Figure 1.
Tasks used to assess the influence of 5-HTTLPR genotype on social reward and punishment.
(A) Stimuli consisted of images of familiar conspecifics. Image pools used in the pay-per-view and primed risk taking task were identical, and consisted of four categories: gray square, faces of familiar low status individuals, faces of familiar high status individuals, and perinea of familiar females. Each of the three latter image pools consisted of 60 different images of either three (face pools) or four (perinea pool) different individuals. Images used for the free viewing task consisted of high and low status faces similar, but not identical, to those used in the other two tasks; and scrambled faces. Trial structures and reward schedules for (B) the free viewing task, (C) primed risk taking task, and (D) pay-per-view task. Stimuli for the free viewing task were randomly interleaved. The risk taking and pay-per-view tasks utilized a blocked trial structure so that reward contingencies were apparent to the animal after sampling each option.
Figure 2.
Serotonin transporter genotype influences eye position and pupil diameter when observing social images.
(A) In contrast to L/L monkeys, S/L monkeys looked less at the picture when the image depicted a face than when it depicted a scrambled face (* indicates p = 0.02) and (B) spent less time looking in the eye region when face images were presented. Additionally, both L/L and S/L monkeys spent less time looking in the eye region of high status faces than low status faces (* indicates p = 0.02, ** indicates p = 0.01). (C) When observing faces, the pupil diameter of S/L monkeys was modulated by the social status of the displayed face, with a greater mean pupil diameter induced by the presentation of high-status faces (* indicates p = 0.05). In contrast, no significant difference in the pupil diameters of L/L animals was observed to correlate with image category.
Figure 3.
Serotonin transporter genotype influences socially primed risk-sensitivity.
(A) Preference for the risky option was suppressed in S/L macaques when primed with a dominant face (* indicates p<0.001). Choices did not differ in L/L and S/L animals when primed with a gray square, subordinate face, or perinea. (B) Each individual L/L subject in the study showed an increased preference for the risky option, and each individual S/L subject showed a decreased preference for the risky option, when primed with a high status face versus a gray square.
Figure 4.
Serotonin transporter genotype modulates social reinforcement in a pay-per-view task.
L/L animals sacrificed juice to see high status faces, while S/L monkeys required overpayment to view the same images. Circles indicate mean orienting value for each individual subject.