Neurite density of the hippocampus is associated with trace eyeblink conditioning latency in 4- to 6-year-olds.

Limited options exist to evaluate the development of hippocampal function in young children. Research has established that trace eyeblink conditioning (EBC) relies on a functional hippocampus. Hence, we set out to investigate whether trace EBC is linked to hippocampal structure, potentially serving as a valuable indicator of hippocampal development. Our study explored potential associations between individual differences in hippocampal volume and neurite density with trace EBC performance in young children. We used onset latency of conditioned responses (CR) and percentage of conditioned responses (% CR) as measures of hippocampal-dependent associative learning. Using a sample of typically developing children aged 4 to 6 years (N = 30; 14 girls; M = 5.70 years), participants underwent T1- and diffusion-weighted MRI scans and completed a 15-min trace eyeblink conditioning task conducted outside the MRI. % CR and CR onset latency were calculated based on all trials involving tone-puff presentations and tone-alone trials. Findings revealed a connection between greater left hippocampal neurite density and delayed CR onset latency. Children with higher neurite density in the left hippocampus tended to blink closer to the onset of the unconditioned stimulus, indicating that structural variations in the hippocampus were associated with more precise timing of conditioned responses. No other relationships were observed between hippocampal volume, cerebellum volume or neurite density, hippocampal white matter connectivity and any EBC measures. Preliminary results suggest that trace EBC may serve as a straightforward yet innovative approach for studying hippocampal development in young children and populations with atypical development.

Childhood wayfinding experience explains sex and individual differences in adult wayfinding strategy and anxiety.

BACKGROUND: Anyone who has ever found themselves lost while driving in an unfamiliar neighborhood or forgotten where they parked their car can appreciate the importance of being able to navigate their environment. Navigation, or wayfinding, is a large-scale spatial ability that involves keeping track of the relative positions of objects and features in space, which allows for determining the path to a goal location. Early experiences shape spatial skill development, and research finds sex differences in spatial behaviors from preschool through adulthood, with males consistently outperforming females. The basis for sex differences in spatial aptitude is still debated, but explanations include differences in childhood spatial experience, the use of strategies for solving large-scale spatial problems, and spatial anxiety. The current study seeks to understand childhood wayfinding factors that may influence sex and individual differences in wayfinding strategies and wayfinding anxiety in adulthood. METHOD: One hundred fifty-nine undergraduate psychology students reported their childhood wayfinding experience (i.e., time spent outside, distance traveled), current use of wayfinding strategies (i.e., route strategy, orientation strategy), and current wayfinding anxiety and general anxiety levels. RESULTS: Independent samples t tests revealed that, compared with females, males reported spending more time outside and traveling farther distances as children, having less current wayfinding anxiety and route strategy use, and having more current orientation strategy use. Mediation analyses found that distance traveled, but not time spent outdoors, during childhood mediated sex differences in route strategy use and wayfinding anxiety in adults, even when controlling for general anxiety. Furthermore, when controlling for participant sex and general anxiety, current wayfinding anxiety mediated the relationship between distance traveled during childhood and route strategy use in adults. CONCLUSION: The current findings provide potential environmental explanations for sex and individual differences in large-scale spatial behaviors, including wayfinding. Specifically, sex differences in early wayfinding experience may explain why males and females develop different strategies for navigating and different levels of wayfinding anxiety. Furthermore, regardless of sex, allowing children to explore and navigate their outdoor environments away from home may help lessen their fears about navigating and, in turn, improve the strategies they choose to traverse unfamiliar territories.

Using hippocampal-dependent eyeblink conditioning to predict individual differences in spatial reorientation strategies in 3- to 6-year-olds.

The hippocampus is a subcortical structure in the medial temporal lobe involved in cognitive functions such as spatial navigation and reorientation, episodic memory, and associative learning. While much is understood about the role of hippocampal function in learning and memory in adults, less is known about the relations between the hippocampus and the development of these cognitive skills in young children due to the limitations of using standard methods (e.g., MRI) to examine brain structure and function in developing populations. This study used hippocampal-dependent trace eyeblink conditioning (EBC) as a feasible approach to examine individual differences in hippocampal functioning as they relate to spatial reorientation and episodic memory performance in young children. Three- to six-year-old children (N = 50) completed tasks that measured EBC, spatial reorientation, and episodic memory, as well as non-hippocampal-dependent processing speed abilities. Results revealed that when age was held constant, individual differences in EBC performance were significantly related to individual differences in performance on the spatial reorientation test, but not on the episodic memory or processing speed tests. When the relations between hippocampal-dependent EBC and different reorientation strategies were explored, it was found that individual differences in hippocampal function predicted the use of geometric information for reorienting in space as opposed to a combined strategy that uses both geometric information and salient visual cues. The utilization of eyeblink conditioning to examine hippocampal function in young populations and its implications for understanding the dissociation between spatial reorientation and episodic memory development are discussed.

Individual differences in non-clinical maternal depression impact infant affect and behavior during the still-face paradigm across the first year.

Maternal depression can significantly impact mothers' sensitivity to their infants' needs as well as infants' social and emotional development. The still-face paradigm (SFP) is widely used to assess infants' understanding of the contingency between their own behavior and that of their caregivers, as well as infants' ability to self-regulate arousal levels during sudden changes in maternal responsiveness. Infants of clinically depressed mothers display blunted levels of negative affect compared to infants of non-depressed mothers during the still-face (SF) phase. However, little is known about whether individual differences in elevated, non-clinical levels of maternal depression similarly affect mother-infant interactions. The current study examines the longitudinal effects of non-clinical maternal depression on infant and maternal behaviors during the SFP. Infants (N=63) were assessed at 5 and 9 months and maternal depression was assessed at 5 months using the Beck Depression Inventory (BDI). Infants of mothers with elevated levels of depression displayed less negative engagement during the SF phase compared to infants of mothers with lower levels of depression. This effect was present at 5 months, but not at 9 months. Findings demonstrate that non-clinical levels of maternal depressive symptomatology can have a significant impact on infants' affective regulation during the first half of the first year of life, but this does not necessarily have a long-lasting influence later in infancy. Interventions may want to target mothers with non-clinical depression to promote healthy infant social and emotional development.

A new biomarker to examine the role of hippocampal function in the development of spatial reorientation in children: a review.

Spatial navigation is an adaptive skill that involves determining the route to a particular goal or location, and then traveling that path. A major component of spatial navigation is spatial reorientation, or the ability to reestablish a sense of direction after being disoriented. The hippocampus is known to be critical for navigating, and has more recently been implicated in reorienting in adults, but relatively little is known about the development of the hippocampus in relation to these large-scale spatial abilities in children. It has been established that, compared to school-aged children, preschool children tend to perform poorly on certain spatial reorientation tasks, suggesting that their hippocampi may not be mature enough to process the demands of such a task. Currently, common techniques used to examine underlying brain activity, such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), are not suitable for examining hippocampal development in young children. In the present paper, we argue instead for the use of eyeblink conditioning (EBC), a relatively under-utilized, inexpensive, and safe method that is easy to implement in developing populations. In addition, EBC has a well defined neural circuitry, which includes the hippocampus, making it an ideal tool to indirectly measure hippocampal functioning in young children. In this review, we will evaluate the literature on EBC and its relation to hippocampal development, and discuss the possibility of using EBC as an objective measure of associative learning in relation to large-scale spatial skills. We support the use of EBC as a way to indirectly access hippocampal function in typical and atypical populations in order to characterize the neural substrates associated with the development of spatial reorientation abilities in early childhood. As such, EBC is a potential, simple biomarker for success in tasks that require the hippocampus, including spatial reorientation.