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Humans learn about their environments by observing others, including what to fear and what to trust. Observational fear learning may be especially important early in life when children turn to their parents to gather information about their world. Yet, the vast majority of empirical research on fear learning in youth has thus far focused on firsthand classical conditioning, which may fail to capture one of the primary means by which fears are acquired during development. To address this gap in the literature, the present study examined observational fear learning in youth (n = 33; age range: 6-17 years) as they watched videos of their parent and an "unfamiliar parent" (i.e., another participant's parent) undergo fear conditioning. Youth demonstrated stronger fear learning when observing their parent compared to an unfamiliar parent, as indicated by changes in their self-reported liking of the stimuli to which their parents were conditioned (CS+, a geometric shape paired with an aversive noise; CS-, a geometric shape never paired with an aversive noise) and amygdala responses. Parent trait anxiety was associated with youth learning better (i.e., reporting a stronger preference for the CS- relative to CS+), and exhibiting stronger medial prefrontal-amygdala connectivity. Neuroimaging data were additionally acquired from a subset of parents during firsthand conditioning, and parental amygdala and mPFC activation were associated with youth's neural recruitment. Together, these results suggest that youth preferentially learn fears via observation of their parents, and this learning is associated with emotional traits and neural recruitment in parents.

IntroductionResearch has highlighted relationships between the micro-organisms that inhabit our gastrointestinal tract (oral and gut microbiota) with host mood and gastrointestinal functioning. Mental health disorders and functional gastrointestinal disorders co-occur at high rates, although the mechanisms underlying these associations remain unclear. The Bugs and Brains Study aims to investigate complex relationships between anxiety/depression and irritable bowel syndrome (IBS) in two ways. First, its primary component will compare the gut and oral microbiota in females with anxiety/depression and/or IBS relative to controls, and investigate underlying physiological, endocrine and immune factors, as well as associations with diet and psychosocial factors. In an ancillary component, the study will also investigate gastrointestinal and mental health symptoms in a larger sample, and explore relationships with diet, exercise, oral health, substance use, medical history, early life adversity and psychosocial factors.Methods and analysisThe Bugs and Brains Study aims to recruit 160 females to the primary component: (1) 40 controls; (2) 40 participants with a depressive/anxiety disorder, but no IBS; (3) 40 participants with IBS, but no depressive/anxiety disorder and (4) 40 participants with both depressive/anxiety disorder and IBS. Participation is completed within 1 month, and involves comprehensive questionnaires, anthropometrics, a diagnostic clinical interview, collection of two saliva samples, and stool, urine and hair samples. This study aims to use a systems biology approach to characterise oral and gut microbial composition and function using 16S rRNA gene sequencing and nuclear MR spectroscopy. As part of the ancillary component, it will collect questionnaire data from 1000 participants aged 18-40 years, capturing mental health, gastrointestinal health, oral health, diet and psychosocial factors.Ethics and disseminationApproval was granted by the University of Melbourne Human Research Ethics Committee (#1749221). All participants voluntarily provided informed consent. Results will be published in peer-reviewed journals and presented at scientific conferences.

Episodic memory is critical to human functioning. In adults, episodic memory involves a distributed neural circuit in which the hippocampus plays a central role. As episodic memory abilities continue to develop across childhood and into adolescence, studying episodic memory maturation can provide insight into the development and construction of these hippocampal networks, and ultimately clues to their function in adulthood. While past developmental studies have shown that the hippocampus helps to support memory in middle childhood and adolescence, the extent to which ongoing maturation within the hippocampus contributes to developmental change in episodic memory abilities remains unclear. In contrast, slower maturing regions, such as the PFC, have been suggested to be the neurobiological locus of memory improvements into adolescence. However, it is also possible that the methods used to detect hippocampal development during middle childhood and adolescence are not sensitive enough. Here, we examine how temporal covariance (or differentiation) in voxel representations within anterior and posterior hippocampus change with age to support the development of detailed recollection in male and female developing humans. We find age-related increases in the distinctiveness of temporal activation profiles in the posterior, but not anterior, hippocampus. Second, we show that this measure of granularity, when present during postencoding rest periods, correlates with the recall of detailed memories of preceding stimuli several weeks postencoding, suggesting that granularity may promote memory stabilization.SIGNIFICANCE STATEMENT Studying hippocampal maturation can provide insight into episodic memory development, as well as clues to episodic functioning in adulthood. Past work has shown evidence both for and against hippocampal contributions to age-related improvements in memory performance, but has relied heavily on univariate approaches (averaging activity across hippocampal voxels), which may not be sensitive to nuanced developmental change. Here we use a novel approach, examining time signatures in individual hippocampal voxels to reveal regionally specific (anterior vs posterior hippocampus) differences in the distinctiveness (granularity) of temporal activation profiles across development. Importantly, posterior hippocampus granularity during windows of putative memory stabilization was associated with long-term memory specificity. This suggests that the posterior hippocampus gradually builds the capacity to support detailed episodic recall.

Is the microbiome a promising adjunct, a potential panacea, or a distraction from feasible treatments for neurodevelopmental disorders? Taking a developmental approach may get us closer to understanding the data and give us pause in trying to translate this nascent field to the clinic right now.

Parents' natural language when describing health-related threats reflects parents' cognitions that may shape their transmission of anxiety and fear. Parents' greater communal focus (i.e., higher we-talk) and less self-focus (i.e., lower I-talk) may buffer against intergenerational fear/anxiety transmission. The current study investigated whether the relation between parents' and children's anxiety and pandemic-related fear differed by parent we- and I-talk. Parents of 114 children (2–19 years; M = 9.75, SD = 3.73) completed online measures assessing children's and parents' anxiety and COVID-19-related fears, and engaged in a written reflection on their early pandemic experiences. The proportion of parents' we-talk and I-talk during the reflection was obtained using Linguistic Inquiry Word Count software. Results of multilevel structural equation models were partially consistent with expectations: The protective effect of we-talk was only observed for parents with lower fear/anxiety. For parents with higher fear/anxiety, higher I-talk was associated with lower child fear/anxiety. At higher levels of parent we-talk and at lower levels of I-talk, there was an unexpectedly positive association between parents' and children's fear/anxiety. The concordance between parents' and their children's fear/anxiety differs depending on parents' natural language when reflecting on the pandemic. [ABSTRACT FROM AUTHOR]

Unlike adult memories that can be remembered for many years, memories that are formed early in life are more fragile and susceptible to being forgotten (a phenomenon known as "infantile" or "childhood" amnesia). Nonetheless, decades of research in both humans and nonhuman animals demonstrate the importance of early life experiences on later physical, mental, and emotional functioning. This raises the question of how early memories can be so influential if they cannot be recalled. This review presents one potential solution to this paradox by considering what happens to an early memory after it has been forgotten. Specifically, we describe evidence showing that these forgotten early-acquired memories have not permanently decayed from storage. Instead, there appears to be a memory "trace" that persists in the face of forgetting which continues to affect a variety of behavioral responses later in life. Excitingly, the discovery of this physical trace will allow us to explore previously untestable issues in new ways, from whether forgetting is due to a failure in retrieval or storage to how memories can be recovered after extended periods of time. A greater understanding of the characteristics of this memory trace will provide novel insights into how some memories are left behind in childhood while others are carried with us, at least in some form, for a lifetime.