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Mothers and the Teen Brain: The Contribution of Maternal Presence on Neural Reward Processing and Decision Making during Adolescence João F. Guassi Moreira SURF 2015 Research Report My Research Interests: João is interested in the influence of close relationships on adolescent neural development and well-being. 1 Abstract Adolescent neural development is marked by heighted reward sensitivity and slow-to-develop cognitive control abilities, contributing to higher levels of risky decision making. However, recent research has demonstrated that the social context can affect the extent to which adolescents make risky decisions. Specifically, a mother’s presence alters the way in which teens process rewards, leading to safer decision making. Despite this, it remains unknown whether this is unique to maternal presence or generalizes to other authority figures. To answer this question, 23 adolescents underwent an fMRI scan, completing a risk-taking task in the presence of their mothers and again in the presence of an authority figure. Results suggest that the effect of maternal presence on adolescent risk-taking does not generalize to other authority figures, as evidenced by an increase in the rewarding nature of safe decisions and a decrease in the rewarding nature of risky decisions. 2 Introduction Adolescence is a time of heightened vulnerability to poor decision making which is thought to arise due to developmental changes in the brain (Nelson et al., 2005). Specifically, the adolescent brain undergoes a period of reorientation in which reward processing systems mature at an astonishing rate, characterized by a curvilinear pattern, whereas their cognitive control counterparts trudge along a path of protracted, linear development. This phenomenon engenders a subsequent inclination for risky behavior that leads to preventable instances of morbidity and mortality. In other words, the brain becomes increasingly sensitive to rewards and adolescents will go to great lengths to experience them. Yet the brain regions associated with self-control and impulse inhibition are still comparatively underdeveloped, leaving teens ill-equipped to make proper decisions. However, such lapses in decision making are not immutable among youth: different social contexts of adolescent decision making alter risky decisions and related neural processing. For instance, adolescents engage in more risk taking behavior in the presence of peers, which is associated with heightened ventral striatum (VS) activation (Chein et al., 2011), a brain region implicated in reward sensitivity and processing (Galvan et al., 2005). In contrast, adolescents are less likely to enact a risky decision when their mother is present compared to when they are alone, displaying reduced striatal activation in the presence of their mother (Telzer, et al., 2015). It remains unclear, however, whether the greater frequency of safe decision making and diminished neural reward sensitivity is specific to parental figures, or is due to their perceived role as authority figures and therefore would apply to any adult presence. I addressed this question this summer by analyzing data from 23 adolescent participants (Mage=15.22 years, SD=0.35, 13 European American) who completed two runs of a driving simulation during an fMRI scan. During one run, participants were told they were being watched 3 by their mother. During another, they were told they were being watched by an authority figure. This was counterbalanced to control for any effects of order. The authority figure was introduced as a professor who was an expert in adolescent driving behavior. Their mother or authority figure spoke into the microphone prior to the respective run, indicating they were watching the teen. During the scan participants encountered 26 yellow-light traffic signals and had a choice to go or stop. If participants chose to go, they ran the risk of crashing. Therefore, as in prior research (Chein et al., 2011; Telzer et al., 2015), and consistent with real world decisions when driving, go decisions were risky whereas stop decisions were safe. Tasks & Responsibilities My tasks this summer involved analyzing and interpreting data. Behavioral data, or participants’ decisions from the driving task alone, are relatively straightforward to analyze. In this case, of interest would be statistically significant differences between decisions in the presence of one’s mother, compared to an authority figure. Accordingly, I conducted a withinsample t-test examining decisions to stop, the results of which are noted in the next section. Brain imaging data, however, requires more involved analyses and several more steps. First, analyses must be conducted on each participant’s individual data to examine neural activation during stop decisions and go decisions. This allows us to understand what brain regions are active during a decision to go or stop for any given participant. Afterwards, it is necessary create contrasts for all comparisons of interest (e.g., go vs stop) and run these on each participant individually to determine what brain regions are active while going relative to stopping. Once these analyses were completed, I performed group level analyses which are aimed at revealing brain activation of interest among all 23 participants. 4 Results & Discussion Analysis of behavioral data revealed that participants tended to make fewer risky choices when their mother was present (M=43.59% of trials) compared to the authority figure (M=40.11% of trials), t(22)=1.58, p=0.065, one-tailed. At the neural level, I found that when making stop decisions, mother’s presence, compared to that of the authority figure, was related to heightened VS activity (t(22)=4.70, p<.005; xyz= 12, -1, 2; Figure 1a). Moreover, when successfully running through a yellow light, mother’s presence was associated with less activation in the VS (t(22)=3.27, p<.005; xyz= 6, 14, -5; Figure 1b). That the VS is involved in reward processing (Casey et al., 2008) suggests that maternal presence boosts the rewarding nature of being safe (i.e., stop decisions) and at the same time decreases the rewarding nature of being risky (i.e., go decisions). Importantly, these findings suggest that mothers uniquely serve a buffering role on teens’ risky behavior that does not generalize to other adult or authority figures. These results reinforce two scientifically supported conceptions of adolescents. First, while adolescents are indeed prone to risky decisions, this is not unavoidable. The results here, coupled with those from previous work (Telzer et al., 2015), demonstrate that the context in which adolescents make decisions greatly influences the likelihood that they will make safe choices. Second, despite what popular lay theories of adolescence may hold, teens and their parents still maintain meaningful relationships (Tsai et al., 2013). These results fit in with prior work demonstrating the unique and meaningful contribution of maternal presence on safe decision making. One interpretation of this is that parents don’t help their children make better decisions simply because of their roles as authority figures, but rather appear to do so because of their roles as caregivers and because adolescents indeed value teen-parent relationships. 5 Future Directions While these results are very exciting in their own right, more work needs to be conducted to fully explore the effect documented here. For instance, do self-reported levels of conflict or relationship quality with one’s parents attenuate the effect observed here? Additionally, by what neural mechanism could this effect be accounted for? Does this occur because adolescents are more easily able to take the perspective of their parents compared to a newly introduced authority figure? These questions will be the subject of my future work with these data. Finally, I am planning on submitting these results for presentation at a conference on adolescent research in the spring of 2016. My advisor and I also intend to draft our findings into a manuscript to be submitted for publication in a peer-reviewed journal. 6 Figure 1. Altered neural reward processing, as indexed by ventral striatal activity, during maternal presence compared to the presence of an authority figure. Note: Go – Pass refers to a successful attempt at running the yellow light (i.e., does not result in crashing); 7