Adolescent neural response to reward is related to participant sex and task motivation

Abstract

Risky decision making is prominent during adolescence, perhaps contributed to by heightened sensation seeking and ongoing maturation of reward and dopamine systems in the brain, which are, in part, modulated by sex hormones. In this study, we examined sex differences in the neural substrates of reward sensitivity during a risky decision-making task and hypothesized that compared with girls, boys would show heightened brain activation in reward-relevant regions, particularly the nucleus accumbens, during reward receipt. Further, we hypothesized that testosterone and estradiol levels would mediate this sex difference. Moreover, we predicted boys would make more risky choices on the task. While boys showed increased nucleus accumbens blood oxygen level-dependent (BOLD) response relative to girls, sex hormones did not mediate this effect. As predicted, boys made a higher percentage of risky decisions during the task. Interestingly, boys also self-reported more motivation to perform well and earn money on the task, while girls self-reported higher state anxiety prior to the scan session. Motivation to earn money partially mediated the effect of sex on nucleus accumbens activity during reward. Previous research shows that increased motivation and salience of reinforcers is linked with more robust striatal BOLD response, therefore psychosocial factors, in addition to sex, may play an important role in reward sensitivity. Elucidating neurobiological mechanisms that support adolescent sex differences in risky decision making has important implications for understanding individual differences that lead to advantageous and adverse behaviors that affect health outcomes.

Sex differences in the neural underpinnings of social and monetary incentive processing during adolescence

“…The relatively reduced neural reactivity of boys to punishment fits well with our finding of their slightly lowered BIS scores compared with girls, indicating a somewhat reduced tendency toward punishment-related behaviors often seen in boys (see Paglaccio et al, 2016, for similar results). On the other hand, the relatively enhanced brain reactivity to rewards in adolescent boys is consistent with findings from a recent fMRI study showing a hyperactivation of reward-related brain regions (including the nucleus accumbens) in male adolescents for monetary rewards (Alarcon, Cservenka, & Nagel, 2017). Furthermore, it fits with findings on a later maturation of the medial prefrontal cortex in adolescent boys compared with their female counterparts.…”

“…The medial prefrontal cortex forms a major part of the mesocorticolimbic dopaminergic pathway, which regulates the incentive salience of rewards through the release of dopamine into the nucleus accumbens (Berridge & Kringelbach, 2015;Walker et al, 2017). Adolescent boys might attribute more salience to rewards because of the less mature mesocorticolimbic dopaminergic pathway and might thus be more prone to engage in risky behaviors to achieve these rewards (Alarcon et al, 2017;Walker et al, 2017).…”

Investigation of sex differences in delusion-associated cognitive biases

“…Thus, at this point, it is uncertain if the observed (small) sex differences in cognitive biases are specific to their delusion-associated aspects. Rather, they may be reflective of general differences between men and women in decision making, which have associated with a number of diverse factors such as self-confidence (Cross et al, 2017), sensitivity to short-term loss/punishment (Alarcón et al, 2017;Ding et al, 2017;van den Bos et al, 2013) or influence by stress (Kluen et al, 2017), and implicate both emotional and cognitive control systems (van den Bos et al, 2013). Further studies in larger samples are warranted to ascertain the presence of subtle sex differences in delusion-associated cognitive biases, and their exact nature.…”

Development of Multifaceted Risk Taking and the Relations to Sex Steroid Hormones: A Longitudinal Study

“…Another line of research used self‐report measurements, which are thought to provide sensitive measures of general tendencies of individuals to show certain types of behavior. These self‐report measures showed gradual age‐related declines in impulsivity, whereas self‐reported sensation seeking and reward drive peaked in mid‐adolescence (Steinberg et al.,), although this was not confirmed by all studies (Alarcon, Cservenka, & Nagel, ; Braams et al., ). Taken together, it remains unclear for which risk‐related processes—captured either by self‐report or task‐related measures—an adolescent rise in risk taking is observed (Defoe et al., ).…”