br Methods br Results br Discussion In a
Discussion In a sample of typically developing community adolescents, those who had engaged in higher risk sexual behaviors differed in neural response and functional connectivity to social reward. Adolescents with higher-risk sexual behavior had greater activation than adolescents with lower-risk sexual behavior in social reward-network regions including the precuneus and RTPJ, and heightened precuneus connectivity with social and affective processing regions. These differences appear to be specific to sexual risk taking, as engagement in other health-risk behaviors and mere sexual intercourse experience did not explain the results. Activation in these regions has preliminarily been associated more broadly with adolescent risk-taking during social situations (Rodrigo et al., 2014); however, this is the first study to demonstrate heightened response of these socially relevant affective and reward processing circuits among adolescents who have engaged in risky sexual behavior specifically. The TPJ, rACC, vlPFC, and dorsal mPFC are most often implicated as part of the default mode network, a set of regions whose coordinated function is postulated to underlie self-referential, reward, and social cognitive processing (Amft et al., 2015). The temporoparietal junction—particularly the right TPJ—is involved in reorienting towards and processing socially-relevant information (Krall et al., 2015). The anterior insula and vlPFC are important regions for reward salience and affect regulation, respectively (Smith et al., 2014; Steinberg, 2008). Notably, ras pathway activation in these regions has been associated with broader risky decision making following peer evaluation (Falk et al., 2014; Peake et al., 2013). Dorsal mPFC and rACC have functional and structural connectivity with the ventral striatum (Haber et al., 2006; Haber and Knutson, 2010) and are thought to play a modulatory role in reward processing (Goto and Grace, 2008). Dorsomedial PFC is also putatively associated with both intrinsic reward and social processing (de la Vega et al., 2016). Thus, while heightened vs activation or functional connectivity with the precuneus was not observed specifically among higher sexual risk adolescents, the vs may still be playing a role in riskier sexual behavior through modulation of frontal regions. The observed functional coordination among social, reward, and affective-processing regions among higher sexual risk adolescents likely reflects a complex interplay among several factors. These could include adolescents’ individuals’ sexual experiences, tendencies toward interpersonal reward seeking and enjoyment, sensitivity to socially rewarding stimuli, and orientation toward social rewards. The use of the precuneus, a region implicated in autobiographical memory, self, and agency (Krall et al., 2015) as functional connectivity seed indicates that circuitry mediating self-relevant and social behavior is altered in adolescents who have had experiences more commonly associated with STIs and other adverse health outcomes (Ashenhurst et al., 2017). Whereas previous studies have focused on immature executive function as a key factor in adolescent risky sexual decision making and regional brain responsiveness (Ewing et al., 2015; Goldenberg et al., 2013), our results emphasize the contributing role of function in social and affective circuitry (Victor and Hariri, 2016). Indeed, experts from the fields of adolescent sexual health (e.g., Halpern, 2010) and developmental neuroscience (e.g., Victor and Hariri, 2016) have highlighted the need for research that considers both the social and biological contexts of adolescent sexual behavior. Adolescence is a developmental period marked by a notable increase in neural and biological sensitivity to social reward, which contributes to greater engagement in general risk-taking behaviors (Gardner and Steinberg, 2005; Knoll et al., 2015). Yet the intersecting social and biological influences on adolescent risk behavior may be especially relevant for sexual risk behavior.