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Exploring Hippocampal Structural Differences in Habitual vs Non-habitual Nappers During Early Childhood
Get PDFDuring sleep, memories become less vulnerable to interference, both during overnight sleep and naps. Previous research in adults suggests this effect is partially due to a “transfer” of memories from hippocampus to cortex, but there is little research investigating this process in children. Existing literature suggests habitually napping children need naps more than non-habitually napping children because their hippocampus is less mature. This study examines the relation between habitual versus non-habitual nappers and the hippocampus in early childhood. The participants are part of a larger ongoing study, from which we had 21 participants (Mage= 4.49 years, SD=0.51, 9 female). Of the 21 participants, 8 were nappers (napped 5+ days/week) and 13 were non-nappers (napped <5 days/week). Hippocampal volumes were extracted from T1 weighted MRI scans via FreeSurfer 6.0.0 and refined with a Segmentation Adapter Tool (Morey et al., 2009). Subregions of hippocampal head, body, and tail were identified via standard anatomical landmarks (Watson et al., 1992; Weiss et al., 2005). Preliminary analyses examined possible confounding differences between groups (age, sex, and intercranial volume). There were no differences, thus these measures were not controlled for. Results showed significant differences in hippocampal tail volumes. In the left hemisphere, nappers had larger volumes than non-nappers. Although these are preliminary results, the findings support that variation in hippocampal development may relate to nap status in developing children. Future research will focus on increased sample sizes and investigate other brain regions to determine the specificity of these effects.National Institute of Health (NIH),
National Science Foundation (NSF
Relations between amygdala:hippocampus ratios and depressive symptoms in typically developing 4- to 8-year-old children
Get PDFPrevious literature suggests that the coordination between the amygdala and hippocampus, regions critical for encoding of complex memory and emotion, are associated with depression and risk factors for depression, such as negative memory bias, during adulthood (Yavas et al., 2019; Gerritsen et al., 2012). Research on adolescents ages 8-17 suggests that increased amygdala:hippocampus ratios are related to the severity of anxiety in pediatric major depression (MacMillan et al., 2003). Although associations between amygdala:hippocampus ratios and depression are well-documented in older samples, these associations are not well-explored in early childhood (i.e., <8 years). Given this is a developmental period during which both the amygdala and the hippocampus undergo structural and functional changes (Riggins et al., 2018; Stern et al., 2019), it may be especially important to understand how these developmental changes relate to depressive symptoms in early childhood. The present research aims to address this gap in the literature.
Specifically, we examined depressive symptoms and amygdala:hippocampus ratios in typically developing 4- to 8-year-old children drawn from a larger, longitudinal study on brain development in early childhood (N=200, 100 female; Riggins et al., 2018). Depression scores were assessed using the Children’s Depression Inventory (CDI; Kovacs, 1985). Brain region volumes were collected using a standard resolution (.9mm3), T1-weighted whole brain structural magnetic resonance imaging (MRI) scan and processed using FreeSurfer (v5.1). In addition to amygdala and hippocampal volumes, intracranial volume (ICV) was collected as a control for participant head size. Analysis using partial correlations revealed a significant association between total amygdala:hippocampus ratios and depressive symptoms, r(50) = -.234, p = .048. The association between right amygdala:hippocampus ratios and depressive symptoms approached significance, r(50) = -.218, p = .060, and the association between left amygdala:hippocampus ratios and depressive symptoms were not significant. Contrary to previous research, smaller amygdala:hippocampus ratios predicted increased depressive symptoms. Implications for this research are discussed further
Relations between Memory Measures and Hippocampal Volumes in Early Childhood
Get PDFThe phenomenon of childhood amnesia, in which only a mere fraction of childhood experiences is remembered, may be due to changes in underlying neural mechanisms supporting memory (Willoughby et al., 2012; Bauer, 2007). However, it is unknown whether lab tasks used to measure childhood memory skills map onto everyday life experiences. This study aims to address that gap through an investigation of two different measures completed by 200 4- to 8-year-old children. One task is a rich open-ended autobiographical interview examining recall for real-world events; the other is a controlled laboratory-based assessment examining memory for temporal order using a series of child-appropriate pictures. This study asks whether both tasks show relations to 1) age group, 2) underlying neural mechanisms, and 3) performance as compared to each other. The hippocampus is a likely candidate underlying behavioral changes during early childhood because it undergoes significant development during this time (Gogtay et al., 2006; Lavenex & Lavenex, 2013) and supports memory in school-aged children and adults (Ghetti & Bunge, 2012). Autobiographical memories were scored using a modified interview coding scheme based on Levine et al. (2002). Temporal order was scored as proportion of adjacent pictures correctly ordered across two 9-item sequences. Hippocampal subregions were delineated using manually identified anatomical landmarks (Riggins et al., 2018). Preliminary results indicate age-related performance differences and hippocampal volume correlations. This work contributes to knowledge about the extent to which naturalistic versus lab-based tasks similarly measure memory abilities.National Institutes of Health HD0795
Exploring neural correlates of depression in childhood: The relation between amygdala:hippocampus ratios and CDI depression scores in 4-8 year olds
Get PDFNationally representative studies have shown that mood disorders such as depression and anxiety are widely prevalent in children, with depression acting as one of the leading causes of disability in the United States (Ghandour et al., 2018; Schmaal et al., 2016). Research on adults suggests that depression and mood regulation can be linked to brain structure and function, specifically abnormalities with the amygdala and hippocampus (Yavas et al., 2019; Gerritsen et al., 2012). Interestingly, these brain regions have been shown to undergo structural and functional changes in early childhood that correspond with critical developmental changes in behavior (e.g., Riggins et al., 2018; Stern et al., 2019). Despite these changes, there is very little research investigating the relation between the brain and depressive symptoms in children, particularly during early childhood. Furthering the understanding of the relation between structural changes in brain and depressive symptoms is critically important not only for addressing high rates of childhood depression, but also for understanding the etiology and course of depression from early childhood into adulthood. This information could inform future intervention strategies and improve our understanding of normative and non-normative development in early childhood. This study aims to fill this gap by assessing the association between amygdala and hippocampus volumes and depressive symptoms cross sectionally and longitudinally in children ages 4-8 years
HIPPOCAMPAL VOLUME, CAREGIVER CHANGES, AND FAMILY COHESION IN ADOLESCENTS WITH PRENATAL DRUG EXPOSURE
No full textPrenatal exposure to drugs has been associated with changes in neurocognitive development, such as delays in language development and sensorimotor development. However, the effects of prenatal drug exposure (PDE) can also be modified by the postnatal environment. The present study explored associations between PDE and postnatal family functioning on adolescent brain development.
Parent-infant dyads were enrolled at delivery from an urban University Hospital. Eligibility included positive (cocaine/heroin) maternal/infant urine toxicology or maternal self-report of cocaine/heroin use during pregnancy. A Community Comparison (CC) sample, of the same age and key demographic, was enrolled at age 6 years. Caregiver changes were documented every six months throughout the first 7 years of the study.
Adolescents (N = 50) completed structural MRI scans. Volumetric segmentation of the hippocampus was performed using FreeSurfer v5.2. Hippocampal volume was adjusted for intracranial volume, age, and sex. At this time, caregivers and adolescents also reported on family functioning by completing the Self-Report Family Instrument. The subscales of interest were family cohesion and health competence.
Participants with PDE had more caregiver changes, reported less family cohesion, less health competence, and had larger hippocampal volumes compared to the CC group. Additionally, within the PDE group, caregiver changes were correlated with right hippocampal volume; however the bilateral hippocampal volumes of those with any history of caregiver changes vs none were not significantly different. Overall, findings demonstrate lasting impacts of PDE but suggest that postnatal caregiving environments may also contribute to neurodevelopment
Relations Between Hippocampal Volume and Story Recall in Early Childhood
Get PDFResearch in adults and children suggest the hippocampus plays an important role in verbal memory (Ezzati et al., 2015; Gold & Trauner, 2014). However, links between verbal memory and the hippocampus in younger children remain relatively under investigated. This relation is important to study during early childhood (i.e., before 6 years) for at least two reasons. First, memory changes rapidly during this time and second, research in children suggests that age- related differences exist between memory and hippocampal subregion volumes (e.g. Riggins et al., 2015; Allard, Canada, & Riggins, March 2019). The current study addresses a gap in the literature by investigating the potential relation between hippocampal subregion volumes and verbal memory in early childhood.
A total of 200 children, aged 4-8 years old (mean age=6.21 years, SD=0.11), were enrolled in a larger study on hippocampal memory development. Of these, 177 provided usable
behavioral and MRI data. To assess verbal memory performance in these children, the stories subtest of the Children's Memory Scale was administered (Cohen, 1997). In the task, participants heard two stories read aloud by a researcher and were then asked to recall those stories immediately after hearing them, again one hour later, and again one week later. For the current study, analyses focused on the hour-delay performance in order to assess long term memory without the additional prompting that happened before the week-delay performance. Performance on the task was determined by the number of remembered verbatim story units. The maximum number of stories units to be remembered was 57 for both stories heard. Approximately one week following the verbal memory task, a T1-weighted structural MRI scan (0.9 mm3) was obtained. Hippocampal volumes were estimated via Freesurfer v5.1 (Fischl, 2012) and refined using ASAT (Wang et al., 2011). Hippocampal volumes were then divided into subregions (head, body, tail) using standard anatomical landmarks (Weiss, Dewitt, Goff, Ditman, & Heckers, 2005; Watson et al., 1992).
Initial analyses examining hippocampal volume and verbal memory performance was non- significant. However, when a median age split was conducted, preliminary findings assessing relations between recall and hippocampal volumes revealed that younger (4- 6.13 years), but not older children (6.14-9 years) showed a significant positive relation between number of story units recalled and volume of the left hippocampal body (r=0.244, n=79, p=0.028).
These findings are consistent with previous research that suggests developmental differences exist in brain-behavior relations during early childhood. It also supports the notion that a mature hippocampus is not necessarily larger in size (Riggins et al., 2015). These results reinforce an emerging body of work that propose age-related differences in associations between memory and hippocampal subregion volumes during development. Specifically, these results are consistent with previous findings that showed age-related differences between hippocampal body and performance on a visual spatial memory task and source memory in younger but not older children (Allard, Canada, & Riggins, March 2019; Riggins et al., 2015).Neurocognitive Development Lab and NIH Grant RO1 5205310 (TR)
Exploring Differences in Hippocampal Structure between Habitual vs Non-habitual Nappers during Early Childhood
No full textWhen we sleep, our memories are consolidated and become less vulnerable to interference, both during overnight sleep and during naps. Previous research in adults suggests this effect is at least partially due to a “transfer” of these memories from the hippocampus to the cortex. Although a similar process likely takes place in young children, there is little research investigating it. The existing literature suggests habitually napping children may need naps more than non-habitually napping children because their brain is less mature. This study aims to examine relations between habitual versus non-habitual nappers and brain development in early childhood. The focus was on the hippocampus, a structure that is critical for memory and shows protected development during early childhood. At the time of this report, 21 children provided useable data (Mage = 4.49 years, SD = 0.51, 9 female). Of these participants, 8 were habitual nappers and 13 were non-habitual nappers. Hippocampal volumes were extracted using a combination of manual and automated methods. Results revealed in the left hippocampal tail, habitual nappers had larger volumes compared to non-habitual nappers. Although these are preliminary results and do not survive correction for multiple comparisons, the findings support that variation in hippocampal development may relate to nap status in developing children. Future research will examine a larger sample size and investigate other brain regions to determine the specificity of these effects.NIH (National Institute of Health)
NSF (National Science Foundation
Exploring Relations Between Memory and Internalizing and Externalizing Behaviors in Childhood
Get PDFThere is a growing field of research which suggests internalizing and externalizing disorders cause disruptions in cognitive functioning, including memory. This association has primarily been explored in adults. This honors thesis explores the potential connection between mnemonic discrimination as a measure of episodic memory and internalizing and externalizing behaviors in young children. Researchers collected data on memory using a Mnemonic Similarity Task (MST) in children between 3 and 5 years of age and related their performance to ratings of their internalizing and externalizing behavior from the Child Behavior Checklist (CBCL) completed by a parent or guardian. Results did not support the hypothesis that internalizing and externalizing behaviors were related to poor episodic memory, as has been shown in adult populations. Future research with older children should be conducted in order to understand when during development that internalizing and externalizing behaviors begin to inhibit episodic memory.NICHD HD07951
Exploring Sleep-Dependent Memory Consolidation in Preschoolers
No full textSleep is important for memory. This may be especially true in early childhood, when sleep demands are high. In fact, previous research has shown that, when preschool children who typically nap are prevented from doing so, their learning and memory suffers. However, the specific benefits of sleep for memory and the neural mechanisms associated with these benefits are still unclear. For example, does sleep benefit memory generally or certain kinds of memory (e.g., memory for specific details vs memory for general items). Does sleep simply “protect” memories or can it ”enhance” them? To begin to address these questions, we are investigating how sleep impacts memory in early childhood. We will investigate the impact of an afternoon nap and subsequent overnight sleep on memory performance. The study will (eventually) enroll 180 preschool-aged children (3.0-5 years) who are habitual nappers (children who nap at least five times a week). Each child will complete the Mnemonic Similarity Task (MST) to evaluate precision and generalized memory across a wake condition, nap condition and overnight sleep condition. The MST is a variant of a traditional recognition memory task that includes perceptually similar examples of studied items as lures. This task will allow us to explore the types of memories that are impacted by sleep and the type of impact made. For data analysis, the Lure Discrimination Index (LDI) will be calculated from the MST data in order to measure precision memory performance. We will compare LDI to standard metrics of memory, such as corrected recognition scores, which measure general memory. From this investigation we hope to further understand the impact of sleep on memory in young children. To date, 7 participants have provided data, and data collection is still ongoing with an estimated sample size of 20 by the time of this presentation
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