Effects of stress on 6- and 7-year-old children's emotional memory differs by gender.

Understanding effects of emotional valence and stress on children's memory is important for educational and legal contexts. This study disentangled the effects of emotional content of to-be-remembered information (i.e., items differing in emotional valence and arousal), stress exposure, and associated cortisol secretion on children's memory. We also examined whether girls' memory is more affected by stress induction. A total of 143 6- and 7-year-old children were randomly allocated to the Trier Social Stress Test for Children (n = 103) or a control condition (n = 40). At 25 min after stressor onset, children incidentally encoded 75 objects varying in emotional valence (crossed with arousal) together with neutral scene backgrounds. We found that response bias corrected memory was worse for low-arousing negative items than for neutral and positive items, with the latter two categories not being different from each other. Whereas boys' memory was largely unaffected by stress, girls in the stress condition showed worse memory for negative items, especially the low-arousing ones, than girls in the control condition. Girls, compared with boys, reported higher subjective stress increases following stress exposure and had higher cortisol stress responses. Whereas a higher cortisol stress response was associated with better emotional memory in girls in the stress condition, boys' memory was not associated with their cortisol secretion. Taken together, our study suggests that 6- and 7-year-old children, more so girls, show memory suppression for negative information. Girls' memory for negative information, compared with that of boys, is also more strongly modulated by stress experience and the associated cortisol response.

Hippocampus and striatum show distinct contributions to longitudinal changes in value-based learning in middle childhood.

The hippocampal-dependent memory system and striatal-dependent memory system modulate reinforcement learning depending on feedback timing in adults, but their contributions during development remain unclear. In a 2-year longitudinal study, 6-to-7-year-old children performed a reinforcement learning task in which they received feedback immediately or with a short delay following their response. Children's learning was found to be sensitive to feedback timing modulations in their reaction time and inverse temperature parameter, which quantifies value-guided decision-making. They showed longitudinal improvements towards more optimal value-based learning, and their hippocampal volume showed protracted maturation. Better delayed model-derived learning covaried with larger hippocampal volume longitudinally, in line with the adult literature. In contrast, a larger striatal volume in children was associated with both better immediate and delayed model-derived learning longitudinally. These findings show, for the first time, an early hippocampal contribution to the dynamic development of reinforcement learning in middle childhood, with neurally less differentiated and more cooperative memory systems than in adults.

Stable longitudinal associations of family income with children's hippocampal volume and memory persist after controlling for polygenic scores of educational attainment.

Despite common notion that the correlation of socioeconomic status with child cognitive performance may be driven by both environmentally- and genetically-mediated transactional pathways, there is a lack of longitudinal and genetically informed research that examines these postulated associations. The present study addresses whether family income predicts associative memory growth and hippocampal development in middle childhood and tests whether these associations persist when controlling for DNA-based polygenic scores of educational attainment. Participants were 142 6-to-7-year-old children, of which 127 returned when they were 8-to-9 years old. Longitudinal analyses indicated that the association of family income with children's memory performance and hippocampal volume remained stable over this age range and did not predict change. On average, children from economically disadvantaged background showed lower memory performance and had a smaller hippocampal volume. There was no evidence to suggest that differences in memory performance were mediated by differences in hippocampal volume. Further exploratory results suggested that the relationship of income with hippocampal volume and memory in middle childhood is not primarily driven by genetic variance captured by polygenic scores of educational attainment, despite the fact that polygenic scores significantly predicted family income.

Mood repair in healthy individuals: Both processing mode and imagery content matter.

BACKGROUND: The recall of positive autobiographical memories (mood repair) is an effective strategy for improving sad mood. In depressed individuals mood repair has shown to be most effective, if the memory was processed in a concrete (imaginable), as opposed to an abstract (verbal) processing mode. However, it is not yet clear whether this also applies to healthy subjects. Moreover we do not know whether intensity and content of an imagery stimulus influences its effectiveness. We report on two experimental studies in healthy participants. METHODS: Negative emotion induction was followed by mood repair via recall of positive autobiographical memories. In study I, abstract processing was compared to two concrete processing strategies (high concrete/low concrete). In study II, the content of the memories was systematically varied (social/achievement). RESULTS: In study I, a concrete processing resulted in better mood repair, however no differences were found between high and low concrete processing. In study II, both types of memories had comparable effects on mood repair but promoted different emotions. LIMITATIONS: Only a young, healthy, predominantly female population was investigated. CONCLUSIONS: Adopting a concrete processing mode when recalling positive memories leads to better mood repair in healthy participants. Moreover, the content of the memory determines the corresponding emotions.