Abstract # 145:

Scheduled for Friday, June 21, 2013 03:50 PM-04:05 PM: Session 20 (San Geronimo Ballroom C) Oral Presentation


VARIABILITY IN RHESUS MACAQUES’ FEAR REACTIONS TO A SNAKE IN A NATURAL SETTING.

H. Bravo-Rivera1,2, A. Mas2, D. Merced1, J. Ayala2 and G. J. Quirk1
1University of Puerto Rico School of Medicine, San Juan, PR, Laboratory of fear learning Centro Medico School of Medicine Ofc 231A 2nd Floor Main Bldg, 1The Caribbean Primate Research Center, Depts. of Psychiatry and Anatomy & Neurobiology, San Juan , Puerto Rico 00935, USA, 2Caribbean Primate Research Center
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     Innate Fear reactions in monkeys are most often studied in laboratory settings (Mineka and Cook, 1993; Izquierdo and Murray, 2004). However, Fear responses are better studied in natural settings devoid of captivity-associated stressors.   We therefore studied the reactions of 170 free-ranging Rhesus macaques to a rubber Snake in Cayo Santiago, an island facility in Puerto Rico.   Monkeys were trained to retrieve a grape from a bin with a hinged lid. In a test trial, opening the bin revealed a dangling rubber Snake. Our measure of Fear consisted of the ratio of lid-holding time for the Snake trials vs. food trials (snake/food) (fearful: <1; fearless: ?1).  Of 170 monkeys, 132 (78%) showed a fearful response whereas 38 (22%) showed a fearless response. A blue ball elicited almost no Fear. A plot of Fear vs. age revealed that most monkeys 5-12 years old were fearful (% 89), however, monkeys 12-23 were bimodally distributed (% 42 fearless, % 58 fearful). Thus, reaching middle-advanced age increases the chance for a monkey to exhibit fearless behavior in this task. These findings suggest the existence of biological and/or environmental factors that interact with the age to modulate Fear expression. Genetic data from these monkeys are currently being analyzed by Jeffrey Rogers, Ph.D., and collaborators at Baylor College of Medicine.