Sensory gating in chronic posttraumatic stress disorder: reduced auditory P50 suppression in combat veterans.
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.
Neylan
T C
TC
Department of Psychiatry, University of California, San Francisco, USA.
Fletcher
D J
DJ
Lenoci
M
M
McCallin
K
K
Weiss
D S
DS
Schoenfeld
F B
FB
Marmar
C R
CR
Fein
G
G
D001309:Auditory Threshold; D001921:Brain / Q000503:physiopathology*; D016022:Case-Control Studies; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D006185:Habituation, Psychophysiologic; D006801:Humans; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology*; D014481:United States; D014728:Veterans / Q000706:statistics & numerical data; D014744:Vietnam; D014857:Warfare