that attaches to the upper arm for ease of use during each stimulation session. The type of stimulation (including shape, frequency, pulse width, amplitude, total charge, and energy delivered) is comparable to the levels applied by commercially available TENS stimulators. The sham control group will not receive any stimulation.