Abstract # 2149 Poster # 79:

Scheduled for Thursday, June 21, 2007 05:00 PM-07:00 PM: Session 7 (South Main Hall) Poster Presentation

Age and Rearing Condition Influence Behavioral Responses to Social Intrusion in Rhesus Macaques (Macaca mulatta)

K. Chisholm1,2, M. Schwandt1, J. D. Higley3, S. J. Suomi2, M. Heilig1 and C. S. Barr1
1NIH/NIAAA, Laboratory of Clinical and Translational Studies-Primate Unit, Poolesville, Maryland, USA, 2NIH/NICHD, Laboratory of Comparative Ethology, 3Brigham Young University, Psychology Department
     Previous studies using the Intruder Challenge Paradigm have focused primarily on impulsive and aggressive behaviors towards the intruder. We expand on these studies and test the hypothesis that rhesus monkeys show differences in both social and nonsocial behavior when exposed to a stranger based on age and rearing condition. The subjects were 221 monkeys ranging in age from 1 to 10 years. As infants, they were reared in one of three conditions: mother-reared (MR), peer-reared (PR, reared only with same-aged peers), and surrogate peer-reared (SPR, reared in single cages with only limited daily social interactions). Subjects were exposed to the Intruder Challenge test, and their behavior was recorded for 30 minutes. The results showed that adult animals (aged 5 to 10 years) spent more time in close proximity of the intruder when compared to subadult animals (aged 1 to 4 years) [ANOVA, F(1,215)=33.51, p<0.0001]. Conversely, subadult animals spent more time in social contact with other group members compared to adult animals [F(1,215)=40.25, p<0.0001]. Rearing condition influenced the behavioral response to an intruder, with SPR animals exhibiting high levels of stereotypical behaviors [F(2,215)=6.33, p=0.0021]. This study demonstrates that age at testing and life history are both important factors in determining how macaques respond to an intruder.