title: Disruption of bradycardia associated with discriminative conditioning in combat veterans with PTSD.
abstract: The effects of combat-related posttraumatic stress disorder (PTSD) on heart rate (HR) responding associated with a discriminative delay eyeblink (EB) conditioning paradigm are reported. Combat PTSD+, Combat PTSD-, and Noncombat PTSD- veterans were assessed with psychometric self-report measures, and baseline heart rate variability (HRV) was measured before receiving a 72-trial session of discriminative EB classical conditioning. Two types (red or green light) of conditioned stimuli (CS) were used: one (CS+) predicted a tone, followed immediately by an aversive stimulus (corneal airpuff); the other (CS-) predicted a tone alone, not followed by the airpuff. The light signal was presented for 5 seconds, during which HR was measured. On all psychometric measures, the PTSD+ subgroup was significantly different from the PTSD- subgroups (Combat + Noncombat), and the PTSD- subgroups did not significantly differ from each other. A linear deceleration in HR to CS+ and CS- signals was found in the combined PTSD- subgroup and on CS- trials in the PTSD+ subgroup, but was not present on CS+ trials in the PTSD+ subgroup. Results are interpreted with respect to a behavioral stages model of conditioned bradycardia and in terms of neural substrates which are both critical to HR conditioning and known to be abnormal in PTSD.
authors.affiliation: Shirley L. Buchanan Neuroscience Laboratory, Dorn VA Medical Center, 6439 Garners Ferry Road, Columbia, SC, USA. Jay.Ginsberg@va.gov
authors.forename: Jay P
authors.initials: JP
authors.lastname: Ginsberg
authors.forename: Edwin
authors.initials: E
authors.lastname: Ayers
authors.forename: Louisa
authors.initials: L
authors.lastname: Burriss
authors.forename: Donald A
authors.initials: DA
authors.lastname: Powell