Professor Wilbrecht’s essay, Your Twelve-Year-Old Isn’t Just Sprouting New Hair but Is Also Forming (and Being Formed by) New Neural Connections, appears in Think Tank: Forty Neuroscientists Explore the Biological Roots of Human Experience (David J. Linden, ed. 2018).
Undergraduate awards: Ben Hoshal won an MCB poster award and Nana Okada won a Psychology poster award. Congratulations to Ben and Nana!
This review summarizes the case for investing in adolescence as a period of rapid growth, learning, adaptation, and formational neurobiological development. Adolescence is a dynamic maturational period during which young lives can pivot rapidly—in both negative and positive directions. Scientific progress in understanding adolescent development provides actionable insights into windows of opportunity during which policies can have a positive impact on developmental trajectories relating to health, education, and social and economic success. Given current global changes and challenges that affect adolescents, there is a compelling need to leverage these advances in developmental science to inform strategic investments in adolescent health.
Ronald E. Dahl, Nicholas B. Allen, Linda Wilbrecht & Ahna Ballonoff Suleiman, Importance of investing in adolescence from a developmental science perspective, Nature (v 554) pp. 441–450 (Feb. 2018), doi:10.1038/nature25770
Wan Chen Lin passed her qualifying exam! Congratulations Wan Chen!
Age, sex, and gonadal hormones differently influence anxiety- and depression-related behavior during puberty in mice
Anxiety and depression symptoms increase dramatically during adolescence, with girls showing a steeper increase than boys after puberty onset. The timing of the onset of this sex bias led us to hypothesize that ovarian hormones contribute to depression and anxiety during puberty. In humans, it is difficult to disentangle direct effects of gonadal hormones from social and environmental factors that interact with pubertal development to influence mental health. To test the role of gonadal hormones in anxiety- and depression-related behavior during puberty, we manipulated gonadal hormones in mice while controlling social and environmental factors. Similar to humans, we find that mice show an increase in depression-related behavior from pre-pubertal to late-pubertal ages, but this increase is not dependent on gonadal hormones and does not differ between sexes. Anxiety-related behavior, however, is more complex at puberty, with differences that depend on sex, age, behavioral test, and hormonal status. Briefly, males castrated before puberty show greater anxiety-related behavior during late puberty compared to intact males, while pubertal females are unaffected by ovariectomy or hormone injections in all assays except the marble burying test. Despite this sex-specific effect of pubertal hormones on anxiety-related behavior, we find no sex differences in intact young adults, suggesting that males and females use separate mechanisms to converge on a similar behavioral phenotype. Our results are consistent with anxiolytic effects of testicular hormones during puberty in males but are not consistent with a causal role for ovarian hormones in increasing anxiety- and depression-related behavior during puberty in females.
Josiah R. Boivin, David J. Piekarski, Jessica K. Wahlberg, Linda Wilbrecht, Age, sex, and gonadal hormones differently influence anxiety- and depression-related behavior during puberty in mice, Psychoneuroendocrinology (available online 12 August 2017), https://doi.org/10.1016/j.psyneuen.2017.08.009
Ovarian Hormones Organize the Maturation of Inhibitory Neurotransmission in the Frontal Cortex at Puberty Onset in Female Mice
The frontal cortex matures late in development, showing dramatic changes after puberty onset, yet few experiments have directly tested the role of pubertal hormones in cortical maturation. One mechanism thought to play a primary role in regulating the maturation of the neocortex is an increase in inhibitory neurotransmission, which alters the balance of excitation and inhibition. We hypothesized that pubertal hormones could regulate maturation of the frontal cortex by this mechanism. Here, we report that manipulations of gonadal hormones do significantly alter the maturation of inhibitory neurotransmission in the cingulate region of the mouse medial frontal cortex, an associative region that matures during the pubertal transition and is implicated in decision making, learning, and psychopathology. We find that inhibitory neurotransmission, but not excitatory neurotransmission, increases onto cingulate pyramidal neurons during peri-pubertal development and that this increase can be blocked by pre-pubertal, but not post-pubertal, gonadectomy. We next used pre-pubertal hormone treatment to model early puberty onset, a phenomenon increasingly observed in girls living in developed nations. We find that pre-pubertal hormone treatment drives an early increase in inhibitory neurotransmission in the frontal cortex, but not the somatosensory cortex, suggesting that earlier puberty can advance cortical maturation in a regionally specific manner. Pre-pubertal hormone treatment also accelerates maturation of tonic inhibition and performance in a frontal-cortex-dependent reversal-learning task. These data provide rare evidence of enduring, organizational effects of ovarian hormones at puberty and provide a potential mechanism by which gonadal hormones could regulate the maturation of the associative neocortex.
David J. Piekarski, Josiah R. Boivin, Linda Wilbrecht, Ovarian Hormones Organize the Maturation of Inhibitory Neurotransmission in the Frontal Cortex at Puberty Onset in Female Mice, 27(12) Current Biology p1735–1745.e3, June 19, 2017.