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The study of brain development and that of behavioral development have historically proceeded independently of one another. This is an unfortunate set of circumstances, given that the disciplines concerned with development—for example, developmental psychology, pediatrics, psychiatry, clinical psychology, and the neurosciences—have much to learn from each other. Drawing on recent advances in the developmental brain and behavioral sciences, we illustrate the transdisciplinary approach our group has adopted in the service of uniting the research on brain and behavior in the context of development. We specifically report on our nonhuman primate and human studies that collectively illustrate our “genes to behavior” approach to the study of development. Our goal in summarizing our research in this fashion is to promote discussion about promising templates for how research on brain, behavior, and development might proceed into the 21st century.

In the real world, many relationships between events are uncertain and probabilistic. Uncertainty is also likely to be a more common feature of daily experience for youth because they have less experience to draw from than adults. Some studies suggest probabilistic learning may be inefficient in youths compared to adults, while others suggest it may be more efficient in youths in mid adolescence. Here we used a probabilistic reinforcement learning task to test how youth age 8-17 (N = 187) and adults age 18-30 (N = 110) learn about stable probabilistic contingencies. Performance increased with age through early-twenties, then stabilized. Using hierarchical Bayesian methods to fit computational reinforcement learning models, we show that all participants’ performance was better explained by models in which negative outcomes had minimal to no impact on learning. The performance increase over age was driven by 1) an increase in learning rate (i.e. decrease in integration time scale); 2) a decrease in noisy/exploratory choices. In mid-adolescence age 13-15, salivary testosterone and learning rate were positively related. We discuss our findings in the context of other studies and hypotheses about adolescent brain development.

Large differences in COVID‐19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage were associated with low death rates in European countries. SARS‐CoV‐2 binds to its receptor, the angiotensin converting enzyme 2 (ACE2). As a result of SARS‐Cov‐2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT 1 R) axis associated with oxidative stress. This leads to insulin resistanceas well as lung and endothelial damage, two severe outcomes of COVID‐19. The nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2) is the most potent antioxidant in humans and can block the AT 1 R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are given: Kimchi in Korea, westernized foods and the slum paradox. It is proposed that fermented cabbage is a proof‐of‐concept of dietary manipulations that may enhance Nrf2‐associated antioxidant effects helpful in mitigating COVID‐19 severity.

the collection, analysis, and interpretation of data or in writing the manuscript, apart from their financial contribution; the content is solely the responsibility of the authors and does not necessarily represent the official views of any of the funding agencies. We would like to thank Claire Chie for her assistance in reliability coding and all participants and their families for their involvement in the study.

Global COVID‐19 lockdowns have disrupted adolescents’ in‐person social networks, increasing likelihood of loneliness. Social media can help adolescents maintain and develop peer relationships across distance. In this short longitudinal study with 735 Peruvian adolescents (ages: 11–17) from low‐to‐middle‐income urban settings, we investigated whether online experiences relate to loneliness during initial stages of lockdown. Loneliness remained constant between week 6 and 11 of lockdown, was higher for females and similar across school‐grades. Positive and negative online experiences were more frequent for older students, and females experienced more negative online experiences than males. Greater positive online experiences related to lower loneliness, with the reverse pattern for negative online experiences. Our results suggest that positive online experiences may mitigate loneliness during physical isolation.

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Multiple neurocognitive systems contribute simultaneously to learning. For example, dopamine and basal ganglia (BG) systems are thought to support reinforcement learning (RL) by incrementally updating the value of choices, while the prefrontal cortex (PFC) contributes different computations, such as actively maintaining precise information in working memory (WM). It is commonly thought that WM and PFC show more protracted development than RL and BG systems, yet their contributions are rarely assessed in tandem. Here, we used a simple learning task to test how RL and WM contribute to changes in learning across adolescence. We tested 187 subjects ages 8 to 17 and 53 adults (25-30). Participants learned stimulus-action associations from feedback; the learning load was varied to be within or exceed WM capacity. Participants age 8-12 learned slower than participants age 13-17, and were more sensitive to load. We used computational modeling to estimate subjects' use of WM and RL processes. Surprisingly, we found more robust changes in RL than WM during development. RL learning rate increased significantly with age across adolescence and WM parameters showed more subtle changes, many of them early in adolescence. These results underscore the importance of changes in RL processes for the developmental science of learning. Key words (max 6): development, reinforcement learning, working memory, computational modeling, adolescence to this research: boys girlsshould aim to develop experimental paradigms and computational models that more precisely dissociate the use of reinforcement learning, working memory, and episodic memory throughout development.