Psychology

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MULTIMODAL ANALYSIS OF NEURAL SIGNALS RELATED TO SOURCE MEMORY ENCODING IN YOUNG CHILDREN
(2024) Lei, Yuqing; Riggins, Tracy; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The emergence of source memory is an important milestone during memory development. Decades of research has explored neural correlates of source memory using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). However, connections between findings from the two approaches, particularly within children, remain unclear. This dissertation identified fMRI-informed cortical sources of two EEG signals during memory encoding, the P2 and the late slow wave (LSW), that predicted subsequent source memory performance in a sample of children aged 4 to 8 years. Both P2 and LSW were source localized to cortical areas of the medial temporal lobe (MTL), reflecting MTL’s crucial role in both early-stage information processing and late-stage integration of memory, which also validated LSW’s suspected role in memory updating. The P2 effect was localized to all six tested subregions of cortical MTL in both left and right hemispheres, whereas the LSW effect was only present in the parahippocampal cortex and entorhinal cortex. P2 was additionally localized to multiple areas in the frontoparietal network, a cortical network known as the “attention network”, highlighting interactions between memory encoding and other cognitive functions. These results reflect the importance of considering both spatial and temporal aspects of neural activity to decode memory mechanism, and demonstrated the potential of combining multimodal measures in children, paving the way for future developmental research.
ROLE OF PROJECTIONS FROM ORBITOFRONTAL CORTEX TO DORSAL STRIATUM IN INCUBATION OF OXYCDONE CRAVING
(2023) Lin, Hongyu; Li, Xuan; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Oxycodone seeking progressively increases during abstinence and maintains for an extended period, a phenomenon termed incubation of oxycodone craving. We previously found that the orbitofrontal cortex (OFC) plays a causal role in this incubation. Here, we aimed to identify critical downstream regions of OFC in incubation of oxycodone craving by focusing on the central to medial portion of the dorsal striatum (DS), based on previous anatomical evidence. We first measured projection-specific activation on abstinence day 15 seeking test by using cholera toxin b (retrograde tracer, injected into DS) +Fos (activity marker) double-labeling in the OFC. Next, we determined the effect of pharmacological reversible inactivation of DS on incubated oxycodone seeking on abstinence day 15. We then used an anatomical asymmetrical disconnection procedure to determine whether OFC to DS projections contribute to incubated oxycodone seeking.
Relations Between Latent Episodic Memory, Nap Habituality, and the Cortex During Childhood
(2023) Allard, Tamara Lynn; Riggins, Tracy; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
During childhood, episodic memory demonstrates marked improvements that are supported by the protracted development of the hippocampus and a larger network of cortical regions. To date, most research has focused on associations with the hippocampus in this age group. Few studies have explored the contribution of cortical regions and no studies have explored this longitudinally. Thus, the first aim of this dissertation was to examine the longitudinal co-development of cortical thickness and surface area in memory-related cortical regions with a latent episodic memory variable in 4- to 8-year-old children (N = 177). Findings, uncorrected for multiple comparisons, demonstrated that a thinner cortex in multiple episodic memory network regions (i.e., inferior frontal gyrus, inferior parietal sulcus, lingual gyrus, middle temporal gyrus, precuneus, lateral occipital cortex, superior frontal gyrus, superior parietal lobule, superior temporal gyrus, and temporal pole) at age 4 predicted more rapid improvements in memory performance from age 4 to 6 years. Similarly, greater surface area in the precuneus and less surface area in the medial orbitofrontal gyrus at age 4 also predicted more rapid improvements in memory performance from age 4 to 6 years. Additionally, results revealed that several regions demonstrate parallel co-development with latent episodic memory performance from age 4 to 8 years. Specifically, greater changes in cortical thickness and surface area of the entorhinal cortex were associated with greater changes in memory from age 4 to 6 years. Furthermore, cortical thickness of entorhinal cortex and surface area of anterior cingulate cortex, entorhinal cortex, inferior parietal sulcus, lingual gyrus, and superior temporal gyrus showed co-development with latent episodic memory from age 6 to 8 years. Together, these findings suggest that cortical thickness and surface area of the episodic memory network support improvements in memory performance during childhood. However, these findings did not survive correction for multiple comparisons. Although age-related differences were one focus of this investigation, individual differences were another. Specifically, during childhood children transition away from afternoon napping. This transition has previously been associated with differences in memory consolidation abilities and hippocampal maturation. These associations suggest that habitual nappers require more regular sleep to consolidate memories due to an immature episodic memory network. However, limited work has examined these associations outside the hippocampus. Therefore, the second aim of this dissertation was to examine whether regions that support longitudinal memory development differ as a function of nap habituality (N = 44). Findings revealed significant differences in cortical thickness of right inferior frontal gyrus and surface area of lateral occipital cortex, such that non-nappers demonstrated a thinner cortex and greater surface area in these regions compared to nappers, though these findings did not survive correction for multiple comparisons. Thus, although there is some evidence that memory-related cortical regions may differ based on nap habituality, additional work is needed to support this claim. Together this dissertation provides new data on the co-development of memory with brain structure in the episodic memory network and identifies individual differences that may be associated with these brain structures.
Perceptual Decision Impairments in Obsessive-Compulsive Disorder: State and Trait Symptom Effects and The Role of Working Memory
(2020) Kaplan, Claire; Solway, Alec; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Computational models of decision making have identified a relationship between obsessive-compulsive symptomatology and impairments in perceptual evidence accumulation. Past studies have suggested that these impairments in perceptual processing give rise to clusters of OCD symptoms (for example, not effectively “perceiving” that a door is locked or that one’s hands are clean gives rise to compulsive checking or washing). That interpretation has implications for our understanding of the disorder and warrants further testing; one way to investigate that is to determine whether such impairments correlate better with state-level symptoms (i.e., obsessions and compulsions during task performance) or trait-level symptoms (i.e., in general/past week). Using hierarchical drift-diffusion modeling, the current study examines this question in consideration of the alternate possibility that these decision impairments are simply a reflection of off-task processing of active obsessions and compulsions. We also examine whether working memory may mitigate such impairments, in light of prior studies that have associated larger working memory spans with better suppression of distractors and with faster perceptual evidence accumulation. 161 adults completed the random dot-motion task, OSPAN working memory task, and OCD symptom questionnaires online. Participants who reported greater obsessive-compulsive symptoms demonstrated slower evidence accumulation (“drift rate”) in the dot-motion task. These drift rate reductions were better explained by state-level symptom severity than trait-level severity. Working memory span showed a significant negative interaction with state-level symptom score on drift rate, however only for the easiest trials. While the current study does not negate a role of perceptual evidence accumulation deficits in the pathogenesis of OCD, these findings support the possibility that such deficits may also be brought about by active symptoms during task execution. We discuss using impairments in drift rate to approximate attentional bias for off-task symptoms, as this provides a novel computational framework in closer alignment with existing clinical models of OCD.
Understanding the Relevance of Extended Amygdala Reactivity to Dispositional Negativity
(2021) Grogans, Shannon Elizabeth; Shackman, Alexander J; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Elevated dispositional negativity (DN; i.e., neuroticism/negative emotionality) is associated with a range of deleterious outcomes, including mental illness. Yet, DN’s neurobiology remains incompletely understood. Prior work suggests that DN reflects heightened threat-elicited reactivity in the extended amygdala (EAc), a circuit encompassing the central nucleus (Ce) and the bed nucleus of the stria terminalis (BST), and that this association may be intensified for uncertain threat. We utilized a multi-trait, multi-occasion DN composite and neuroimaging assays of threat anticipation and perception to demonstrate that individuals with elevated DN show heightened BST activation during threat anticipation. Analyses revealed that DN is uniquely predicted by BST reactivity to uncertain threat. DN was unrelated to Ce activation during threat anticipation or EAc activation during ‘threatening’-face presentation. Follow-up analyses revealed that the threat paradigms are not interchangeable probes of EAc function. These observations lay the foundation for future studies necessary to determine causation and improve interventions.
Assessing the Impact of Typical Variations in Stressful Life Events on Hippocampal Development in Childhood
(2021) Botdorf, Morgan; Riggins, Tracy; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The negative impact of extreme stress on early brain development is well-documented. An emerging body of work suggests that less extreme and more typical variations in stressful experiences (e.g., parental divorce, changing schools) may also exert an impact on the brain, especially in early childhood; however, more systematic research is needed. Across, three studies, this dissertation addressed this gap by exploring effects of typical variations in stressful life events on development of the hippocampus, a brain region highly susceptible to stress. Study 1a assessed the impact of stressful life events on the development of hippocampal subfield volumes (i.e., CA1, CA2-4/dentate gyrus (DG), subiculum) in an accelerated longitudinal sample of 102 4- or 6-year-old children who were each followed for 3 years. Analyses revealed that experiencing more stressful life events was related to smaller CA1 and CA2-4/DG volumes in the 6- (but not 4-) year-old cohort. Study 1b used the same sample described in Study 1a to investigate the impact of stressful life events on functional connectivity between the hippocampus and stress-related cortical regions. Analyses revealed a significant association in the 4- (but not 6-) year-old cohort, such that experiencing more stressful life events was related to greater connectivity between the hippocampus and the insula, a region important for emotional processing. Study 2 assessed moderating effects of sex and socioeconomic status (SES) on the association between stressful events and hippocampal subfield volumes using a large (n = 4,348), diverse subsample of 9-10-year-old adolescents from the Adolescent Brain and Cognitive Development Study. Analyses revealed that stressful life events were related to smaller subiculum volumes, but these associations did not vary by sex or SES. Overall, these findings provide evidence of the impact of typical variations in stressful life events on both hippocampal structure and functional connectivity. Findings also highlight the complexity of stress effects on the brain as these experiences may impact the hippocampus in an age-dependent manner. These results advance our current understanding of how stress influences hippocampal development and pave the way for studies to assess the implications of findings both for cognitive processes and the development of stress-related disorders.
Is nap status related to memory, sleep physiology, and the hippocampus in early childhood?
(2020) Allard, Tamara L; Riggins, Tracy; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Research suggests there may be links between developmental changes in sleep (e.g., transition out of a nap), memory, and brain (specifically, hippocampus). The purpose of this investigation was to explore differences in sleep physiology, visuospatial memory, and hippocampal volume based on nap status. Participants were 3 to 5-year-old children (n=51) who were habitual nappers (napping >5 days/week), semi-habitual nappers (3–4 days/week), or non-nappers (<2 days/week). Participants completed a memory task before and after a wake and nap session. Polysomnography (PSG) and hippocampal volumes were also assessed. Findings demonstrated that, regardless of nap status, children performed better on a memory task following a nap. PSG revealed that habitual nappers spent marginally more time in nREM2 sleep and less time in SWS compared to semi-habitual nappers. Finally, non-nappers demonstrated a larger hippocampus than the other groups. These findings support the suggestion that developmental differences in these domains are related during childhood.
Conflict and Competition between Model-based and Model-free Control
(2020) Lei, Yuqing; Solway, Alec; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
There are two learning systems behind human decision-making: the model-based (MB) system and the model-free (MF) system. While they both contribute to decision-making behaviors, it is not clear how the two systems interact to formulate a single decision, especially when they are in conflict. This present thesis defines decision conflict between the systems in two popular binary-choice tasks: Daw’s Two-step task and Kool’s Rocket Task. We used hierarchical modeling to identify conflict-related changes during decision process using the Drift-Diffusion Model (DDM). Evidence showed that the MB system compromises when there is a conflict with the MF system, whether the conflict is on the valuational level or action level. We also looked at how a key component of obsessive compulsive disorder (OCD), the cognitive self-consciousness (CSC), affects the two learning systems during decision.
THE IMPACT OF MILD TRAUMATIC BRAIN INJURY ON TIME-FREQUENCY ERP MEASURES AND NEUROPSYCHOLOGICAL FUNCTIONING: A LONGITUDINAL STUDY OF ACUTELY INJURED SERVICE MEMBERS
(2020) Watts, Adreanna Massey; Bernat, Edward; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Traumatic Brain Injury (TBI) is the most common injury in recent military conflicts, with nearly 500,000 service members sustaining a TBI since 2000. Mild TBI (mTBI), or concussion, is by far the most common type of TBI and has been associated with long-term cognitive complaints and functional impairment. While clinical assessment of mTBI (i.e., MRI and performance-based cognitive testing) occasionally captures subtle abnormalities in the acute period following mTBI, these measurements lack the sensitivity to assess the time course of cognitive recovery from mTBI. The current study assessed cognitive changes from the acute to chronic period following mTBI using advanced time-frequency event-related potential (ERP) analysis, which isolates rapid regional brain activity and measures the functional communication within and between brain networks in response to varying task stimuli. The validity of these ERP biomarkers was evaluated with correlations between abnormal ERP findings and widely used clinical measures of cognitive functioning (i.e., neuropsychological tests and self-reported cognitive symptoms). Differences between mTBI caused by blast explosion versus impact to the head were also evaluated. A sample of 173 service members, comprising an mTBI group, an orthopedically-injured control group, and a healthy control group, completed ERP, neuropsychological, and self-report assessments within weeks following injury and again six months later. Results suggested that mTBI leads to cognitive changes that persist in the acute to post-acute period following injury (i.e., up to 12 weeks). These cognitive changes were reflected by alterations in ERP time-frequency amplitude and functional connectivity measures, and they remained apparent even when controlling for psychiatric symptoms. ERP differences were also evident between blast-related and impact-related mTBI. Conversely, neuropsychological test performance was not sensitive to mTBI. Abnormal ERP time-frequency measures were related to self-reported cognitive symptoms, suggesting these ERP measures are valid biomarkers of cognitive difficulties following mTBI. Critically, cognitive functioning as assessed by ERP measures returned to a level indistinguishable from controls 7-9 months following mTBI, even though more than a third of mTBI patients continued to report cognitive symptoms. These persistent cognitive complaints were more related to post-injury psychiatric symptoms than to the direct effects of brain injury.
Examining the co-development of episodic memory and hippocampal subfields – A longitudinal study
(2020) Canada, Kelsey Leigh; Riggins, Tracy; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Episodic memory is a cornerstone ability that allows one to recall past events and the context in which they occur. Many different tasks have been used to assess the development of episodic memory during early childhood. Previous longitudinal work on individual tasks has noted accelerated changes from approximately 5 to 7 years, suggesting non-linear changes in memory ability during early childhood. However, the extent to which tasks relate to one another and are indicative of the latent construct of episodic memory is not known. Further, improvements in memory are thought to relate to underlying changes occurring in the functionally distinct subfields of the hippocampus (i.e., CA2-4/dentate gyrus (DG), CA1, and Subiculum) during this developmental period. This study examined changes in episodic memory ability, hippocampal subfield volume, and the relation between changes in episodic memory and volume of hippocampal subfields during early childhood (4 to 8 years) using longitudinal data and a structural equation modeling framework. Results suggest that episodic memory ability improves substantially during this period, with consistent improvements between 4 to 8 years. Further, there are robust increases in subiculum, CA1, and CA2-4/DG volume between 5 to 6 years of age. Finally, within this sample, there were relations between the development of hippocampal subfields and improvements on a single source memory task commonly used to assess episodic memory. Interestingly, this relation was most robust between subiculum and source memory. Overall, these results highlight the ability to use laboratory tasks to characterize developmental changes in episodic memory, highlight 5- to 6-years as a period of developmental change in hippocampal subfields, and further support a role of the hippocampus in supporting episodic memory.

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