Pharmaco-Neuroimaging Studies of Approach/Avoidance Behaviors and Post-Mortem Studies: Study 1.2 (Stress Manipulation)

Electrotactile stimulation will be used as the aversive stimulus. The aversive stimulus is delivered in the form of a mild half-second stimulation to the ankle, calibrated to a subjective threshold that is uncomfortable but not painful. This stimulation is delivered by Digitimer DS8R Constant Current Stimulator (Digitimer North America, LLC. Ft. Lauderdale, FL). Its previous model DS71 has been safely implemented in studies with previously MGH-approved IRB's (Milad et al., 2013).