Stress Disrupts Human Hippocampal-Prefrontal Function during Prospective Spatial Navigation and Hinders Flexible Behavior

Memory under stress: from adaptation to disorder

Stressful events are ubiquitous in everyday life. The exposure to these stressors initiates the temporally orchestrated release of a multitude of hormones, peptides, and neurotransmitters that target brain areas critically implicated in learning and memory. This review summarizes recent insights on the profound impact of stress on four fundamental processes of memory: memory formation, memory contextualization, memory retrieval, and memory flexibility. Stress mediators instigate dynamic alterations in these processes, facilitating efficient responding under stress and the creation of a decontextualized memory representation that can effectively aid coping with novel future threats. While being generally adaptive, the same stress-related changes may contribute to rigid behaviors, uncontrollable intrusions, or generalized fear responding seen in anxiety disorders or posttraumatic stress disorder (PTSD). Drawing on recent discoveries in cognitive neuroscience and psychiatry, this review discusses how stress-induced alterations in memory processes can simultaneously foster adaptation to stressors and fuel psychopathology. The transition from adaptive to maladaptive changes in the impact of stress on memory hinges on the nuanced interplay of stressor characteristics and individual predispositions. Thus, taking individual differences in the cognitive response to stressors into account is essential for any successful treatment of stress-related mental disorders.

Forming cognitive maps for abstract spaces: the roles of the human hippocampus and orbitofrontal cortex

How does the human brain construct cognitive maps for decision-making and inference? Here, we conduct an fMRI study on a navigation task in multidimensional abstract spaces. Using a deep neural network model, we assess learning levels and categorized paths into exploration and exploitation stages. Univariate analyses show higher activation in the bilateral hippocampus and lateral prefrontal cortex during exploration, positively associated with learning level and response accuracy. Conversely, the bilateral orbitofrontal cortex (OFC) and retrosplenial cortex show higher activation during exploitation, negatively associated with learning level and response accuracy. Representational similarity analysis show that the hippocampus, entorhinal cortex, and OFC more accurately represent destinations in exploitation than exploration stages. These findings highlight the collaboration between the medial temporal lobe and prefrontal cortex in learning abstract space structures. The hippocampus may be involved in spatial memory formation and representation, while the OFC integrates sensory information for decision-making in multidimensional abstract spaces.

Chronic social defeat stress in prairie voles (Microtus ochrogaster): A preclinical model for the study of depression-related phenotypes

BACKGROUND

Stress-induced illnesses, like major depression, are among the leading causes of disability across the world. Consequently, there is a dire need for the validation of translationally-suited animal models incorporating social stress to uncover the etiology of depression. Prairie voles (Microtus ochrogaster) are more translationally relevant than many other rodent models as they display monogamous social and bi-parental behaviors. Therefore, we evaluated whether a novel social defeat stress (SDS) model in male prairie voles induces depression-relevant behavioral outcomes.

METHODS

Adult sexually-naïve male prairie voles experienced SDS bouts from a conspecific pair-bonded male aggressor, 10 min per day for 10 consecutive days. Non-stressed controls (same-sex siblings) were housed in similar conditions but never experienced physical stress. Twenty-four h later, voles were evaluated in social interaction, sucrose preference, and Morris water maze tests - behavioral endpoints validated to assess social withdrawal, anhedonia-related behavior, and spatial memory performance, respectively.

RESULTS

SDS-exposed voles displayed lower sociability and body weight, decreased preference for a sucrose solution, and impairment of spatial memory retrieval. Importantly, no differences in general locomotor activity were observed as a function of SDS exposure.

LIMITATIONS

This study does not include female voles in the experimental design.

CONCLUSIONS

We found that repeated SDS exposure, in male prairie voles, results in a depression-relevant phenotype resembling an anhedonia-like outcome (per reductions in sucrose preference) along with social withdrawal and spatial memory impairment - highlighting that the prairie vole is a valuable model with potential to study the neurobiology of social stress-induced depression-related outcomes.

Stress affects navigation strategies in immersive virtual reality

There are known individual differences in both the ability to learn the layout of novel environments and the flexibility of strategies for navigating known environments. However, it is unclear how navigational abilities are impacted by high-stress scenarios. Here we used immersive virtual reality (VR) to develop a novel behavioral paradigm to examine navigation under dynamically changing situations. We recruited 48 participants (24 female; ages 17-32) to navigate a virtual maze (7.5 m × 7.5 m). Participants learned the maze by moving along a fixed path past the maze's landmarks (paintings). Subsequently, participants experienced either a non-stress condition, or a high-stress condition tasking them with navigating the maze. In the high-stress condition, their initial path was blocked, the environment was darkened, threatening music was played, fog obstructed more distal views of the environment, and participants were given a time limit of 20 s with a countdown timer displayed at the top of their screen. On trials where the path was blocked, we found self-reported stress levels and distance traveled increased while trial completion rate decreased (as compared to non-stressed control trials). On unblocked stress trials, participants were less likely to take a shortcut and consequently navigated less efficiently compared to control trials. Participants with more trait spatial anxiety reported more stress and navigated less efficiently. Overall, our results suggest that navigational abilities change considerably under high-stress conditions.

The mediating role of coping strategies between caregiving burden and pre-death grief among Chinese adult-child caregivers of dementia patients

AIMS

The objective of this study was to examine the relationship between caregiving burden and pre-death grief, with a specific focus on adult-child caregivers in mainland China. Additionally, the study explored whether coping strategies played a mediating role in this correlation.

METHODS

A convenience sample of 320 adult-child caregivers of older parents with dementia from Kunming, mainland China, was recruited for the study. Data were collected using the Chinese version of the Marwit-Meuser Caregiver Grief Inventory-Short Form, the Burden Scale for Family Caregivers, and the Ways of Coping Checklist-Revised.

RESULTS

Results using linear regression and multiple mediation analysis with Hayes' process model indicated that caregiving burden was positively related to pre-death grief and that active coping mediated the relationship between them. In the female group, active coping partially mediated the association between caregiving burden and pre-death grief, but in the male group, this mediating effect did not exist.

CONCLUSION

The study found evidence supporting the link between caregiving burden and pre-death grief among adult-child caregivers of older parents with dementia in mainland China. Furthermore, the caregiving burden prevented the use of active coping, and this decrease in coping increased the perception of pre-death grief. These associations only existed in the female group.

IMPLICATIONS

This paper presented the importance of active coping skills in the dementia caregiving process.

IMPACT

The findings of this study emphasize the necessity for health practitioners to provide targeted interventions regarding pre-death grief among dementia caregivers and strengthen caregivers' active coping strategies to reduce their pre-death grief. Community-based and personal care support services should be promoted to alleviate their caregiving burden.

REPORTING METHOD

We have adhered to the transparent reporting of evaluations with quantitative design statements and the corresponding checklist was followed. PATIENT OR PUBLIC CONTRIBUTION: 'No patient or public involvement'.

Sex-Specific Alterations in Spatial Memory and Hippocampal AKT-mTOR Signaling in Adult Mice Pre-exposed to Ketamine and/or Psychological Stress During Adolescence

Background

Ketamine (KET) is administered to manage major depression in adolescent patients. However, the long-term effects of juvenile KET exposure on memory-related tasks have not been thoroughly assessed. We examined whether exposure to KET, psychological stress, or both results in long-lasting alterations in spatial memory in C57BL/6 mice. Furthermore, we evaluated how KET and/or psychological stress history influenced hippocampal protein kinase B-mechanistic target of rapamycin (AKT-mTOR)-related signaling.

Methods

On postnatal day 35, male and female mice underwent vicarious defeat stress (VDS), a form of psychological stress that reduces sociability in both sexes, with or without KET exposure (20 mg/kg/day, postnatal days 35-44). In adulthood (postnatal day 70), mice were assessed for spatial memory performance on a water maze task or euthanized for hippocampal tissue collection.

Results

Juvenile pre-exposure to KET or VDS individually increased the latency (seconds) to locate the escape platform in adult male, but not female, mice. However, juvenile history of concomitant KET and VDS prevented memory impairment. Furthermore, individual KET or VDS pre-exposure, unlike their combined history, decreased hippocampal AKT-mTOR signaling in adult male mice. Conversely, KET pre-exposure alone increased AKT-mTOR in the hippocampus of adult female mice. Lastly, rapamycin-induced decreases of mTOR in naïve adult female mice induced spatial memory retrieval deficits, mimicking adult male mice with a history of exposure to VDS or KET.

Conclusions

Our preclinical model shows how KET treatment for the management of adolescent psychological stress-induced sequelae does not impair spatial memory later in life. However, juvenile recreational KET misuse, like psychological stress history, results in long-term spatial memory deficits and hippocampal AKT-mTOR signaling changes in a sex-specific manner.

Effects of Psychological Interventions on Performance Anxiety in Performing Artists and Athletes: A Systematic Review with Meta-Analysis

Levels of state and trait anxiety are relevant for performing artists and professional athletes to obtain optimal performance outcomes. However, evidence-based knowledge regarding the effectiveness of psychological interventions on performance anxiety is currently minimal. Thus, the objective of this systematic review with meta-analysis was to characterize, aggregate, and quantify intervention effects on measures of state and trait performance anxiety in performing artists and professional athletes. A systematic search of the literature according to the PRISMA guidelines was conducted on the databases PubMed, Medline, SPORTDiscus, PsycInfo, Embase, and Web of Science from 1 January 1960 to 9 November 2022. The search only included controlled studies employing pre-post measures and excluded performing arts fields that do not depend on fine motor skills. Initially, 1022 articles were identified; after removing duplicates and assessing abstracts and full texts, 20 articles were used to calculate weighted standardized mean differences (SMDs). In terms of state performance anxiety, our results revealed a large overall effect (SMD = 0.88), a medium effect (SMD = 0.62) for studies using scales with total scores (i.e., MPAI-A, STAI), and large effects (cognitive anxiety: SMD = 0.93, somatic anxiety: SMD = 0.92, self-confidence: SMD = 0.97) for studies applying scales with sub-scores (i.e., CSAI-2R)-all in favour of the intervention groups. Regarding trait performance anxiety (e.g., SCAT), we detected a small effect (SMD = 0.32), also favouring the intervention groups. Interventions to reduce performance anxiety in performing artists and professional athletes revealed varying levels of effectiveness ranging from small (trait) to large (state). Therefore, future studies should investigate modalities to increase intervention efficacy, especially for the small-sized changes in trait performance anxiety.

Neurocognitive Model of Schema-Congruent and -Incongruent Learning in Clinical Disorders: Application to Social Anxiety and Beyond

Negative schemas lie at the core of many common and debilitating mental disorders. Thus, intervention scientists and clinicians have long recognized the importance of designing effective interventions that target schema change. Here, we suggest that the optimal development and administration of such interventions can benefit from a framework outlining how schema change occurs in the brain. Guided by basic neuroscientific findings, we provide a memory-based neurocognitive framework for conceptualizing how schemas emerge and change over time and how they can be modified during psychological treatment of clinical disorders. We highlight the critical roles of the hippocampus, ventromedial prefrontal cortex, amygdala, and posterior neocortex in directing schema-congruent and -incongruent learning (SCIL) in the interactive neural network that comprises the autobiographical memory system. We then use this framework, which we call the SCIL model, to derive new insights about the optimal design features of clinical interventions that aim to strengthen or weaken schema-based knowledge through the core processes of episodic mental simulation and prediction error. Finally, we examine clinical applications of the SCIL model to schema-change interventions in psychotherapy and provide cognitive-behavior therapy for social anxiety disorder as an illustrative example.

Vestibular perceptual testing from lab to clinic: a review

Not all dizziness presents as vertigo, suggesting other perceptual symptoms for individuals with vestibular disease. These non-specific perceptual complaints of dizziness have led to a recent resurgence in literature examining vestibular perceptual testing with the aim to enhance clinical diagnostics and therapeutics. Recent evidence supports incorporating rehabilitation methods to retrain vestibular perception. This review describes the current field of vestibular perceptual testing from scientific laboratory techniques that may not be clinic friendly to some low-tech options that may be more clinic friendly. Limitations are highlighted suggesting directions for additional research.

Motivation moderates gender differences in navigation performance

Gender differences in navigation performance are a recurrent and controversial topic. Previous research suggests that men outperform women in navigation tasks and that men and women exhibit different navigation strategies. Here, we investigate whether motivation to complete the task moderates the relationship between navigation performance and gender. Participants learned the locations of landmarks in a novel virtual city. During learning, participants could trigger a top-down map that depicted their current position and the locations of the landmarks. During testing, participants were divided into control and treatment groups and were not allowed to consult the map. All participants were given 16 minutes to navigate to the landmarks, but those in the treatment group were monetarily penalized for every second they spent completing the task. Results revealed a negative relationship between physiological arousal and the time required to locate the landmarks. In addition, gender differences in strategy were found during learning, with women spending more time with the map and taking 40% longer than men to locate the landmarks. Interestingly, an interaction between gender and treatment group revealed that women in the control group required more time than men and women in the treatment group to retrieve the landmarks. During testing, women in the control group also took more circuitous routes compared to men in the control group and women in the treatment group. These results suggest that a concurrent and relevant stressor can motivate women to perform similarly to men, helping to diminish pervasive gender differences found in the navigation literature.

Acute stress impairs visual path integration

Acute stress exerts substantial effects on episodic memory, which are often mediated by glucocorticoids, the end-product of the hypothalamic-pituitary-adrenal axis. Surprisingly little is known, however, about the influence of acute stress on human spatial navigation. One specific navigational strategy is path integration, which is linked to the medial entorhinal cortex, a region harboring glucocorticoid receptors and thus susceptible for stress effects. Here, we investigated effects of acute stress on path integration performance using a virtual homing task. We divided a sample of healthy young male participants into a stress group (nstress = 32) and a control group (ncontrol = 34). The stress group underwent the socially evaluated cold-pressor test, while the control group underwent a non-stressful control procedure. Stress induction was confirmed via physiological and subjective markers, including an increase of salivary cortisol concentrations. We applied linear mixed models to investigate the effect of acute stress on path integration depending on task difficulty and the presence or absence of spatial cues. These analyses revealed that stress impaired path integration especially in trials with high difficulty and led to greater decline of performance upon removal of spatial cues. Stress-induced deficits were strongly related to impaired distance estimation, and to a lesser extent to compromised rotation estimation. These behavioral findings are in accordance with the hypothesis that acute stress impairs path integration processes, potentially by affecting the entorhinal grid cell system. More generally, the current data suggests acute stress to impair cognitive functions mediated by medial temporal lobe regions outside the hippocampus.

Neurocognitive effects of stress: a metaparadigm perspective

Stressful experiences, both physical and psychological, that are overwhelming (i.e., inescapable and unpredictable), can measurably affect subsequent neuronal properties and cognitive functioning of the hippocampus. At the cellular level, stress has been shown to alter hippocampal synaptic plasticity, spike and local field potential activity, dendritic morphology, neurogenesis, and neurodegeneration. At the behavioral level, stress has been found to impair learning and memory for declarative (or explicit) tasks that are based on cognition, such as verbal recall memory in humans and spatial memory in rodents, while facilitating those that are based on emotion, such as differential fear conditioning in humans and contextual fear conditioning in rodents. These vertically related alterations in the hippocampus, procedurally observed after subjects have undergone stress, are generally believed to be mediated by recurrently elevated circulating hypothalamic-pituitary-adrenal (HPA) axis effector hormones, glucocorticoids, directly acting on hippocampal neurons densely populated with corticosteroid receptors. The main purposes of this review are to (i) provide a synopsis of the neurocognitive effects of stress in a historical context that led to the contemporary HPA axis dogma of basic and translational stress research, (ii) critically reappraise the necessity and sufficiency of the glucocorticoid hypothesis of stress, and (iii) suggest an alternative metaparadigm approach to monitor and manipulate the progression of stress effects at the neural coding level. Real-time analyses can reveal neural activity markers of stress in the hippocampus that can be used to extrapolate neurocognitive effects across a range of stress paradigms (i.e., resolve scaling and dichotomous memory effects issues) and understand individual differences, thereby providing a novel neurophysiological scaffold for advancing future stress research.

Spatial navigation under threat: aversive apprehensions improve route retracing in higher versus lower trait anxious individuals

Spatial navigation is a basic function for survival, and the ability to retrace a route has direct relevance for avoiding dangerous places. This study investigates the effects of aversive apprehensions on spatial navigation in a virtual urban environment. Healthy participants with varying degrees of trait anxiety performed a route-repetition and a route-retracing task under threatening and safe context conditions. Results reveal an interaction between the effect of threatening/safe environments and trait anxiety: while threat impairs route-retracing in lower-anxious individuals, this navigational skill is boosted in higher-anxious individuals. According to attentional control theory, this finding can be explained by an attentional shift toward information relevant for intuitive coping strategies (i.e., running away), which should be more pronounced in higher-anxious individuals. On a broader scale, our results demonstrate an often-neglected advantage of trait anxiety, namely that it promotes the processing of environmental information relevant for coping strategies and thus prepares the organism for adequate flight responses.

Neural Index of Reinforcement Learning Predicts Improved Stimulus-Response Retention under High Working Memory Load

Human learning and decision-making are supported by multiple systems operating in parallel. Recent studies isolating the contributions of reinforcement learning (RL) and working memory (WM) have revealed a trade-off between the two. An interactive WM/RL computational model predicts that although high WM load slows behavioral acquisition, it also induces larger prediction errors in the RL system that enhance robustness and retention of learned behaviors. Here, we tested this account by parametrically manipulating WM load during RL in conjunction with EEG in both male and female participants and administered two surprise memory tests. We further leveraged single-trial decoding of EEG signatures of RL and WM to determine whether their interaction predicted robust retention. Consistent with the model, behavioral learning was slower for associations acquired under higher load but showed parametrically improved future retention. This paradoxical result was mirrored by EEG indices of RL, which were strengthened under higher WM loads and predictive of more robust future behavioral retention of learned stimulus-response contingencies. We further tested whether stress alters the ability to shift between the two systems strategically to maximize immediate learning versus retention of information and found that induced stress had only a limited effect on this trade-off. The present results offer a deeper understanding of the cooperative interaction between WM and RL and show that relying on WM can benefit the rapid acquisition of choice behavior during learning but impairs retention.SIGNIFICANCE STATEMENT Successful learning is achieved by the joint contribution of the dopaminergic RL system and WM. The cooperative WM/RL model was productive in improving our understanding of the interplay between the two systems during learning, demonstrating that reliance on RL computations is modulated by WM load. However, the role of WM/RL systems in the retention of learned stimulus-response associations remained unestablished. Our results show that increased neural signatures of learning, indicative of greater RL computation, under high WM load also predicted better stimulus-response retention. This result supports a trade-off between the two systems, where degraded WM increases RL processing, which improves retention. Notably, we show that this cooperative interplay remains largely unaffected by acute stress.

Entropy and a sub-group of geometric measures of paths predict the navigability of an environment

Despite extensive research on navigation, it remains unclear which features of an environment predict how difficult it will be to navigate. We analysed 478,170 trajectories from 10,626 participants who navigated 45 virtual environments in the research app-based game Sea Hero Quest. Virtual environments were designed to vary in a range of properties such as their layout, number of goals, visibility (varying fog) and map condition. We calculated 58 spatial measures grouped into four families: task-specific metrics, space syntax configurational metrics, space syntax geometric metrics, and general geometric metrics. We used Lasso, a variable selection method, to select the most predictive measures of navigation difficulty. Geometric features such as entropy, area of navigable space, number of rings and closeness centrality of path networks were among the most significant factors determining the navigational difficulty. By contrast a range of other measures did not predict difficulty, including measures of intelligibility. Unsurprisingly, other task-specific features (e.g. number of destinations) and fog also predicted navigation difficulty. These findings have implications for the study of spatial behaviour in ecological settings, as well as predicting human movements in different settings, such as complex buildings and transport networks and may aid the design of more navigable environments.

Chronic stress is associated with specific path integration deficits

Repeated exposure to stress (chronic stress) can cause excess levels of circulating cortisol and has detrimental influences on various cognitive functions including long-term memory and navigation. However, it remains an open question whether chronic stress affects path integration, a navigational strategy that presumably relies on the functioning of grid cells in the medial entorhinal cortex. The entorhinal cortex is a brain region in the medial temporal lobe, which contains multiple cell types involved in spatial navigation (and episodic memory), and a high number of corticosteroid receptors, predisposing it as a potential target of cortisol effects. Here, our goal was to investigate the association between chronic stress and path integration performance. We assessed chronic stress via hair cortisol concentration (physiological measure) and the Perceived Stress Questionnaire (subjective measure) in 52 female participants aged 22-65 years. Path integration was measured using a virtual homing task. Linear mixed models revealed selective impairments associated with chronic stress that depended on error type and environmental features. When focusing on distance estimations in the path integration task, we observed a significant relationship to hair cortisol concentrations indicating impaired path integration particularly during trials with higher difficulty in participants with high hair cortisol concentrations. This relationship especially emerged in the absence of spatial cues (a boundary or a landmark), and particularly in participants who reported high levels of subjectively experienced chronic stress. The findings are in line with the hypothesis that chronic stress compromises path integration, possibly via an effect on the entorhinal grid cell system.

Effects of Acute Stress on Rigid Learning, Flexible Learning, and Value-Based Decision-Making in Spatial Navigation

The current study investigated how stress affects value-based decision-making during spatial navigation and different types of learning underlying decisions. Eighty-two adult participants (42 females) first learned to find object locations in a virtual environment from a fixed starting location (rigid learning) and then to find the same objects from unpredictable starting locations (flexible learning). Participants then decided whether to reach goal objects from the fixed or unpredictable starting location. We found that stress impairs rigid learning in females, and it does not impair, and even improves, flexible learning when performance with rigid learning is controlled for. Critically, examining how earlier learning influences subsequent decision-making using computational models, we found that stress reduces memory integration, making participants more likely to focus on recent memory and less likely to integrate information from other sources. Collectively, our results show how stress impacts different memory systems and the communication between memory and decision-making.

Planes, Trains, and Automobiles: Commuting in the 2020s and Beyond

In this introduction to the special issue about commuting, we invite readers to consider how this frequently occurring worker activity should be integrated and investigated within the organizational sciences. Commuting is ubiquitous in organizational life. Yet, despite this centrality, it remains one of the most understudied topics in the organizational sciences. This special issue seeks to remedy this oversight by introducing seven articles that review the literature, identify knowledge gaps, theorize through an organization science lens, and provide directions for future research. We introduce these seven articles by discussing how they address three cross-cutting themes (Challenging the Status Quo, Insights into the Commuting Experience, The Future of Commuting). We hope that the work within this special issue informs and inspires organizational scholars to engage in meaningful interdisciplinary research on commuting going forward.

Toward an Understanding of Cognitive Mapping Ability Through Manipulations and Measurement of Schemas and Stress

Daily function depends on an ability to mentally map our environment. Environmental factors such as visibility and layout, and internal factors such as psychological stress, can challenge spatial memory and efficient navigation. Importantly, people vary dramatically in their ability to navigate flexibly and overcome such challenges. In this paper, we present an overview of "schema theory" and our view of its relevance to navigational memory research. We review several studies from our group and others, that integrate manipulations of environmental complexity and affective state in order to gain a richer understanding of the mechanisms that underlie individual differences in navigational memory. Our most recent data explicitly link such individual differences to ideas rooted in schema theory, and we discuss the potential for this work to advance our understanding of cognitive decline with aging. The data from this body of work highlight the powerful impacts of individual cognitive traits and affective states on the way people take advantage of environmental features and adopt navigational strategies.

Understanding Differences in Wayfinding Strategies

Navigating to goal locations in a known environment (wayfinding) can be accomplished by different strategies, notably by taking habitual, well-learned routes (response strategy) or by inferring novel paths, such as shortcuts, from spatial knowledge of the environment's layout (place strategy). Human and animal neuroscience studies reveal that these strategies reflect different brain systems, with response strategies relying more on activation of the striatum and place strategies associated with activation of the hippocampus. In addition to individual differences in strategy, recent behavioral studies show sex differences such that men use place strategies more than women, and age differences such that older adults use more response strategies than younger adults. This paper takes a comprehensive multilevel approach to understanding these differences, characterizing wayfinding as a complex information processing task. This analysis reveals factors that affect navigation strategy, including availability of the relevant type of environmental knowledge, momentary access to this knowledge, trade-offs between physical and mental effort in different navigation contexts, and risk taking. We consider how strategies are influenced by the computational demands of a navigation task and by factors that affect the neural circuits underlying navigation. We also discuss limitations of laboratory studies to date and outline priorities for future research, including relating wayfinding strategies to independent measures of spatial knowledge, and studying wayfinding strategies in naturalistic environments.

Building a Cognitive Science of Human Variation: Individual Differences in Spatial Navigation

The aim of this issue is to take stock of cognitive science of human variation in the field of spatial navigation, an important domain in which debates have often assumed an invariant human mind. Addressing the challenge of individual differences requires cognitive scientists to change their practices in several ways. First, we need to consider how to design measures and paradigms that have adequate psychometric characteristics. Second, using reliable, efficient, and valid measures, we need to examine how people vary from time to time, both in the short run due to emotions, such as stress or time pressure, and in the longer run, due to training or living in physical environments that require wayfinding skills. Third, we need to study people different from the traditional college participants, including variations in age, gender, education, culture, physical environment, and possible interactions among these variables.

On the proposed role of metacognition in environment learning: recommendations for research

Metacognition plays a role in environment learning (EL). When navigating, we monitor environment information to judge our likelihood to remember our way, and we engage in control by using tools to prevent getting lost. Yet, the relationship between metacognition and EL is understudied. In this paper, we examine the possibility of leveraging metacognition to support EL. However, traditional metacognitive theories and methodologies were not developed with EL in mind. Here, we use traditional metacognitive theories and approaches as a foundation for a new examination of metacognition in EL. We highlight three critical considerations about EL. Namely: (1) EL is a complex process that unfolds sequentially and is thereby enriched with multiple different types of cues, (2) EL is inherently driven by a series of ecologically relevant motivations and constraints, and (3) monitoring and control interact to support EL. In doing so, we describe how task demands and learning motivations inherent to EL should shape how metacognition is explored. With these considerations, we provide three methodological recommendations for investigating metacognition during EL. Specifically, researchers should: (1) instantiate EL goals to impact learning, metacognition, and retrieval processes, (2) prompt learners to make frequent metacognitive judgments and consider metacognitive accuracy as a primary performance metric, and (3) incorporate insights from both transfer appropriate processing and monitoring hypotheses when designing EL assessments. In summary, to effectively investigate how metacognition impacts EL, both ecological and methodological considerations need to be weighed.

How Imagination and Memory Shape the Moral Mind

Interdisciplinary research has proposed a multifaceted view of human cognition and morality, establishing that inputs from multiple cognitive and affective processes guide moral decisions. However, extant work on moral cognition has largely overlooked the contributions of episodic representation. The ability to remember or imagine a specific moment in time plays a broadly influential role in cognition and behavior. Yet, existing research has only begun exploring the influence of episodic representation on moral cognition. Here, we evaluate the theoretical connections between episodic representation and moral cognition, review emerging empirical work revealing how episodic representation affects moral decision-making, and conclude by highlighting gaps in the literature and open questions. We argue that a comprehensive model of moral cognition will require including the episodic memory system, further delineating its direct influence on moral thought, and better understanding its interactions with other mental processes to fundamentally shape our sense of right and wrong.

A comparison of reinforcement learning models of human spatial navigation

Reinforcement learning (RL) models have been influential in characterizing human learning and decision making, but few studies apply them to characterizing human spatial navigation and even fewer systematically compare RL models under different navigation requirements. Because RL can characterize one's learning strategies quantitatively and in a continuous manner, and one's consistency of using such strategies, it can provide a novel and important perspective for understanding the marked individual differences in human navigation and disentangle navigation strategies from navigation performance. One-hundred and fourteen participants completed wayfinding tasks in a virtual environment where different phases manipulated navigation requirements. We compared performance of five RL models (3 model-free, 1 model-based and 1 "hybrid") at fitting navigation behaviors in different phases. Supporting implications from prior literature, the hybrid model provided the best fit regardless of navigation requirements, suggesting the majority of participants rely on a blend of model-free (route-following) and model-based (cognitive mapping) learning in such navigation scenarios. Furthermore, consistent with a key prediction, there was a correlation in the hybrid model between the weight on model-based learning (i.e., navigation strategy) and the navigator's exploration vs. exploitation tendency (i.e., consistency of using such navigation strategy), which was modulated by navigation task requirements. Together, we not only show how computational findings from RL align with the spatial navigation literature, but also reveal how the relationship between navigation strategy and a person's consistency using such strategies changes as navigation requirements change.

Predictive maps in rats and humans for spatial navigation

Much of our understanding of navigation comes from the study of individual species, often with specific tasks tailored to those species. Here, we provide a novel experimental and analytic framework integrating across humans, rats, and simulated reinforcement learning (RL) agents to interrogate the dynamics of behavior during spatial navigation. We developed a novel open-field navigation task ("Tartarus maze") requiring dynamic adaptation (shortcuts and detours) to frequently changing obstructions on the path to a hidden goal. Humans and rats were remarkably similar in their trajectories. Both species showed the greatest similarity to RL agents utilizing a "successor representation," which creates a predictive map. Humans also displayed trajectory features similar to model-based RL agents, which implemented an optimal tree-search planning procedure. Our results help refine models seeking to explain mammalian navigation in dynamic environments and highlight the utility of modeling the behavior of different species to uncover the shared mechanisms that support behavior.

Environmental overlap influences goal-oriented coding of spatial sequences differently along the long-axis of hippocampus

When navigating our world we often first plan or retrieve a route to our goal, avoiding alternative paths to other destinations. Inspired by computational and animal models, we have recently demonstrated evidence that the human hippocampus supports prospective spatial coding, mediated by interactions with the prefrontal cortex. But the relationship between such signals and the need to discriminate possible routes based on their goal remains unclear. In the current study, we combined human fMRI, multi-voxel pattern analysis, and an established paradigm for contrasting memories of nonoverlapping routes with those of routes that cross paths and must be disambiguated. By classifying goal-oriented representations at the initiation of a navigational route, we demonstrate that environmental overlap modulates goal-oriented representations in the hippocampus. This modulation manifest through representational shifts from posterior to anterior components of the right hippocampus. Moreover, declines in goal-oriented decoding due to overlapping memories were predicted by the strength of the alternative memory, suggesting co-expression and competition between alternatives in the hippocampus during prospective thought. Moreover, exploratory whole-brain analyses revealed that a region of frontopolar cortex, which we have previously tied to prospective route planning, represented goal-states in new overlapping routes. Together, our findings provide insight into the influences of contextual overlap on the long-axis of the hippocampus and a broader memory and planning network that we have long-associated with such navigation tasks.

Mechanisms of memory under stress

It is well established that stress has a major impact on memory, driven by the concerted action of various stress mediators on the brain. Recent years, however, have seen considerable advances in our understanding of the cellular, neural network, and cognitive mechanisms through which stress alters memory. These novel insights highlight the intricate interplay of multiple stress mediators, including-beyond corticosteroids, catecholamines, and peptides-for instance, endocannabinoids, which results in time-dependent shifts in large-scale neural networks. Such stress-induced network shifts enable highly specific memories of the stressful experience in the long run at the cost of transient impairments in mnemonic flexibility during and shortly after a stressful event. Based on these recent discoveries, we provide a new integrative framework that links the cellular, systems, and cognitive mechanisms underlying acute stress effects on memory processes and points to potential targets for treating aberrant memory in stress-related mental disorders.

Distinct medial-tempora lobe mechanisms of encoding and amygdala-mediated memory reinstatement for disgust and fear

Current models of episodic memory posit that retrieval involves the reenactment of encoding processes. Recent evidence has shown that this reinstatement process - indexed by subsequent encoding-retrieval similarity of brain activity patterns - is related to the activity in the hippocampus during encoding. However, we tend to re-experience emotional events in memory more richly than dull events. The role of amygdala - a critical hub of emotion processing - in reinstatement of emotional events was poorly understood. To investigate it, we leveraged a previously overlooked divergence in the role of amygdala in memory modulation by distinct emotions - disgust and fear. Here we used a novel paradigm in which participants encoded complex events (word pairs) and their memory was tested after 3 weeks, both phases during fMRI scanning. Using representational similarity analysis and univariate analyses, we show that the strength of amygdala activation during encoding was correlated with memory reinstatement of individual event representations in emotion-specific regions. Critically, amygdala modulated reinstatement more for disgust than fear. This was in line with other differences observed at the level of memory performance and neural mechanisms of encoding. Specifically, amygdala and perirhinal cortex were more involved during encoding of disgust-related events, whereas hippocampus and parahippocampal gyrus during encoding of fear-related events. Together, these findings shed a new light on the role of the amygdala and medial temporal lobe regions in encoding and reinstatement of specific emotional memories.

How anxiety predicts interpersonal curiosity during the COVID-19 pandemic: The mediation effect of interpersonal distancing and autistic tendency

With the worldwide implementation of quarantine regulations to suppress the spread of the COVID-19, anxiety, interpersonal distancing and autistic tendency may decrease individuals' desire to seek interpersonal information and thus might have negative effects on their interpersonal curiosity. Through behavioral paradigms and scales, two studies were conducted (Study 1: n = 570; Study 2: n = 501). We explored the predictive effect of anxiety on interpersonal curiosity in situations when mandatory isolation measures have led to dramatic changes in interpersonal distancing and autistic tendency. We found that interpersonal distancing and autistic tendency negatively predicted interpersonal curiosity, and these predictive effects suppressed the positive prediction of state anxiety to interpersonal curiosity. Our research provides insights into the relationships among anxiety, curiosity, interpersonal distancing, and autistic tendency during the COVID-19 pandemic.

Evidence for a gradient within the medial temporal lobes for flexible retrieval under hierarchical task rules

A fundamental question in memory research is how the hippocampus processes contextual cues to retrieve distinct mnemonic associations. Prior research has emphasized the importance of hippocampal-prefrontal interactions for context-dependent memory. Our fMRI study examined the human medial temporal lobes (MTL) and their prefrontal interactions when retrieving memories associated with hierarchically organized task contexts. Participants learned virtual object-location associations governed by subordinate and superordinate task rules, which could be independently cued to change. On each fMRI trial, participants retrieved the correct object for convergent rule and location contextual information. Results demonstrated that hippocampal activity and hippocampal-prefrontal functional interconnectivity distinguished retrieval under different levels of hierarchically organized task rules. In explicit contrast to the hippocampal tail, anterior (body and head) regions were recruited specifically for superordinate changes in the contextual hierarchy. The hippocampal body also differed in its functional connectivity with the prefrontal cortex for superordinate versus subordinate changes. Our findings demonstrate a gradient in MTL for associative retrieval under changing task rules, and advance understanding of hippocampal-prefrontal interactions that support flexible contextual memory.

Hippocampal volume and navigational ability: The map(ping) is not to scale

A critical question regards the neural basis of complex cognitive skill acquisition. One extensively studied skill is navigation, with evidence suggesting that humans vary widely in navigation abilities. Yet, data supporting the neural underpinning of these individual differences are mixed. Some evidence suggests robust structure-behavior relations between hippocampal volume and navigation ability, whereas other experiments show no such correlation. We focus on several possibilities for these discrepancies: 1) volumetric hippocampal changes are relevant only at the extreme ranges of navigational abilities; 2) hippocampal volume correlates across individuals but only for specific measures of navigation skill; 3) hippocampal volume itself does not correlate with navigation skill acquisition; connectivity patterns are more relevant. To explore this third possibility, we present a model emphasizing functional connectivity changes, particularly to extra-hippocampal structures. This class of models arises from the premise that navigation is dynamic and that good navigators flexibly solve spatial challenges. These models pave the way for research on other skills and provide more precise predictions for the neural basis of skill acquisition.

Behavioural and cognitive mechanisms of Developmental Topographical Disorientation

Individuals affected by Developmental Topographical Disorientation (DTD) get lost on a daily basis, even in the most familiar of surroundings such as their neighbourhood, the building where they have worked for many years, and, in extreme cases, even in their own homes. Individuals with DTD report a lifelong selective inability to orient despite otherwise well-preserved general cognitive functions, and the absence of any acquired brain injury or neurological condition, with general intelligence reported to be within the normal range. To date, the mechanisms underlying such a selective developmental condition remain unknown. Here, we report the findings of a 10-year-long study investigating the behavioural and cognitive mechanisms of DTD in a large sample of 1211 cases. We describe the demographics, heritability pattern, self-reported and objective spatial abilities, and some personality traits of individuals with DTD as compared to a sample of 1624 healthy controls; importantly, we test the specific hypothesis that the presence of DTD is significantly related to the inability of the individuals to form a mental representation of the spatial surroundings (i.e., a cognitive map). We found that individuals with DTD reported relatively greater levels of neuroticism and negative affect, and rated themselves more poorly on self-report measures of memory and imagery skills related to objects, faces, and places. While performing interactive tasks, as a group, the individuals with DTD performed slightly worse on a scene-based perspective-taking task, and, notably struggled to solve tasks that demand the generation and use of a cognitive map. These novel findings help define the phenotype of DTD, and lay the foundation for future studies of the neurological and genetic mechanisms of this lifelong condition.

A Translational Paradigm to Study the Effects of Uncontrollable Stress in Humans

Theories on the aetiology of depression in humans are intimately linked to animal research on stressor controllability effects. However, explicit translations of established animal designs are lacking. In two consecutive studies, we developed a translational paradigm to study stressor controllability effects in humans. In the first study, we compared three groups of participants, one exposed to escapable stress, one yoked inescapable stress group, and a control group not exposed to stress. Although group differences indicated successful stress induction, the manipulation failed to differentiate groups according to controllability. In the second study, we employed an improved paradigm and contrasted only an escapable stress group to a yoked inescapable stress group. The final design successfully induced differential effects on self-reported perceived control, exhaustion, helplessness, and behavioural indices of adaptation to stress. The latter were examined in a new escape behaviour test which was modelled after the classic shuttle box animal paradigm. Contrary to the learned helplessness literature, exposure to uncontrollable stress led to more activity and exploration; however, these behaviours were ultimately not adaptive. We discuss the results and possible applications in light of the findings on learning and agency beliefs, inter-individual differences, and interventions aimed at improving resilience to stress-induced mental dysfunction.