This protocol focuses on two measures of autonomic control to quantify central actions of oxytocin. First, the study team proposes to examine the influence of oxytocin on heart rate variability with focus on its effect on high frequency variability, most commonly ascribed to parasympathetic nervous system activity acting to brake sympathetic tone. Intranasal oxytocin has been demonstrated to have a large effect size on this measure which can be repeated at frequent intervals. As a secondary assessment of parasympathetic activity, the study team will measure low frequency fluctuation in pupil diameter, termed hippus, which also reflects parasympathetic nervous system activity. This outcome measure can be assessed in 3 seconds using equipment currently being used under Institutional Review Board (IRB) approved protocols.
The goal of this study is to test the effects of oxytocin on heart rate variability and pupil diameter, both of which have subtle effects on the activity rate of the autonomic nervous system.