Abstract # 114:

Scheduled for Sunday, September 14, 2014 01:45 PM-02:00 PM: Session 18 (Henry Oliver) Oral Presentation


DIFFERENCES IN SEROTONIN TRANSPORTER DENSITY IN THE AMYGDALA OF BONOBOS (PAN PANISCUS) AND CHIMPANZEES (PAN TROGLODYTES): IMPLICATIONS FOR THE REGULATION OF SOCIAL BEHAVIOR

C. D. Stimpson1, W. D. Hopkins2,3, J. P. Taglialatela3,4, N. Barger5, P. R. Hof6 and C. C. Sherwood1
1The George Washington University, 2110 G St., NW, Washington, DC 20052, USA, 2Georgia State University, 3Yerkes National Primate Research Center, 4Kennesaw State University, 5University of California, Davis, 6Icahn School of Medicine at Mount Sinai
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     Despite diverging only around two million years ago and sharing over 99% of their genetic material, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes) differ greatly in social behavior. Specifically, chimpanzees are more likely to display aggression in the context of intragroup interactions and during encounters between communities. Bonobos, however, are generally regarded as more tolerant and tend to mediate conflicts through sexual behavior rather than aggressive interactions. Recent studies have demonstrated anatomical differences between the two species in the amygdala, an area of the brain that serves a role in decision making, memory, attention and emotional responses. In the current study, we sought to determine whether the amygdala shows a measureable difference in serotonin transporter (SERT) expression between bonobos (N=6) and chimpanzees (N=6). SERT is known to regulate the responsiveness of the amygdala to stimuli that provoke fear and aggression. We used immunohistochemistry to label SERT-containing axons and stereological methods to estimate their length density. We found that bonobos express a significantly greater density of SERT-immunoreactive axons across the entire amygdala, at levels twice those observed in chimpanzees (Mann-Whitney U, p = 0.008). These findings suggest that variation in serotonin levels in the amygdala mediate, in part, the remarkable differences in social behavior exhibited by bonobos and chimpanzees. James S. McDonnell Foundation (220020293)