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The auditory startle response in post-traumatic stress disorder.
S E Siegelaar1, M Olff, L J Bour
1Department of Neurology H2-222 and Clinical Neurophysiology, Academic Medical Centre, PO Box 22660, 1100 DD, Amsterdam, The Netherlands.
Experimental Brain Research
|March 10, 2006
Summary
Post-traumatic stress disorder (PTSD) patients exhibit prolonged muscle response times and enhanced autonomic responses to startling stimuli. However, the overall size of the auditory startle reflex (ASR) does not differ between PTSD patients and healthy individuals.
Area of Science:
- Neuroscience
- Psychology
- Human Physiology
Background:
- Post-traumatic stress disorder (PTSD) is associated with exaggerated startle responses.
- Previous research suggests heightened autonomic and muscle responses in PTSD patients.
Purpose of the Study:
- To investigate the generalized auditory startle reflex (ASR) pattern in PTSD.
- To compare EMG and psychogalvanic reflex (PGR) responses to auditory stimuli between PTSD patients and controls.
Main Methods:
- Studied EMG responses in seven muscles and PGR in 10 PTSD patients and 11 healthy controls.
- Measured latency, amplitude, and duration of EMG responses and PGR amplitude to auditory stimuli.
- Analyzed differences in startle reflex size, muscle activation, and autonomic responses.
Main Results:
- No significant difference in the overall size of the ASR or orbicularis oculi (OO) muscle response between groups.
- Prolonged EMG latencies observed in the sternocleidomastoid (SC) and deltoid (DE) muscles in PTSD patients.
- A late OO muscle response (orienting reflex) and enlarged PGR amplitude were more frequent in PTSD patients.
Conclusions:
- The generalized ASR size is not enlarged in PTSD.
- Prolonged EMG latencies in specific muscles and altered autonomic responses differentiate PTSD patients.
- Late OO muscle responses and enhanced PGR can distinguish PTSD patients from controls.