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Sensory gating in chronic posttraumatic stress disorder: reduced auditory P50 suppression in combat veterans
T C Neylan1, D J Fletcher, M Lenoci
1Department of Psychiatry, University of California, San Francisco, USA.
Background:
Posttraumatic stress disorder (PTSD) may be associated with a general impairment of cognitive function that extends beyond the processing of trauma-specific stimuli. Suppression of the auditory P50 response to repeated stimuli occurs in normal subjects and reflects the central nervous system's ability to screen out repetitive stimuli, a phenomenon referred to as sensory gating. This study examines P50 sensory gating to nonstartle auditory stimuli in PTSD subjects and normal controls.
Methods:
P50 generation and gating were studied using a conditioning/testing paradigm in 15 male subjects with PTSD and 12 male controls. P50 test/conditioning (T/C) ratios were estimated using the Singular Value Decomposition method.
Results:
The amplitude of the P50 response to the conditioning stimulus did not differ in subjects with PTSD compared to normal controls. The P50 T/C ratio is increased in PTSD subjects (mean = .408, SD = .275) as compared to the controls (mean = .213, SD = .126, two tailed t, p = .024).
Conclusions:
This study provides evidence that PTSD is associated with impaired gating to nonstartle trauma-neutral auditory stimuli.