Abstract # 94:

Scheduled for Sunday, September 14, 2014 11:25 AM-11:40 AM: Session 14 (Mary Gay) Oral Presentation


A. F. Hamel1, C. K. Lutz2, K. Coleman3, J. M. Worlein4, E. J. Peterson1, K. L. Rosenberg5, J. S. Meyer1,5 and M. A. Novak1,5
1University of Massachusetts Amherst, Neuroscience and Behavior Graduate Program, Amherst, MA 01003, USA, 2Southwest National Primate Research Center, 3Oregon National Primate Research Center, 4Washington National Primate Research Center, 5Department of Psychological and Brain Sciences, University of Massachusetts Amherst
     In the Human Intruder Test (HIT) monkeys are exposed to an unfamiliar experimenter and their reactivity is assessed. The HIT paradigm is composed of 4 consecutive, two-minute phases: a Baseline phase (no intruder) and three experimental phases which vary the orientation of the experimenter to the subject (Profile, Stare, and Back). The HIT was administered twice to 145 (55% male) rhesus monkeys (Macaca mulatta) housed at 4 national primate centers, with a 3 week inter-trial interval, during which time hair samples were collected. All trials were videotaped and hair samples were analyzed for cortisol concentration by enzyme immunoassay. Videotapes were scored for presence and duration of specific target behaviors (inter-observer reliability >90%). Hair cortisol concentrations were used to stratify subjects into 3 equal groups: high, intermediate, and low cortisol phenotypes. Behavior of high (mean=80.77 pg/ml) and low phenotypes (mean=41.53 pg/ml) were compared using a repeated measures ANOVA (between subjects variable: cortisol phenotype; within subjects variable: HIT phase). High cortisol phenotypes were more reactive to the presence of the intruder, spending significantly more time at the back of the cage during the Profile phase (F(3)=3.261, p=0.022) and threatening the intruder significantly more during the Stare phase (F(4)=4.019, p=0.034) than low cortisol phenotypes. Monkeys responded to the presence of the intruder as expected yet those with higher levels of HPA axis activity are correspondingly more behaviorally reactive.