Download Mothers and the Teen Brain: The Contribution of Maternal Presence

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.
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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.
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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
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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.
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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.
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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.
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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);
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