Age- and performance-related differences in hippocampal contributions to episodic retrieval

ObScene database: Semantic congruency norms for 898 pairs of object-scene pictures

Research on the interaction between object and scene processing has a long history in the fields of perception and visual memory. Most databases have established norms for pictures where the object is embedded in the scene. In this study, we provide a diverse and controlled stimulus set comprising real-world pictures of 375 objects (e.g., suitcase), 245 scenes (e.g., airport), and 898 object-scene pairs (e.g., suitcase-airport), with object and scene presented separately. Our goal was twofold. First, to create a database of object and scene pictures, normed for the same variables to have comparable measures for both types of pictures. Second, to acquire normative data for the semantic relationships between objects and scenes presented separately, which offers more flexibility in the use of the pictures and allows disentangling the processing of the object and its context (the scene). Along three experiments, participants evaluated each object or scene picture on name agreement, familiarity, and visual complexity, and rated object-scene pairs on semantic congruency. A total of 125 septuplets of one scene and six objects (three congruent, three incongruent), and 120 triplets of one object and two scenes (in congruent and incongruent pairings) were built. In future studies, these objects and scenes can be used separately or combined, while controlling for their key features. Additionally, as object-scene pairs received semantic congruency ratings along the entire scale, researchers may select among a wide range of congruency values. ObScene is a comprehensive and ecologically valid database, useful for psychology and neuroscience studies of visual object and scene processing.

A meta-analysis of the relation between hippocampal volume and memory ability in typically developing children and adolescents

Memory is supported by a network of brain regions, with the hippocampus serving a critical role in this cognitive process. Previous meta-analyses on the association between hippocampal structure and memory have largely focused on adults. Multiple studies have since suggested that hippocampal volume is related to memory performance in children and adolescents; however, the strength and direction of this relation varies across reports, and thus, remains unclear. To further understand this brain-behavior relation, we conducted a meta-analysis to investigate the association between hippocampal volume (assessed as total volume) and memory during typical development. Across 25 studies and 61 memory outcomes with 1357 participants, results showed a small, but significant, positive association between total hippocampal volume and memory performance. Estimates of the variability across studies in the relation between total volume and memory were not explained by differences in memory task type (delayed vs. immediate; relational vs. nonrelational), participant age range, or the method of normalization of hippocampal volumes. Overall, findings suggest that larger total hippocampal volume relates to better memory performance in children and adolescents and that this relation is similar across the memory types and age ranges assessed. To facilitate enhanced generalization across studies in the future, we discuss considerations for the field moving forward.

Developmental differences in memory reactivation relate to encoding and inference in the human brain

Despite the fact that children can draw on their memories to make novel inferences, it is unknown whether they do so through the same neural mechanisms as adults. We measured memory reinstatement as participants aged 7-30 years learned new, related information. While adults brought memories to mind throughout learning, adolescents did so only transiently, and children not at all. Analysis of trial-wise variability in reactivation showed that discrepant neural mechanisms-and in particular, what we interpret as suppression of interfering memories during learning in early adolescence-are nevertheless beneficial for later inference at each developmental stage. These results suggest that while adults build integrated memories well-suited to informing inference directly, children and adolescents instead must rely on separate memories to be individually referenced at the time of inference decisions.

How does episodic memory develop in adolescence?

Key areas of the episodic memory (EM) network demonstrate changing structure and volume during adolescence. EM is multifaceted and yet studies of EM thus far have largely examined single components, used different methods and have unsurprisingly yielded inconsistent results. The Treasure Hunt task is a single paradigm that allows parallel investigation of memory content, associative structure, and the impact of different retrieval support. Combining the cognitive and neurobiological accounts, we hypothesized that some elements of EM performance may decline in late adolescence owing to considerable restructuring of the hippocampus at this time. Using the Treasure Hunt task, we examined EM performance in 80 participants aged 10–17 yr. Results demonstrated a cubic trajectory with youngest and oldest participants performing worst. This was emphasized in associative memory, which aligns well with existing literature indicating hippocampal restructuring in later adolescence. It is proposed that memory development may follow a nonlinear path as children approach adulthood, but that future work is required to confirm and extend the trends demonstrated in this study.

Age-Related Increases in Posterior Hippocampal Granularity Are Associated with Remote Detailed Episodic Memory in Development

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.

How Behavior Shapes the Brain and the Brain Shapes Behavior: Insights from Memory Development

Source memory improves substantially during childhood. This improvement is thought to be closely related to hippocampal maturation. As previous studies have mainly used cross-sectional designs to assess relations between source memory and hippocampal function, it remains unknown whether changes in the brain precede improvements in memory or vice versa. To address this gap, the current study used an accelerated longitudinal design (n = 200, 100 males) to follow 4- and 6-year-old human children for 3 years. We traced developmental changes in source memory and intrinsic hippocampal functional connectivity and assessed differences between the 4- and 6-year-old cohorts in the predictive relations between source memory changes and intrinsic hippocampal functional connectivity in the absence of a demanding task. Consistent with previous studies, there were age-related increases in source memory and intrinsic functional connectivity between the hippocampus and cortical regions known to be involved during memory encoding. Novel findings showed that changes in memory ability early in life predicted later connectivity between the hippocampus and cortical regions and that intrinsic hippocampal functional connectivity predicted later changes in source memory. These findings suggest that behavioral experience and brain development are interactive, bidirectional processes, such that experience shapes future changes in the brain and the brain shapes future changes in behavior. Results also suggest that both timing and location matter, as the observed effects depended on both children's age and the specific brain ROIs. Together, these findings add critical insight into the interactive relations between cognitive processes and their underlying neurologic bases during development.SIGNIFICANCE STATEMENT Cross-sectional studies have shown that the ability to remember the contextual details of previous experiences (i.e., source memory) is related to hippocampal development in childhood. It is unknown whether hippocampal functional changes precede improvements in memory or vice versa. By using an accelerated longitudinal design, we found that early source memory changes predicted later intrinsic hippocampal functional connectivity and that this connectivity predicted later source memory changes. These findings suggest that behavioral experience and brain development are interactive, bidirectional processes, such that experience shapes future changes in the brain and the brain shapes future behavioral changes. Moreover, these interactions varied as a function of children's age and brain region, highlighting the importance of a developmental perspective when investigating brain-behavior interactions.

Neural Development of Memory and Metamemory in Childhood and Adolescence: Toward an Integrative Model of the Development of Episodic Recollection

Memory and metamemory processes are essential to retrieve detailed memories and appreciate the phenomenological experience of recollection. Developmental cognitive neuroscience has made strides in revealing the neural changes associated with improvements in memory and metamemory during childhood and adolescence. We argue that hippocampal changes, in concert with surrounding cortical regions, support developmental improvements in the precision, complexity, and flexibility of memory representations. In contrast, changes in frontoparietal regions promote efficient encoding and retrieval strategies. A smaller body of literature on the neural substrates of metamemory development suggests that error monitoring processes implemented in the anterior insula and dorsal anterior cingulate cortex trigger, and perhaps support the development of, metacognitive evaluationsin the prefrontal cortex, while developmental changes in the parietal cortex support changes in the phenomenological experience of episodic retrieval. Our conclusions highlight the necessity of integrating these lines of research into a comprehensive model on the neurocognitive development of episodic recollection.

Age- and performance-related differences in source memory retrieval during early childhood: Insights from event-related potentials

Across early childhood, children's ability to remember individual items and the details that accompany these items (i.e., episodic memory) improves greatly. Given that these behavioral improvements coincide with increases in age, effects of age and performance are often confounded. This study used event-related potentials (ERPs) to investigate age- and performance-related differences in the neural processes underlying the development of memory for details during early childhood. Using a source memory paradigm, ERP components related to episodic memory, the negative component (Nc), and late slow wave (LSW) were examined in 4- to 8-year-old children. Analyses focused on trials for which children correctly remembered the source related to an item versus trials where the item was remembered but the source was forgotten. Results revealed LSW, but not Nc, differed as a function of age and performance. Specifically, LSW effects were similar across source correct and source incorrect trials in all high-performing children and in low-performing older children; however, LSW effects differed across conditions in low-performing younger children. Results show developmental differences in retrieval processes across early childhood and highlight the importance of considering age and performance when examining electrophysiological correlates of episodic memory during development.

Differential Functional Connectivity in Anterior and Posterior Hippocampus Supporting the Development of Memory Formation

Neuroimaging evidence suggests that the development of the hippocampus, a brain structure critical for memory function, contributes to the improvements of episodic memory between middle childhood to adulthood. However, investigations on age differences in hippocampal activation and functional connectivity and their contributions to the development of memory have yielded mixed results. Given the known structural and functional heterogeneity along the long axis of the hippocampus, we investigated age differences in the activation and functional connectivity in hippocampal subregions with a cross-sectional sample of 96 participants ages 8–25 years. We found that anterior and posterior hippocampus supported memory formation, and there was overall stability in memory-related hippocampal activation with age. Without taking account of memory outcome, direct contrast between subregions showed higher functional connectivity of anterior, compared to the posterior hippocampus, with regions in the inferior frontal and lateral temporal lobes, and higher functional connectivity of posterior, compared to the anterior hippocampus, with regions in the medial and superior frontal, inferior parietal, and occipital lobes. A direct contrast between the memory-related connectivity patterns of anterior and posterior hippocampus identified a region in the medial frontal cortex, with which anterior and posterior hippocampus was differentially functionally connected. Finally, we identified age differences in memory-related differential hippocampal functional connectivity with several frontal and visual/sensory cortices, underscoring the importance of examining age differences in the patterns of hippocampal connectivity. Moreover, the specific patterns of differential anterior and posterior functional connectivity indicate an increase in the functional specialization along the long axis of the hippocampus and a dynamic shift in hippocampal connectivity patterns that supports memory development.

Neural substrates of mnemonic discrimination: A whole-brain fMRI investigation

INTRODUCTION

A fundamental component of episodic memory is the ability to differentiate new and highly similar events from previously encountered events. Numerous functional magnetic resonance imaging (fMRI) studies have identified hippocampal involvement in this type of mnemonic discrimination (MD), but few studies have assessed MD-related activity in regions beyond the hippocampus. Therefore, the current fMRI study examined whole-brain activity in healthy young adults during successful discrimination of the test phase of the Mnemonic Similarity Task.

METHOD

In the study phase, participants made "indoor"/"outdoor" judgments to a series of objects. In the test phase, they made "old"/"new" judgments to a series of probe objects that were either repetitions from the memory set (targets), similar to objects in the memory set (lures), or novel. We assessed hippocampal and whole-brain activity consistent with MD using a step function to identify where activity to targets differed from activity to lures with varying degrees of similarity to targets (high, low), responding to them as if they were novel.

RESULTS

Results revealed that the hippocampus and occipital cortex exhibited differential activity to repeated stimuli relative to even highly similar stimuli, but only hippocampal activity predicted discrimination performance.

CONCLUSIONS

These findings are consistent with the notion that successful MD is supported by the hippocampus, with auxiliary processes supported by cortex (e.g., perceptual discrimination).

Memory: Normative development of memory systems

During the past decades, abundant behavioral, clinical, and neuroimaging data have shown several memory systems in the brain. A memory system is a type of memory that processes a particular type of information, using specific mechanisms, with distinct neural correlates. What we call memory is therefore not a unitary capacity but a collection of distinct systems. From a developmental perspective, each memory system has its own developmental course. This explains the heterogeneity of children's mnemonic competencies: for example, 3-year-olds learn many new words and concepts every day but have trouble recalling in detail an event that happened the week before. In this chapter, we sum up major findings regarding the development from infancy to early adulthood of the main memory systems. Specifically, we report recent data regarding the development of declarative memory (i.e., episodic and semantic memory), and the relationship between the maturation of their neural correlates and the phenomena of infantile and childhood amnesia. We conclude by indicating some of the possible avenues for future research.

Volumetric and microstructural regional changes of the hippocampus underlying development of recall performance after extended retention intervals

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Unique developmental effects on recall over days rather than minutes.

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Development of visual recall explainable by visuo-constructive ability.

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Development of verbal recall not explained by verbal ability.

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Modest relationships between recall performance and hippocampus structure.

Performance on recall tests improves through childhood and adolescence, in part due to structural maturation of the medial temporal cortex. Although partly different processes support successful recall over shorter vs. longer intervals, recall is usually tested after less than an hour. The aim of the present study was to test whether there are unique developmental changes in recall performance using extended retention intervals, and whether these are related to structural maturation of sub-regions of the hippocampus. 650 children and adolescents from 4.1 to 24.8 years were assessed in total 962 times (mean interval ≈ 1.8 years). The California Verbal Learning Test (CVLT) and the Rey Complex Figure Test (CFT) were used. Recall was tested 30 min and ≈ 10 days after encoding. We found unique developmental effects on recall in the extended retention interval condition independently of 30 min recall performance. For CVLT, major improvements happened between 10 and 15 years. For CFT, improvement was linear and was accounted for by visuo-constructive abilities. The relationships did not show anterior-posterior hippocampal axis differences. In conclusion, performance on recall tests using extended retention intervals shows unique development, likely due to changes in encoding depth or efficacy, or improvements of long-term consolidation processes.

Building up and wearing down episodic memory: Mnemonic discrimination and relational binding

Our capacity to form and retrieve episodic memories improves over childhood but declines in old age. Understanding these changes requires decomposing episodic memory into its components. Two such components are (a) mnemonic discrimination of similar people, objects, and contexts, and (b) relational binding of these elements. We designed novel memory tasks to assess these component processes using animations that are appropriate across the life span (ages 4-80 in our sample). In Experiment 1, we assessed mnemonic discrimination of objects as well as relational binding, in a common task format. Both components follow an inverted U-shaped curve across age but were positively correlated only in the aging group. In Experiment 2, we examined mnemonic discrimination of context and its effect on relational binding. Relational memory in low-similarity contexts showed robust gains between the ages of 4 and 6, whereas 6-year-olds performed similarly to adults. In contrast, relational memory in high-similarity contexts showed more protracted development, with 4- and 6-year-olds both performing worse than young adults and not differing from each other. Relational memory in both context conditions declined in aging. This multiprocess approach provides important theoretical insights into life span changes in episodic memory. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Neural specificity of scene representations is related to memory performance in childhood

Successful memory encoding is supported by medial temporal, retrosplenial, and occipital regions, which show developmental differences in recruitment from childhood to adulthood. However, little is known about the extent to which neural specificity in these brain regions, or the distinctiveness with which sensory information is represented, continues to develop during middle childhood and how it contributes to memory performance. The present study used multivariate pattern analysis to examine the distinctiveness of different scene representations in 169 children and 31 adults, and its relation to memory performance. Most children provided data over up to three measurement occasions between 8 and 15 years (267 total scans), allowing us to examine changes in memory and neural specificity over time. Memory performance was lower in children than in adults, and increased in children over time. Different scenes presented during memory encoding could be reliably decoded from parahippocampal, lateral occipital, and retrosplenial regions in children and adults. Neural specificity in children was similar to adults, and did not change reliably over time. Among children, higher neural specificity in scene-processing regions was associated with better memory concurrently. These results suggest that the distinctiveness with which incoming information is represented is important for memory performance in childhood, but other processes operating on these representations support developmental improvements in memory performance over time.

Longitudinal trajectories of hippocampal and prefrontal contributions to episodic retrieval: Effects of age and puberty

The current study investigated longitudinal change in hippocampal and prefrontal contribution to episodic retrieval. Functional neuroimaging data were collected during an item-context association memory task for children between the ages of 8 and 14 with individuals scanned 1-3 times over the course of 0.75-3.7 years (Timepoint 1 N = 90; Timepoint 2 N = 83, Timepoint 3 N = 75). We investigated developmental changes in functional activation associated with episodic retrieval (correct item-context > incorrect item-context contrast) and asked whether pubertal changes contributed to developmental changes in pattern of activation. Non-linear developmental trajectories were observed. In the hippocampus, activation decreased with age during childhood and then increased into early adolescence. In the dorsolateral prefrontal cortex, activation was largely absent initially, but quickly accelerated over time. Independent of age, changes in pubertal status additionally predicted increases in item-context activation in initially older children, and decreases in initially younger children across both regions and two indicators of puberty: the Pubertal Development Scale and salivary testosterone. These findings suggest that changes in both age and pubertal status uniquely contribute to memory-related activation, and the timing of pubertal onset may play an important role in the neural mechanisms supporting memory retrieval.

The influence of age and performance on hippocampal function and the encoding of contextual information in early childhood

Studies in school-aged children and adults consistently implicate hippocampus, cortical regions, and their interaction as being critical for memory. However, few studies have examined this neural network in younger children (<8 years), despite the fact that behavioral studies consistently report substantial improvements in memory earlier in life. This study aimed to fill this gap by integrating task-based (i.e., memory encoding task) and task-free fMRI scans in 4- to 8-year-old children. Results showed that during memory encoding the hippocampus and several cortical regions (e.g., inferior frontal gyrus, IFG) were activated, consistent with findings in older individuals. Novel findings during memory encoding showed: 1) additional regions (i.e., orbital frontal gyrus, OFG) were recruited, 2) hippocampal activation varied due to age and performance, and 3) differentiation of connectivity between hippocampal subregions and IFG was greater in older versus younger participants, implying increased speicalization with age. Novel findings from task-free fMRI data suggested the extent of functional differentiation along the longitudinal axis of the hippocampus, particularly between hippocampus and OFG, was moderated by both age and performance. Our findings support and extend previous research, suggesting that maturation of hippocampal activity, connectivity, and differentiation may all contribute to development of memory during early childhood.

Imaging episodic memory during development and childhood epilepsy

Epilepsy affects 2.2 million adults in the USA, with 1 in 26 people developing epilepsy at some point in their lives. Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy as medial structures, and the hippocampus in particular, are prone to generating seizures. Selective anterior temporal resection (which removes the hippocampus) is the most effective intractable TLE treatment, but given the critical role of the mesial temporal lobe in memory functioning, resection can have negative effects on this crucial cognitive skill. To minimize the adverse impact of temporal lobe surgery on memory functioning, reliable pre-surgical guides are needed. Clinical functional magnetic resonance imaging (fMRI) provides reliable, noninvasive guidance of language functioning and plays a growing role in the pre-surgical evaluation for epilepsy patients; however, localization of memory function in children with epilepsy using fMRI has not been established. Aside from the lack of neuroimaging memory studies in children with TLE, studies of typical development are limited. This review will focus on the functional anatomy of memory systems throughout development, with a focus on TLE. TLE provides the ideal model from which to understand memory function and the limits of plasticity and compensation/reorganization throughout development.

Development and Decline of the Hippocampal Long-Axis Specialization and Differentiation During Encoding and Retrieval of Episodic Memories

Change in hippocampal function is a major factor in life span development and decline of episodic memory. Evidence indicates a long-axis specialization where anterior hippocampus is more engaged during encoding than during retrieval, and posterior more engaged during retrieval than during encoding. We tested the life span trajectory of hippocampal long-axis episodic memory-related activity and functional connectivity (FC) in 496 participants (6.8–80.8 years) encoding and retrieving associative memories. We found evidence for a long-axis encoding–retrieval specialization that declined linearly during development and aging, eventually vanishing in the older adults. This was mainly driven by age effects on retrieval, which was associated with gradually lower activity from childhood to adulthood, followed by positive age relationships until 70 years. This pattern of age effects characterized task engagement regardless of memory success or failure. Especially for retrieval, children engaged posterior hippocampus more than anterior, while anterior was relatively more activated already in teenagers. Significant intrahippocampal connectivity was found during task, which declined with age. The results suggest that hippocampal long-axis differentiation and communication during episodic memory tasks develop rapidly during childhood, are different in older compared with younger adults, and that the age effects are related to task engagement, not the successful retrieval of episodic memories specifically.

Memory-related hippocampal activation in the sleeping toddler

Nonhuman research has implicated developmental processes within the hippocampus in the emergence and early development of episodic memory, but methodological challenges have hindered assessments of this possibility in humans. Here, we delivered a previously learned song and a novel song to 2-year-old toddlers during natural nocturnal sleep and, using functional magnetic resonance imaging, found that hippocampal activation was stronger for the learned song compared with the novel song. This was true regardless of whether the song was presented intact or backwards. Toddlers who remembered where and in the presence of which toy character they heard the song exhibited stronger hippocampal activation for the song. The results establish that hippocampal activation in toddlers reflects past experiences, persists despite some alteration of the stimulus, and is associated with behavior. This research sheds light on early hippocampal and memory functioning and offers an approach to interrogate the neural substrates of early memory.

Long-term effects of prenatal drug exposure on the neural correlates of memory at encoding and retrieval

The objective of the current study was to examine what stage of memory (encoding or retrieval) may be compromised in adolescents with a history of prenatal drug exposure (PDE) and how the effects of PDE on memory ability are substantiated at the neural level. To achieve this goal, we examined memory performance and associated brain activations in adolescents with and without a history of PDE via event-related fMRI during encoding and retrieval. Consistent with previous studies, we found that PDE subjects remembered fewer items than community comparison subjects. However, there were no differences in behavior after adjusting for correct rejections (i.e., d'). Novel extensions of previous work are findings that PDE is associated with changes in brain activation during memory encoding but not during retrieval. These results suggest that less optimal memory performance often observed in adolescents with a history of PDE may result from variations in encoding rather than retrieval processes.

Age- and performance-related differences in encoding during early childhood: insights from event-related potentials

Previous studies have found that children show rapid and significant improvements in their ability to remember individual items and the contextual details that surround these items (i.e., episodic memory) during early childhood. Encoding processes have been suggested to contribute to the development of episodic memory; however, few studies have investigated encoding processes. The goal of the current study was to examine age- and performance-related effects on encoding in children between 4 and 8 years of age using event-related potentials (ERPs). Results revealed effects of both age and performance on encoding, as indexed by the ERPs response. However, the nature of these effects differed between subsequent recognition and subsequent recollection, as well as for the two ERP components (i.e., Nc and LSW) examined. These findings are important as they contribute empirical evidence that encoding processes show developmental change across early childhood. In addition, these findings highlight the importance of controlling for performance differences in future studies examining developmental changes in episodic memory.

Frontoparietal Structural Connectivity in Childhood Predicts Development of Functional Connectivity and Reasoning Ability: A Large-Scale Longitudinal Investigation

Prior research points to a positive concurrent relationship between reasoning ability and both frontoparietal structural connectivity (SC) as measured by diffusion tensor imaging (Tamnes et al., 2010) and frontoparietal functional connectivity (FC) as measured by fMRI (Cocchi et al., 2014). Further, recent research demonstrates a link between reasoning ability and FC of two brain regions in particular: rostrolateral prefrontal cortex (RLPFC) and the inferior parietal lobe (IPL) (Wendelken et al., 2016). Here, we sought to investigate the concurrent and dynamic, lead-lag relationships among frontoparietal SC, FC, and reasoning ability in humans. To this end, we combined three longitudinal developmental datasets with behavioral and neuroimaging data from 523 male and female participants between 6 and 22 years of age. Cross-sectionally, reasoning ability was most strongly related to FC between RLPFC and IPL in adolescents and adults, but to frontoparietal SC in children. Longitudinal analysis revealed that RLPFC-IPL SC, but not FC, was a positive predictor of future changes in reasoning ability. Moreover, we found that RLPFC-IPL SC at one time point positively predicted future changes in RLPFC-IPL FC, whereas, in contrast, FC did not predict future changes in SC. Our results demonstrate the importance of strong white matter connectivity between RLPFC and IPL during middle childhood for the subsequent development of both robust FC and good reasoning ability.SIGNIFICANCE STATEMENT The human capacity for reasoning develops substantially during childhood and has a profound impact on achievement in school and in cognitively challenging careers. Reasoning ability depends on communication between lateral prefrontal and parietal cortices. Therefore, to understand how this capacity develops, we examined the dynamic relationships over time among white matter tracts connecting frontoparietal cortices (i.e., structural connectivity, SC), coordinated frontoparietal activation (functional connectivity, FC), and reasoning ability in a large longitudinal sample of subjects 6-22 years of age. We found that greater frontoparietal SC in childhood predicts future increases in both FC and reasoning ability, demonstrating the importance of white matter development during childhood for subsequent brain and cognitive functioning.

Hippocampal maturity promotes memory distinctiveness in childhood and adolescence

Adaptive learning systems need to meet two complementary and partially conflicting goals: detecting regularities in the world versus remembering specific events. The hippocampus (HC) keeps a fine balance between computations that extract commonalities of incoming information (i.e., pattern completion) and computations that enable encoding of highly similar events into unique representations (i.e., pattern separation). Histological evidence from young rhesus monkeys suggests that HC development is characterized by the differential development of intrahippocampal subfields and associated networks. However, due to challenges in the in vivo investigation of such developmental organization, the ontogenetic timing of HC subfield maturation remains controversial. Delineating its course is important, as it directly influences the fine balance between pattern separation and pattern completion operations and, thus, developmental changes in learning and memory. Here, we relate in vivo, high-resolution structural magnetic resonance imaging data of HC subfields to behavioral memory performance in children aged 6-14 y and in young adults. We identify a multivariate profile of age-related differences in intrahippocampal structures and show that HC maturity as captured by this pattern is associated with age differences in the differential encoding of unique memory representations.