Wednesday, January 14, 2009

Look me in the eye!   posted by Razib @ 1/14/2009 07:29:00 PM

Serotonin Transporter Genotype Modulates Social Reward and Punishment in Rhesus Macaques (paper is OA, so click through for stats & charts):
Serotonin signaling influences social behavior in both human and nonhuman primates. In humans, variation upstream of the promoter region of the serotonin transporter gene (5-HTTLPR) has recently been shown to influence both behavioral measures of social anxiety and amygdala response to social threats. Here we show that length polymorphisms in 5-HTTLPR predict social reward and punishment in rhesus macaques, a species in which 5-HTTLPR variation is analogous to that of humans.

In contrast to monkeys with two copies of the long allele (L/L), monkeys with one copy of the short allele of this gene (S/L) spent less time gazing at face than non-face images, less time looking in the eye region of faces, and had larger pupil diameters when gazing at photos of a high versus low status male macaques. Moreover, in a novel primed gambling task, presentation of photos of high status male macaques promoted risk-aversion in S/L monkeys but promoted risk-seeking in L/L monkeys. Finally, as measured by a "pay-per-view" task, S/L monkeys required juice payment to view photos of high status males, whereas L/L monkeys sacrificed fluid to see the same photos.

ScienceDaily has an interesting tidbit:
In a series of experiments, the S version of the gene in monkeys was found to influence their risk-taking when faced with particular social stimuli.

"Based on work in humans, we interpreted this to reflect an induction of a fearful emotional state, which often leads people to become risk averse," said Karli Watson, Ph.D., of the Duke Department of Neurobiology, lead author on the paper.

In human populations of European ancestry, 48% are S/L and 36% are L/L. The rest are S/S. The S allele is more common in Asian populations, Watson noted.

More on 5-HTTLPR.