Abstract: Although there is a long history of studying the influence of pubertal hormones on brain function/structure in animals, this research in human adolescents is young but burgeoning. Here, we provide a comprehensive review of findings from neuroimaging studies investigating the relation between pubertal and functional brain development in humans. We quantified the findings from this literature in which statistics required for standard meta-analyses are often not provided (i.e., effect size in fMRI studies). To do so, we assessed convergence in findings within content domains (reward, facial emotion, social information, cognitive processing) in terms of the locus and directionality (i.e., positive/negative) of effects. Face processing is the only domain with convergence in the locus of effects in the amygdala. Social information processing is the only domain with convergence of positive effects; however, these effects are not consistently present in any brain region. There is no convergence of effects in either the reward or cognitive processing domains. This limited convergence in findings across domains is not the result of null findings or even due to the variety of experimental paradigms researchers employ. Instead, there are critical theoretical, methodological, and analytical issues that must be addressed in order to move the field forward.
6. Conclusion
Although
there is a long history of studying the influence of pubertal hormones
on brain function and structure in animal models (see Sisk and Zehr, 2005a, 2005b),
similar research in human adolescents is still early in its own
ontogeny. We reviewed the existing 28 studies in this field that have
been primarily conducted in the last decade. To quantify the findings,
we measured convergence in results within content domains (reward,
facial emotion, social information, cognitive processing) in terms of
the locus and directionality of effects. We report that facial emotion
processing is the only content domain with convergence in the locus of
effects, such that studies consistently find a relation between metrics
of pubertal development and neural activation in the amygdala. Social
information processing is the only content domain in which there is
consistency across studies in the directionality of effects.
Specifically, functional brain activation during a variety of social
information tasks is consistently positively associated with measures of
pubertal development in adolescents; however, these effects do not
converge in any particular locus of the brain. In contrast, there is no
convergence in the locus or directionality of effects in either the
reward or cognitive processing domains. These findings highlight
important directions for scientists to pursue in future research.
Importantly,
we reveal that this limited convergence in findings relating functional
brain and pubertal development is not because of null findings or even
the variety of experimental paradigms researchers employ. For example,
in the social information processing domain, there is immense variety in
paradigm, but convergence in the directionality of effects. In
contrast, in the reward processing domain, there is high consistency in
the experimental paradigm, and participant sample across studies, but no
convergence in locus or directionality of effects. As a result, we
argue that there are critical theoretical, methodological, and analytic
issues that must be addressed in order to move the field forward. To
tackle these issues, we suggest that this interdisciplinary work needs
to be conducted by teams of scientists with complementary expertise in
adolescent development, pubertal development, endocrinology, and
pediatric neuroimaging.
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