Objective: This study was designed to examine startle response and physiologic stress response measured by changes in heart rate and galvanic skin conductance to mental imagery. The goal is to examine the influence of perceived levels of stress and previous trauma history on startle potentiation and autonomic physiologic responses to pleasant, unpleasant and neutral standardized scenarios. The experimental setup created in this project will be used for a study on psychogenic movement disorder (PMD) patients in the future.
Background: Startle potentiation and changes in autonomic physiologic measures such as changes in heart rate and galvanic skin conductance are reliable measures of physiologic arousal. Emotionally aversive imagery is a way of modulating startle response and has been shown to lead to greater physiologic arousal in patients with posttraumatic stress disorder. Interestingly, patients with a history of multiple traumata have shown less physiologic arousal to aversive imagery compared to healthy controls and patients with a single trauma history in a previous study.
Methods: Participants are listening to 15 standardized scenarios (ANET; affective norms for English text) with unpleasant, pleasant and neutral conditions. Study subjects are asked to actively imagine the scenes which are presented in a pseudorandomized fashion for three trials each. The startle reflex is elicited in 3/15 scenarios by a rapid onset white noise burst probe after the auditory stimuli are presented. Heart rate, galvanic skin conductance and startle reflex are measured and subjects are asked to rate the level of emotional pleasure associated with each scenario. During data analysis, the amplitude of the startle reflex and changes in other autonomic measures are compared between the three conditions.
Results: Preliminary data analysis in healthy volunteers suggests that the combination of startle probe with aversive imagery lead to lower valence reporting and increased amplitude of the startle reflex.
Future goals: The project will study differences in startle response and autonomic reactivity to standardized auditory imagery between PMD patients and healthy volunteers and correlate outcomes with previous trauma history and perceived levels of stress.
Last updated December 14, 2012