Conference Agenda

Spatial cognition and episodic memory are closely intertwined, sharing a common neural foundation in the entorhinal-hippocampal system. Beyond its well-established role in navigation and memory, recent research in adults suggests that spatial coding mechanisms within this system might serve as a neural and cognitive basis for concept formation and generalization. However, little is known about how this foundational function emerges during early development. How do spatial representations evolve to support not only navigation but also the structuring of knowledge? What role does the maturation of the entorhinal-hippocampal system play in shaping both memory and conceptual learning?

This symposium brings together five cutting-edge studies that investigate these developmental questions from infancy to early childhood using behavioral, neuroimaging, and electrophysiological approaches. The first talk presents longitudinal data on memory development in 4- to 8-year-olds, incorporating structural MRI to examine neuroanatomical changes. The second explores how 18- to 24-month-olds acquire and retain object-location-context associations, shedding light on early spatial learning mechanisms. The third highlights the role of neural oscillations in shaping memory and learning across development. The fourth study examines the relationship between spatial navigation abilities and early hippocampal and entorhinal development in one-year olds. Finally, the fifth talk investigates the relationship between spatial learning and memory formation in 4- to 8-year-olds.

By integrating findings across different ages and methodologies, this symposium advances our understanding of how spatial coding within the entorhinal-hippocampal system supports not only memory but also the broader cognitive structures essential for knowledge organization and concept formation.

The mature human memory system strikes a balance between the ability to remember specific details of past events and the capacity to detect regularities across these events for effective generalization to new situations. Transitioning to middle childhood, children’s memories become more detailed, as evidenced by an enhanced ability to differentiate among similar experiences (pattern separation) and to retrieve complete memories from partial information (pattern completion), while generalization skills continually advance as well. During the same period, the hippocampus –a brain region strongly implicated in memory-related processing– undergoes structural reorganization of its subfields, which have been differentially linked to the aforementioned memory components. There is cross-sectional evidence suggesting changes in these memory component functions from early to middle childhood. However, longitudinal data tracing their developmental trajectories and covariation while simultaneously assessing changes in neural substrates and mechanisms are currently lacking. The present study addresses this gap by using an accelerated longitudinal design, with three yearly measurements of children aged 4 to 8 years. Our comprehensive approach incorporates a variety of memory tasks testing the different memory components in multiple task settings, alongside structural magnetic resonance imaging (MRI) focussing on the hippocampus and diffusion-weighted MRI. The initial timepoint of the study has been completed with 174 participants. The second will be concluded in August 2025, and the third by June 2026. In this talk, preliminary cross-sectional findings revealing expected age differences in memory performance as well as an outlook on planned data analyses will be presented.

The second year of life marks a critical transition in episodic memory development, as memory shifts from being rather rigid and short-lived to more flexible and enduring episodic-like forms. This transition coincides with rapid hippocampal maturation and the offset of the infantile amnesia period, which is characterized by the absence of long-lasting episodic memories. However, the mechanisms enabling toddlers to start to form and retain enduring, episodic-like memories remain poorly understood.

In this study, we use mobile EEG to examine neural correlates of interindividual differences in how 18- to 20-month-old toddlers encode associative memories and retain them across delays of 1 day, 1 month, and 3 months. In an immersive real-world-like object-location-context association task, toddlers freely navigate their environment to encode and later retrieve memories, offering insights into episodic-like memory formation in a spatial learning context.

Preliminary findings from n = 101 toddlers reveal substantial variability in learning and retention, highlighting interindividual differences in the formation and stability of early memory representations. By identifying key predictors of successful memory formation and retention, this research will provide novel insights into how spatial learning mechanisms may support emerging episodic memory in early childhood. More broadly, this study advances our understanding of how foundational memory skills in toddlers evolve and stabilize over time, potentially forming the basis for learning and memory later in life.

Despite growing interest, the neural rhythms of the developing brain remain poorly understood. The adult visual system is dominated by oscillations in the 3–8 Hz theta and 8–14 Hz alpha ranges. Here, we present two studies that look at the development of these two fundamental operating frequencies from infancy into adulthood.

In the first study, we explored resonance phenomena and operating frequencies in the infant visual system using rhythmic visual stimulation. We found that the infant brain responded at the 4Hz theta rhythm following visual stimulation at various frequencies (2-30Hz). Moreover, presenting random flicker sequences elicited a perceptual echo that repeated at 4 Hz. In contrast, the adult visual system exhibited resonance and perceptual echoes in the alpha range.

Second, we investigated the functional properties of theta and alpha rhythms in infants aged six and twelve months, children at four and six years and adults using time-frequency and functional connectivity analyses. Preliminary results from infants indicate that theta increases over the first trials and the reduces over multiple presentations, while connectivity increases globally for novel compared to familiar images, suggesting a crucial role of theta in the formation of novel representations.

Collectively, these findings underscore the importance of the theta rhythm in early childhood development. Results will be discussed within the framework of two concurrent perspectives.

During their first year, infants rapidly acquire motor skills—from sitting, to crawling, and eventually walking. This progression has been linked to emerging cognitive abilities, particularly spatial perception. Clearfield (2004) found that infants who can walk (~12 months) performed better in spatial search tasks than crawlers. Regarding the underlying neurodevelopment, Marrus et al., (2018) showed that stronger sensorimotor connectivity correlates with the onset of walking. However, the neural basis of spatial cognition at this developmental stage remains underexplored.
The present study investigates two aspects of early motor development. First, we analyze the developmental trajectory of the infant brain, focusing on motor cortical and medio-temporal maturation from birth to 24 months. Using 891 anatomical images from the Baby Connectome Project, we establish normative trajectories that serve as a reference for interpreting locally collected MRI data, in critical brain regions for motor development: premotor area, primary motor cortex, supplementary motor areas, hippocampus and entorhinal cortex, integrated into a maturity metric.
Second, we examine how infants’ motor abilities at 12 months (n=30) influence spatial navigation skills, and how this would be mediated by our neurodevelopmental metric of the infant motor system. Initial findings, based on region volumes, indicate that motor skills positively correlated with spatial navigation abilities (r(46)=0.30, p<.05), relative voxel size of motor regions (r(29)=0.39, p<.05) and hippocampal formation (r(29)=0.38, p<.05). Leveraging big data towards an age adjusted neurodevelopmental metric, will provide an important step in our developing understanding of the neural underpinnings of motor and hippocampal development and their effect on spatial cognition.

Grid cells in the entorhinal cortex provide structured scaffolds for spatial, visual, episodic, and conceptual representations. Reports of macroscopic grid-like codes in adolescence suggest a prolonged functional maturation of the entorhinal cortex from middle childhood to young adulthood. However, children typically reach adult-like performance in spatial tasks before age 12. To examine whether the emergence of entorhinal grid-like codes supports the development of navigation ability and memory in early childhood, we will collect fMRI data from 6- to 8-year-old children conducting an object location memory task. The sample will be sourced from an ongoing longitudinal study on memory development, providing comprehensive structural MRI data and behavioral memory phenotyping. Entorhinal grid-like codes will be identified as the hexadirectional modulation of the BOLD signal of walking directions, and the magnitude of the modulation will serve as an indicator of the functional maturation of the entorhinal cortex. By integrating the macroscopic grid-code proxy with existing longitudinal data, we will examine the relations between the maturation of hippocampal structure, cognition, and functional entorhinal cortex development.