Biology subjects

Varga, N. L.

Publications and source records attributed to Varga, N. L..

3 recordsLinked to original sources

bioRxiv2026

Hippocampal representations of temporal structure increase in scale and symmetry across development

Learning which experiences reliably co-occur in time is fundamental to episodic memory and improves markedly across childhood and adolescence. Although children and adults both engage the hippocampus while learning predictable sequences, the nature of the neural representations supporting statistical learning across development remains unknown. Here, we directly quantified item-level neural representations before and after children, early adolescents, and adults learned predictable temporal relationships between items, providing a direct measure of learning-related representational change. We identified three developmental shifts in hippocampal representation. First, although posterior hippocampus integrated temporally adjacent sequence elements similarly across age groups, integration of non-adjacent sequence elements increased with age in anterior hippocampus, indicating developmental expansion in the temporal scale of neural integration. Second, hippocampal representations changed in their directional organization, with children showing hippocampal representations reflecting only forward associations between adjacent events, whereas adolescents and adults exhibited bidirectional integration of sequence relationships. Third, functional connectivity between anterior hippocampus and frontoparietal cortex tracked statistical transition probabilities during learning and predicted memory performance. Together, these findings show that improvements in statistical learning during development reflect reorganization of hippocampal representations and hippocampal-cortical interactions, revealing how the developing brain constructs increasingly flexible representations of predictive temporal structure. HighlightsO_LIHippocampal representations of temporal sequences reorganize across development C_LIO_LITemporal integration expands from adjacent to non-adjacent events with age C_LIO_LISequence representations shift from forward-only to bidirectional integration C_LIO_LIHippocampal-frontoparietal connectivity predicts statistical learning ability C_LI

neuroscience↗

bioRxiv2025

Development of anterior hippocampal integration underlies the protracted emergence of cognitive map formation and generalization

Flexible memory depends on cognitive maps that integrate spatial relationships and guide behavior as environments change. The anterior hippocampus is well positioned to support integration across broad spatiotemporal scales, but its late maturation may constrain development of flexible, map-based navigation. Here, we tested whether hippocampal temporal autocorrelation, an index of neural activity stability over time, tracks the development of spatial integration. In a large resting-state fMRI sample (N = 382; ages 5-34 years), temporal autocorrelation increased with age in anterior, but not posterior, hippocampus. This anterior-specific pattern was replicated in an independent task-based fMRI sample of children, adolescents, and adults (N = 85; aged 6-12 years and adults), wherein we linked hippocampal autocorrelation to dissociable components of spatial behavior. The navigation task separated memory for object locations from the ability to update and generalize knowledge across rotations of the distal reference frame and to new object sets. Although all age groups learned object locations, only older participants showed evidence that prior spatial structure supported performance as the environment changed across runs. Critically, hippocampal autocorrelation related to behavior only when spatial knowledge was used across runs, rather than improved through within-run feedback, with the clearest profile emerging in adults. In adults, anterior and posterior autocorrelation jointly predicted precise object-location memory, whereas anterior autocorrelation uniquely predicted efficient trajectories from novel starting positions. These findings identify anterior hippocampal temporal autocorrelation as a later-maturing computation that supports the transition from local spatial learning in childhood to flexible navigation through changing environments in adulthood. Significance StatementFinding our way through the world requires more than remembering where things are. We also need to use what we have learned to take new routes, adjust when familiar places change, and apply old knowledge to new situations. These abilities improve from childhood to adulthood, but the brain changes that support this transition remain unclear. We show that a signal in anterior hippocampus, a brain region important for linking experiences, becomes more stable over development. Using a navigation task that separated remembering object locations from flexibly using a map, we found that this signal was most strongly tied to adults ability to navigate efficiently through changing environments. These findings reveal a hippocampal mechanism that supports flexible navigation as children mature.

neuroscience↗

bioRxiv2023

Differentiation of related events in hippocampus supports memory reinstatement in development

Adults are capable of either differentiating or integrating similar events in memory based on which representations are optimal for a given situation. Yet how children represent related memories remains unknown. Here, children (7-10 years) and adults formed memories for separate yet overlapping events. We then measured how successfully remembered events were represented and reinstated using functional magnetic resonance imaging (fMRI). We found that children formed differentiated representations in hippocampus--such that related events were stored as less similar to one another compared to unrelated events. Conversely, adults formed integrated representations, wherein related events were stored as more similar, including in medial prefrontal cortex (mPFC). Furthermore, hippocampal differentiation among children and mPFC integration among adults tracked neocortical reinstatement of the specific features associated with the individual events. Together, these findings reveal that the same memory behaviors are supported by different underlying representations across development. Specifically, whereas differentiation underlies memory organization and retrieval in childhood, integration exhibits a protracted developmental trajectory.

neuroscience↗