title: Effects of Posture and Stimulus Spectral Composition on Peripheral Physiological Responses to Loud Sounds.
abstract: In the "loud-tone" procedure, a series of brief, loud, pure-tone stimuli are presented in a task-free situation. It is an established paradigm for measuring autonomic sensitization in posttraumatic stress disorder (PTSD). Successful use of this procedure during fMRI requires elicitation of brain responses that have sufficient signal-noise ratios when recorded in a supine, rather than sitting, position. We investigated the modulating effects of posture and stimulus spectral composition on peripheral psychophysiological responses to loud sounds. Healthy subjects (N = 24) weekly engaged in a loud-tone-like procedure that presented 500 msec, 95 dB sound pressure level, pure-tone or white-noise stimuli, either while sitting or supine and while peripheral physiological responses were recorded. Heart rate, skin conductance, and eye blink electromyographic responses were larger to white-noise than pure-tone stimuli (p's < 0.001, generalized eta squared 0.073-0.076). Psychophysiological responses to the stimuli were similar in the sitting and supine position (p's ≥ 0.082). Presenting white noise, rather than pure-tone, stimuli may improve the detection sensitivity of the neural concomitants of heightened autonomic responses by generating larger responses. Recording in the supine position appears to have little or no impact on psychophysiological response magnitudes to the auditory stimuli.
authors: Department of Psychiatry and Psychotherapy, University Hospital Zurich, Zurich, Switzerland.
authors: Jennifer
authors: J
authors: Koch
authors: Department of Psychiatry and Psychotherapy, University Hospital Zurich, Zurich, Switzerland.
authors: Jan
authors: J
authors: Flemming
authors: Neural Systems Group, Massachusetts General Hospital, Boston, MA, United States of America.
authors: Thomas
authors: T
authors: Zeffiro
authors: Department of Psychiatry and Psychotherapy, University Hospital Zurich, Zurich, Switzerland.
authors: Michael
authors: M
authors: Rufer
authors: Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America.
authors: Scott P
authors: SP
authors: Orr
authors: Department of Psychiatry and Psychotherapy, University Hospital Zurich, Zurich, Switzerland.
authors: Christoph
authors: C
authors: Mueller-Pfeiffer
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009622:Noise; D011187:Posture; D011601:Psychophysics; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology / Q000523:psychology; D055815:Young Adult