Stress and multiple memory systems: from ‘thinking’ to ‘doing’

Hippocampus and striatum show distinct contributions to longitudinal changes in value-based learning in middle childhood

The hippocampal-dependent memory system and striatal-dependent memory system modulate reinforcement learning depending on feedback timing in adults, but their contributions during development remain unclear. In a 2-year longitudinal study, 6-to-7-year-old children performed a reinforcement learning task in which they received feedback immediately or with a short delay following their response. Children's learning was found to be sensitive to feedback timing modulations in their reaction time and inverse temperature parameter, which quantifies value-guided decision-making. They showed longitudinal improvements towards more optimal value-based learning, and their hippocampal volume showed protracted maturation. Better delayed model-derived learning covaried with larger hippocampal volume longitudinally, in line with the adult literature. In contrast, a larger striatal volume in children was associated with both better immediate and delayed model-derived learning longitudinally. These findings show, for the first time, an early hippocampal contribution to the dynamic development of reinforcement learning in middle childhood, with neurally less differentiated and more cooperative memory systems than in adults.

The effects of yohimbine and hydrocortisone on selective attention to fearful faces: An fMRI study

INTRODUCTION

Selective attention to salient emotional information can enable an advantage in the face of danger. The present study aims to investigate the influence of the stress neuromodulators, norepinephrine and cortisol, on selective attention processes to fearful faces and its neuronal activation.

METHODS AND MATERIALS

We used a randomized, double-blind, placebo-controlled design. 167 healthy men between 18 and 35 years (mean [SD] age: 25.23 [4.24] years) participated in the study. Participants received either: (A) yohimbine (n= 41), (B) hydrocortisone (n = 41), (C) yohimbine and hydrocortisone (n = 42) or (D) placebo only (n= 43) and participated in a dot-probe task with fearful and neutral faces in an fMRI scanner.

RESULTS

We found an attentional bias toward fearful faces across all groups and related neuronal activation in the left cuneus. We did not find any differences between experimental treatment groups in selective attention and its neuronal activation.

DISCUSSION

Our results provide evidence that fearful faces lead to an attentional bias with related neuronal activation in the left cuneus. We did not replicate formerly reported activation in the amygdala, intraparietal sulcus, dorsal anterior cingulate cortex, and thalamus. Suitability of the dot-probe task for fMRI studies and insignificant treatment effects are discussed.

Class I histone deacetylases inhibition reverses memory impairment induced by acute stress in mice

While chronic stress induces learning and memory impairments, acute stress may facilitate or prevent memory consolidation depending on whether it occurs during the learning event or before it, respectively. On the other hand, it has been shown that histone acetylation regulates long-term memory formation. This study aimed to evaluate the effect of two inhibitors of class I histone deacetylases (HDACs), 4-phenylbutyrate (PB) and IN14 (100 mg/kg/day, ip for 2 days), on memory performance in mice exposed to a single 15-min forced swimming stress session. Plasma corticosterone levels were determined 30 minutes after acute swim stress in one group of mice. In another experimental series, independent groups of mice were trained in one of three different memory tasks: Object recognition test, Elevated T maze, and Buried food location test. Subsequently, the hippocampi were removed to perform ELISA assays for histone deacetylase 2 (HDAC2) expression. Acute stress induced an increase in plasma corticosterone levels, as well as hippocampal HDAC2 content, along with an impaired performance in memory tests. Moreover, PB and IN14 treatment prevented memory loss in stressed mice. These findings suggest that HDAC2 is involved in acute stress-induced cognitive impairment. None of the drugs improved memory in non-stressed animals, indicating that HDACs inhibitors are not cognitive boosters, but rather potentially useful drugs for mitigating memory deficits.

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.

Acute Stress Enhances Memory and Preference for Smoking-Related Associations in Smokers

INTRODUCTION

Nicotine dependence follows a chronic course that is characterized by repeated relapse, often driven by acute stress and rewarding memories of smoking retrieved from related contexts. These two triggers can also interact, with stress influencing retrieval of contextual memories. However, the roles of these processes in nicotine dependence remain unknown.

AIMS AND METHODS

We investigated how acute stress biases memory for smoking-associated contexts among smokers (N = 65) using a novel laboratory paradigm. On day 1, participants formed associations between visual stimuli of items (either neutral or related to smoking) and places (background scenes). On day 2 (24 hours later), participants were exposed to an acute laboratory-based stressor (socially evaluated cold pressor test; N = 32) or a matched control condition (N = 33) prior to being tested on their memory recognition and preferences for each item and place. We distinguished the accuracy of memory into specific (ie, precisely correct) or gist (ie, lure items with similar content) categories.

RESULTS

Results demonstrated that the stressor significantly induced physiological and subjective perceived stress responses, and that stressed smokers exhibited a memory bias in favor of smoking-related items. In addition, the stressed group displayed greater preference for both smoking-related items and places that had been paired with the smoking-related items. We also found suggestive evidence that stronger smoking-related memory biases were associated with more severe nicotine dependence (ie, years of smoking).

CONCLUSIONS

These results highlight the role of stress in biasing smokers toward remembering contexts associated with smoking, and amplifying their preference for these contexts.

IMPLICATIONS

The current study elucidates the role of acute stress in promoting memory biases favoring smoking-related associations among smokers. The results suggest that the retrieval of smoking-biased associative memory could be a crucial factor in stress-related nicotine seeking. This may lead to a potential intervention targeting the extinction of smoking-related context memories as a preventive strategy for stress-induced relapse.

Does stress induction affect cognitive performance or avoidance of cognitive effort?

Previous research has shown that acute psychosocial stress impairs cognitive abilities, but recent studies suggest that this may be due to a decrease in willingness to engage in cognitive effort rather than a direct effect on performance. The aim of the present study was to replicate this last research and verify the influence of acute stress on avoidance of cognitive effort and cognitive performance. Fifty young, healthy individuals (26 females, 24 males) aged between 18 and 40 years were randomly assigned to two groups: a stress condition and a control condition. We used a Demand Selection Task paradigm (DST), in which participants chose between performing tasks that required either high or low cognitive effort. Stress was induced through the Trier Social Stress Test (TSST) and measured with both subjective and psychophysiological measurements. The results indicated that acute stress significantly increased participants' preference for less demanding behaviors, while no significant alterations in cognitive performance in task change activities were found. This study offers new perspectives on how stress affects behavior and decision-making in everyday life.

Targeting Human Glucocorticoid Receptors in Fear Learning: A Multiscale Integrated Approach to Study Functional Connectivity

Fear extinction is a phenomenon that involves a gradual reduction in conditioned fear responses through repeated exposure to fear-inducing cues. Functional brain connectivity assessments, such as functional magnetic resonance imaging (fMRI), provide valuable insights into how brain regions communicate during these processes. Stress, a ubiquitous aspect of life, influences fear learning and extinction by changing the activity of the amygdala, prefrontal cortex, and hippocampus, leading to enhanced fear responses and/or impaired extinction. Glucocorticoid receptors (GRs) are key to the stress response and show a dual function in fear regulation: while they enhance the consolidation of fear memories, they also facilitate extinction. Accordingly, GR dysregulation is associated with anxiety and mood disorders. Recent advancements in cognitive neuroscience underscore the need for a comprehensive understanding that integrates perspectives from the molecular, cellular, and systems levels. In particular, neuropharmacology provides valuable insights into neurotransmitter and receptor systems, aiding the investigation of mechanisms underlying fear regulation and potential therapeutic targets. A notable player in this context is cortisol, a key stress hormone, which significantly influences both fear memory reconsolidation and extinction processes. Gaining a thorough understanding of these intricate interactions has implications in terms of addressing psychiatric disorders related to stress. This review sheds light on the complex interactions between cognitive processes, emotions, and their neural bases. In this endeavor, our aim is to reshape the comprehension of fear, stress, and their implications for emotional well-being, ultimately aiding in the development of therapeutic interventions.

Do non-traumatic stressful life events and ageing negatively impact working memory performance and do they interact to further impair working memory performance?

Stress and normal ageing produce allostatic load, which may lead to difficulties with cognition thereby degrading quality of life. The current study's objective was to assess whether ageing and cumulative stress interact to accelerate cognitive decline. With 60 participants, Marshall et al. found that ageing and cumulative stress interact significantly to impair working memory performance in older adults, suggesting vulnerability to the cumulative effects of life events beyond 60 years old. To replicate and extend this finding, we increased the sample size by conducting 3 independent studies with 156 participants and improved the statistical methods by conducting an iterative Bayesian meta-analysis with Bayes factors. Bayes factors deliver a more comprehensive result because they provide evidence for either the null hypothesis (H0), the alternative hypothesis (H1) or for neither hypothesis due to evidence not being sufficiently sensitive. Young (18-35 yrs) and older (60-85 yrs) healthy adults were categorised as high or low stress based on their life events score derived from the Life Events Scale for Students or Social Readjustment Rating Scale, respectively. We measured accuracy and reaction time on a 2-back working memory task to provide: a) Bayes factors and b) Bayesian meta-analysis, which iteratively added each study's effect sizes to evaluate the overall strength of evidence that ageing, cumulative stress and/or the combination of the two detrimentally affect working memory performance. Using a larger sample (N = 156 vs. N = 60) and a more powerful statistical approach, we did not replicate the robust age by cumulative stress interaction effect found by Marshall et al.. The effects of ageing and cumulative stress also fell within the anecdotal range (⅓ Collapse

Key Words Collapse

MESH Headings

• Humans
• Aged
• Middle Aged
• Memory, Short-Term
• Bayes Theorem
• Quality of Life
• Cognition
• Aging

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Grants Collapse

Affiliation(s)

Denise Wallace Department of Psychology and Centre for Brain Science, University of Essex, Colchester, Essex, United Kingdom
Nicholas R. Cooper Department of Psychology and Centre for Brain Science, University of Essex, Colchester, Essex, United Kingdom
Alejandra Sel Department of Psychology and Centre for Brain Science, University of Essex, Colchester, Essex, United Kingdom
Riccardo Russo Department of Psychology and Centre for Brain Science, University of Essex, Colchester, Essex, United Kingdom Department of Behavioral and Brain Sciences, University of Pavia, Pavia, Italy

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Back to the future: Progressing memory research in eating disorders

OBJECTIVE

Human behaviors, thoughts, and emotions are guided by memories of the past. Thus, there can be little doubt that memory plays a fundamental role in the behaviors (e.g., binging), thoughts (e.g., body-image concerns), and emotions (e.g., guilt) that characterize eating disorders (EDs). Although a growing body of research has begun to investigate the role of memory in EDs, this literature is limited in numerous ways and has yet to be integrated into an overarching framework.

METHODS

In the present article, we provide an operational framework for characterizing different domains of memory, briefly review existing ED memory research within this framework, and highlight crucial gaps in the literature.

RESULTS

We distinguish between three domains of memory-episodic, procedural, and working-which differ based on functional attributes and underlying neural systems. Most recent ED memory research has focused on procedural memory broadly defined (e.g., reinforcement learning), and findings within all three memory domains are highly mixed. Further, few studies have attempted to assess these different domains simultaneously, though most behavior is achieved through coordination and competition between memory systems. We, therefore, offer recommendations for how to move ED research forward within each domain of memory and how to study the interactions between memory systems, using illustrative examples from other areas of basic and clinical research.

DISCUSSION

A stronger and more integrated understanding of the mechanisms that connect memory of past experiences to present ED behavior may yield more comprehensive theoretical models of EDs that guide novel treatment approaches.

PUBLIC SIGNIFICANCE

Memories of previous eating-related experiences may contribute to the onset and maintenance of eating disorders (EDs). However, research on the role of memory in EDs is limited, and distinct domains of ED memory research are rarely connected. We, therefore, offer a framework for organizing, progressing, and integrating ED memory research, to provide a better foundation for improving ED treatment and intervention going forward.

Glucocorticoid feedback paradox: a homage to Mary Dallman

As the end product of the hypothalamus-pituitary-adrenal (HPA) axis, the glucocorticoid hormones cortisol and corticosterone coordinate circadian activities, stress-coping, and adaptation to change. For this purpose, the hormone promotes energy metabolism and controls defense reactions in the body and brain. This life-sustaining action exerted by glucocorticoids occurs in concert with the autonomic nervous and immune systems, transmitters, growth factors/cytokines, and neuropeptides. The current contribution will focus on the glucocorticoid feedback paradox in the HPA-axis: the phenomenon that stress responsivity remains resilient if preceded by stress-induced secretion of glucocorticoid hormone, but not if this hormone is previously administered. Furthermore, in animal studies, the mixed progesterone/glucocorticoid antagonist RU486 or mifepristone switches to an apparent partial agonist upon repeated administration. To address these enigmas several interesting phenomena are highlighted. These include the conditional nature of the excitation/inhibition balance in feedback regulation, the role of glucose as a determinant of stress responsivity, and the potential of glucocorticoids in resetting the stress response system. The analysis of the feedback paradox provides also a golden opportunity to review the progress in understanding the role of glucocorticoid hormone in resilience and vulnerability during stress, the science that was burned deeply in Mary Dallman's emotions.

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.

A map of spatial navigation for neuroscience

Spatial navigation has received much attention from neuroscientists, leading to the identification of key brain areas and the discovery of numerous spatially selective cells. Despite this progress, our understanding of how the pieces fit together to drive behavior is generally lacking. We argue that this is partly caused by insufficient communication between behavioral and neuroscientific researchers. This has led the latter to under-appreciate the relevance and complexity of spatial behavior, and to focus too narrowly on characterizing neural representations of space-disconnected from the computations these representations are meant to enable. We therefore propose a taxonomy of navigation processes in mammals that can serve as a common framework for structuring and facilitating interdisciplinary research in the field. Using the taxonomy as a guide, we review behavioral and neural studies of spatial navigation. In doing so, we validate the taxonomy and showcase its usefulness in identifying potential issues with common experimental approaches, designing experiments that adequately target particular behaviors, correctly interpreting neural activity, and pointing to new avenues of research.

Preclinical Models of Chronic Stress: Adaptation or Pathology?

The experience of prolonged stress changes how individuals interact with their environment and process interoceptive cues, with the end goal of optimizing survival and well-being in the face of a now-hostile world. The chronic stress response includes numerous changes consistent with limiting further damage to the organism, including development of passive or active behavioral strategies and metabolic adjustments to alter energy mobilization. These changes are consistent with symptoms of pathology in humans, and as a result, chronic stress has been used as a translational model for diseases such as depression. While it is of heuristic value to understand symptoms of pathology, we argue that the chronic stress response represents a defense mechanism that is, at its core, adaptive in nature. Transition to pathology occurs only after the adaptive capacity of an organism is exhausted. We offer this perspective as a means of framing interpretations of chronic stress studies in animal models and how these data relate to adaptation as opposed to pathology.

The effects of hydrocortisone and yohimbine on human behavior in approach-avoidance conflicts

RATIONALE

Balancing approach of positive and avoidance of negative stimuli is essential when faced with approach-avoidance conflicts, e.g., situations with both positive and negative outcomes. This balance is disturbed in several mental disorders, e.g., excessive avoidance in anxiety disorders, and heightened approach in substance use disorders. Since stress is assumed to impact these disorders' etiology and maintenance, it seems crucial to understand how stress influences behavior in approach-avoidance conflicts. Indeed, some studies suggested altered approach-avoidance behavior under acute stress, but the mechanism underlying these effects is unknown.

OBJECTIVES

Investigate how the pharmacological manipulation of major stress mediators (cortisol and noradrenaline) influences task-based approach-avoidance conflict behavior in healthy individuals.

METHODS

Ninety-six participants (48 women, 48 men) received either 20mg hydrocortisone, 20mg yohimbine, both, or placebo before performing a task targeting foraging under predation in a fully crossed double-blind between-subject design. Moreover, we investigated effects of gender and endogenous testosterone and estradiol levels on approach-avoidance behavior.

RESULTS

While biological stress markers (cortisol concentration, alpha amylase activity) indicated successful pharmacological manipulation, behavior in approach-avoidance conflicts was not affected as expected. Although yohimbine administration affected risky foraging latency under predation, we found no main effect of hydrocortisone or their interaction on behavior. In contrast, we found gender differences for almost all behavioral outcome measures, which might be explained by differences in endogenous testosterone levels.

CONCLUSIONS

The investigated major stress mediators were not sufficient to imitate previously shown stress effects on approach-avoidance conflict behavior. We discuss potential reasons for our findings and implications for future research.

Chronic alcohol consumption shifts learning strategies and synaptic plasticity from hippocampus to striatum-dependent pathways

Introduction

The hippocampus and striatum have dissociable roles in memory and are necessary for spatial and procedural/cued learning, respectively. Emotionally charged, stressful events promote the use of striatal- over hippocampus-dependent learning through the activation of the amygdala. An emerging hypothesis suggests that chronic consumption of addictive drugs similarly disrupt spatial/declarative memory while facilitating striatum-dependent associative learning. This cognitive imbalance could contribute to maintain addictive behaviors and increase the risk of relapse.

Methods

We first examined, in C57BL/6 J male mice, whether chronic alcohol consumption (CAC) and alcohol withdrawal (AW) might modulate the respective use of spatial vs. single cue-based learning strategies, using a competition protocol in the Barnes maze task. We then performed in vivo electrophysiological studies in freely moving mice to assess learning-induced synaptic plasticity in both the basolateral amygdala (BLA) to dorsal hippocampus (dCA1) and BLA to dorsolateral striatum (DLS) pathways.

Results

We found that both CAC and early AW promote the use of cue-dependent learning strategies, and potentiate plasticity in the BLA → DLS pathway while reducing the use of spatial memory and depressing BLA → dCA1 neurotransmission.

Discussion

These results support the view that CAC disrupt normal hippocampo-striatal interactions, and suggest that targeting this cognitive imbalance through spatial/declarative task training could be of great help to maintain protracted abstinence in alcoholic patients.

Decision-Making and Risk-Propensity Changes during and after the COVID-19 Pandemic Lockdown

The imposition of lockdowns during the COVID-19 pandemic placed individuals under conditions of environmental stress, threatening individual and collective wellbeing. This study aimed to investigate the temporal effects of isolation and confinement during and after the Italian lockdown on decision-making, risk propensity, and cognitive control processes. The present study covered almost the entire Italian lockdown period (each week from the end of March to mid-May 2020), plus a follow-up measure (September 2020). At each time-point, respondents completed online behavioral tasks, which involved measuring risk-propensity (Balloon Analogue Risk Task), decision-making (Iowa Gambling Task), and cognitive flexibility (Category Switch Task). They also filled in questionnaires regarding subjective stress and anxiety. The main findings showed that the decision-making abilities of the respondents were affected as the confinement progressed. Furthermore, individuals who were more subjectively impacted by the lockdown/isolation experience exhibited impaired decision-making, especially during the lockdown. The results of the study highlight that prolonged confinement may affect human decision making, and help understand individuals' misbehaviors during emergencies and develop effective countermeasures aimed at reducing the burden of the healthcare system.

Competitive Neurocognitive Processes Following Bereavement

Bereavement is a common human experience that often involves significant impacts on psychological, emotional and even cognitive functioning. Though various psychological theories have been proposed to conceptualize the grief process, our current understanding of the underlying neurocognitive mechanisms of grief is limited. The present paper proposes a neurocognitive model to understand phenomena in typical grief, which links loss-related reactions to underlying learning and executive processes. We posit that the competitive relationship between the basal ganglia (BG) and circuitry involving the medial temporal lobe (MTL) underlies common cognitive experiences in grief such as a sense of "brain fog." Due to the intense stressor of bereavement, we suggest that these two systems' usually flexible interactive relationship become imbalanced. The resulting temporary dominance of either the BG or the MTL system is then manifested in perceived cognitive changes. Understanding the underlying neurocognitive mechanism in grief could inform ways to best support bereaved individuals.

Neuroendocrine response to a psychosocial stress test is not related to schizotypy but cortisol elevation predicts inflexibility of semantic memory retrieval

An altered stress response can contribute to the transition from preclinical psychotic symptoms to the clinical manifestation of schizophrenia and other psychotic disorders. The present study was aimed at testing the hypotheses that (i) the autonomic and neuroendocrine responses under psychosocial stress are dysregulated in individuals with high psychosis proneness (schizotypy); (ii) the magnitude of post-stress autonomic activation and cortisol release predicts alterations in semantic memory retrieval. The study was performed in 73 healthy individuals of both sexes with either high or low schizotypal traits preselected out of 609 individuals using the Schizotypal Personality Questionnaire. A psychosocial stress procedure based on public speech was used as a stress model. We found that individuals with high schizotypy engaged in less adaptive emotional stress-coping strategies than low schizotypy individuals. Yet, the neuroendocrine, immune, and sympathetic activation in response to the stress test was not different between the groups. Irrespective of the exposure to the stressor, individuals with high schizotypy were less fluent when retrieving associations from semantic memory. In addition, we demonstrated that acute psychosocial stress reduced the flexibility of semantic memory retrieval. The post-stress mental inflexibility was reliably predicted by the concomitant elevation of cortisol concentrations in saliva. The present study thus brings novel evidence indicating that the acute psychosocial challenge impairs retrieval flexibility in the semantic domain, which may be due to neuroendocrine activation.

Peer-elicited alcohol craving in adolescents and emerging adults: Bridging the laboratory and natural environment

BACKGROUND

Although peers figure prominently in developmental models of alcohol use, our understanding of the influence of peer social context in cue reactivity paradigms with adolescents and emerging adults in the human laboratory and the natural environment is limited. This study tested associations between alcohol craving among youth in the human laboratory using alcohol-related images, with and without peers, and in the natural environment using ecological momentary assessment (EMA).

METHODS

Data for this preregistered secondary analysis were collected prior to randomization in two medication trials (N = 115). Participants completed an image cue exposure paradigm at the baseline laboratory session followed by approximately 7 days of EMA.

RESULTS

In the laboratory, model-based mean comparisons from multilevel models (MLMs) showed that all drinking images elicited greater craving than neutral images. No differences were observed across the three image categories containing alcohol. Image category by age interactions demonstrated that, compared to older youth, younger youth displayed lower craving in response to neutral versus social drinking context with peers images and older, compared to younger, youth displayed higher craving in response to nonsocial drinking images versus social drinking contexts with peers images. In the natural environment, craving was greatest when youth were in the presence of alcohol-using peers and alcohol-related cues, regardless of age. Laboratory craving to alcohol images was positively associated with craving in the natural environment.

CONCLUSIONS

For youth, peers are a salient social context associated with increased craving, particularly in the natural environment. Laboratory cue reactivity to alcohol images predicted real-world craving, further supporting the ecological validity of this paradigm in youth.

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.

Does stress consistently favor habits over goal-directed behaviors? Data from two preregistered exact replication studies

Instrumental learning is controlled by two distinct parallel systems: goal-directed (action-outcome) and habitual (stimulus-response) processes. Seminal research by Schwabe and Wolf (2009, 2010) has demonstrated that stress renders behavior more habitual by decreasing goal-directed control. More recent studies yielded equivocal evidence for a stress-induced shift towards habitual responding, yet these studies used different paradigms to evaluate instrumental learning or used different stressors. Here, we performed exact replications of the original studies by exposing participants to an acute stressor either before (cf. Schwabe and Wolf, 2009) or directly after (cf. Schwabe and Wolf, 2010) an instrumental learning phase in which they had learned that distinct actions led to distinct, rewarding food outcomes (i.e., instrumental learning). Then, following an outcome devaluation phase in which one of the food outcomes was consumed until participants were satiated, action-outcome associations were tested in extinction. Despite successful instrumental learning and outcome devaluation and increased subjective and physiological stress levels following stress exposure, the stress and no-stress groups in both replication studies responded indifferently to valued and devalued outcomes. That is, non-stressed participants failed to demonstrate goal-directed behavioral control, thereby rendering the critical test of a shift from goal-directed to habitual control in the stress group inapt. Several reasons for these replication failures are discussed, including the rather indiscriminate devaluation of outcomes that may have contributed to indifferent responding during extinction, which emphasize the need to further our understanding of the boundary conditions in research aimed at demonstrating a stress-induced shift towards habitual control.

Adolescent social isolation shifts the balance of decision-making strategy from goal-directed action to habitual response in adulthood via suppressing the excitatory neurotransmission onto the direct pathway of the dorsomedial striatum

Adverse experience, such as social isolation, during adolescence is one of the major causes of neuropsychiatric disorders that extend from adolescence into adulthood, such as substance addiction, obsessive-compulsive disorder, and eating disorders leading to obesity. A common behavioral feature of these neuropsychiatric disorders is a shift in the balance of decision-making strategy from goal-directed action to habitual response. This study has verified that adolescent social isolation directly shifts the balance of decision-making strategy from goal-directed action to habitual response, and that it cannot be reversed by simple regrouping. This study has further revealed that adolescent social isolation induces a suppression in the excitatory neurotransmission onto the direct-pathway medium spiny neurons of the dorsomedial striatum (DMS), and that chemogenetically compensating this suppression effect shifts the balance of decision-making strategy from habitual response back to goal-directed action. These findings suggest that the plasticity in the DMS causes the shift in the balance of decision-making strategy, which would potentially help to develop a general therapy to treat the various neuropsychiatric disorders caused by adolescent social isolation. Such a study is especially necessary under the circumstances that social distancing and lockdown have caused during times of world-wide, society-wide pandemic.

Rapid effects of acute stress on cognitive emotion regulation

Acute stress has been shown to either enhance or impair emotion regulation (ER) performances. Besides sex, strategy use and stimulus intensity, another moderating factor appears to be timing of the ER task relative to stress exposure. Whereas somewhat delayed increases in the stress hormone cortisol have been shown to improve ER performances, rapid sympathetic nervous system (SNS) actions might oppose such effects via cognitive regulatory impairments. Here, we thus investigated rapid effects of acute stress on two ER strategies: reappraisal and distraction. N = 80 healthy participants (40 men & 40 women) were exposed to the Socially Evaluated Cold-Pressor Test or a control condition immediately prior to an ER paradigm which required them to deliberately downregulate emotional responses towards high intensity negative pictures. Subjective ratings and pupil dilation served as ER outcomes measures. Increases in salivary cortisol and cardiovascular activity (index of SNS activation) verified successful induction of acute stress. Unexpectedly, stress reduced subjective emotional arousal when distracting from negative pictures in men indicating regulatory improvements. However, this beneficial effect was particularly pronounced in the second half of the ER paradigm and fully mediated by already rising cortisol levels. In contrast, cardiovascular responses to stress were linked to decreased subjective regulatory performances of reappraisal and distraction in women. However, no detrimental effects of stress on ER occurred at the group level. Yet, our findings provide initial evidence for rapid, opposing effects of the two stress systems on the cognitive control of negative emotions that are critically moderated by sex.

Family firm ambidexterity: the influence of paradoxical tensions and the Entrepreneurial Family’s cohesion

This study presents paradoxical tensions as the ‘missing link’ at the intersection of the entrepreneurial family and family firm management: a link that crucially affects innovation-related decisions such as ambidexterity. Specifically, the study argues that the relationship between family cohesion and organizational ambidexterity within entrepreneurial family firms is mediated by paradoxical tensions (latent and salient). Drawing on survey data from 206 German family firms, support is found for the hypotheses advanced. Building on cognitive resource theory, this study demonstrates that differently perceived paradoxical tensions in entrepreneurial family firms have different meaningful effects on organizational ambidexterity. Implications for theory and future research are discussed.

A matter of habit? Stressful life events and cognitive flexibility in 15-month-olds

Exposure to chronic stress is associated with habitual learning in adults. We studied the origins of this association by examining the link between stressful life events and infant cognitive flexibility. The final sample consisted of N = 72 fifteen-month-old infants and their mothers. Mothers completed a survey on pre- and postnatal negative life events. To assess chronic stress physiologically, infant and maternal hair cortisol concentrations were determined for cortisol accumulation during the past 3 months. Each infant participated in two cognitive tasks in the laboratory. An instrumental learning task tested infants' ability to disengage from a habituated action when this action became ineffective (Seehagen et al., 2015). An age-adequate version of the A-not-B task tested infants' ability to find a toy at location B after repeatedly finding it at location A. Correlations between cortisol concentrations and postnatal negative life events (number, perceived impact) did not yield significance. Infant and maternal hair cortisol concentrations were not correlated. Infants' ability to shift to a new action in either task, controlled for acute stress, correlated neither with pre- and postnatal negative life events nor with cortisol concentrations. Taken together, these results indicate that the potential link between long-term stress exposure and cognitive flexibility might not be present in samples with low levels of psychosocial stress.

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.

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.

Stress affects the prediction of others' behavior

Predicting behavior of other people is vital for successful social interactions. We tested whether a stress-induced cortisol increase affects healthy young men's prediction of another individual's behavior. Forty-two participants were randomly assigned to a stress or to a control condition. Afterwards, they participated in a modified false-belief task that not only tests false-belief understanding but also the tendency to predict another person's future behavior based on his former behavior. Subjective ratings and salivary cortisol concentrations revealed a successful stress induction. Stress did not affect participants' attribution of false beliefs but it increased the probability to predict that a protagonist would act according to his former behavior. Recognizing that stress fosters the interpretation of others' behavior following their former behavior and not their current goals extends previous research showing that stress fosters our own habitual behavior.

Stress effects on memory retrieval of aversive and appetitive instrumental counterconditioning in men

Extinction training creates a second inhibitory memory trace and effectively reduces conditioned responding. However, acute stress inhibits the retrieval of this extinction memory trace. It is not known whether this also applies to other forms of associative learning such as instrumental counterconditioning, where previously learned associations are reversed and paired with the opposite valence. Therefore, the current preregistered study investigates whether stress decreases the retrieval of instrumental counterconditioning memories with aversive and appetitive consequences. Fifty-two healthy men were randomly assigned to either a stress or control group and took part in a two-day instrumental learning paradigm. During a first phase, participants learned that pressing specific buttons in response to the presentation of four neutral stimuli either leads to gaining or losing money. During a second phase, two stimuli reversed their contingencies (counterconditioning). One day later, participants were exposed to acute stress or a control condition prior to the same task, which no longer included feedback about gains or losses. Stressed participants showed more approach behavior towards appetitive and less avoidance behavior towards aversive stimuli as compared to non-stressed participants. Our findings indicate that stress effects on memory retrieval differ depending on the associative learning approach in men. These differences might be related to stress effects on decision making and different motivational systems involved.

Evaluation of changes in the cognitive function of adult cynomolgus monkeys under stress induced by audio-visual stimulation by applying modified finger maze test

Stress in life is ubiquitous and unavoidable. Prolonged exposure to severe stress can lead to physical intolerance and impair cognitive function. Non-human primates are considered to be the best animal model for studying cognitive function, especially memory and attention. The finger maze test, with the advantages of short training time and lower cost, is recommended to evaluate learning and memory in non-human primates. In this study, we modified the finger maze test method to evaluate the cognitive function of single-housed cynomolgus monkeys. The flexibility and attention of cynomolgus monkeys were assessed by performing the complex task test and the stranger intrusion interference test, respectively, which increased the difficulty of obtaining rewards, and the ability of long-term memory was also evaluated by the memory test. Furthermore, the changes in cognitive function of the cynomolgus monkeys were tested by using the finger maze test after audio-visual stimulation, and the changes in the cortisol levels during stimulation were also analyzed. We found that, after completing the learning test, there was no significant decrease in their success rate when monkeys processed multitasks at the same time. In the stranger intrusion interference test, all subjects were distracted, but the accuracy did not decrease. The monkeys completed the memory tests in the 1st and 2nd months after the learning tests, with a high success rate. However, the success rate decreased significantly at the end of the 4th month. During audio-visual stimulation, the plasma cortisol level significantly increased in the first 2 months and was maintained at a high level thereafter. One month after audio-visual stimulation, the accuracy of the memory test was significantly reduced, and the total time of distraction was significantly prolonged. In conclusion, chronic audio-visual stimulation can increase blood cortisol levels and impair cognitive function. The modified finger maze test can evaluate many aspects of cognitive function and assess the changes in the cognitive function of adult cynomolgus monkeys under stress.

Cardiovascular reactivity during sadness induction predicts inhibitory control performance

Higher negative affectivity has an association with decreased executive function and cognitive control. Heart rate variability (HRV) serves as an index of cardiac vagal regulation differences in the autonomic nervous system for both cognition and emotion. The current study investigates this association using a classic as well as emotional antisaccade paradigm to study inhibitory control performance. Ninety participants completed affective questionnaires (Beck Depression Inventory-II, and Mood Scale), a 6-minute baseline electrocardiogram, and two different antisaccade tasks. After the baseline, subjects were presented with a video sequence with either neutral, sad, or emotionally arousing content. By subtracting the baseline from the video sequence, we computed HRV reactivity and tested whether the reactivity score could predict inhibitory control performance. We hypothesized that this would be the case in both the sadness and arousal group, but not in the neutral one. Furthermore, we awaited significant performance differences between experimental groups. Contrary to our assumption, inhibitory control performance did not differ between experimental groups. Moreover, there was no significant relation between affective measures and task performance. Nevertheless, cardiovascular reactivity in terms of HRV was predictive of error rates in both antisaccade tasks in the sadness group. We could find this effect neither in the neutral nor in the arousal group. In addition, BDI scores moderated the effect in the emotional task. Results indicate that emotional reactivity to a sad video stimulus as indexed by HRV as well as the interaction with current emotional state predict inhibitory control performance.

A psychophysiological investigation of mourning: There are two sides to the story

Mourning constitutes an important human emotion, which might cause—among other things—major depressive symptoms when lasting for too long. To date, no study investigated whether mourning is related to specific psychophysiological activation patterns. Therefore, we examined physiological reactions induced by iconographic mourning-related stimuli in comparison to neutral and attachment stimuli in healthy adults (N = 77, mean age: 21.9). We evaluated pupillometric and eye-tracking parameters as well as heart rate variability (HRV) and skin conductance (EDA). Eye-tracking revealed a stronger dilated pupil during mourning in comparison to the neutral, but not to the attachment condition; furthermore, fixation patterns revealed less fixations on mourning stimuli. While HF HRV was reduced during mourning and attachment, we found no differences concerning EDA parameters between conditions. Results suggest specific eye-movement and pupil adaptations during representations of mourning, which might point toward inward cognition or avoidance, but no specific physiological pattern concerning HRV and EDA.

Acute stress influences strategy preference when dealing with high intensity emotions in men

Stress has been shown to initiate a shift from flexible to rigid, less demanding cognitive processes. Reappraisal and distraction are two emotion regulation strategies varying in their cognitive demands. Previous studies indicate that stress improves regulatory performances of high arousal stimuli. We thus investigated whether acute stress alters the preference for reappraisal or distraction when downregulating emotions of different intensities and further explored its influence on regulatory outcomes. Eighty males were either socially stressed (n=40) or exposed to a control condition (n=40) prior to an emotion regulation choice paradigm. Stress increased the probability to prefer distraction for downregulating high intensity emotions. Stressed (vs. control) participants reported to be generally more successful in regulating high intensity emotions, which was positively associated with cortisol but not alpha-amylase increases. Our findings provide initial evidence that stress fosters a preference for less demanding regulatory options, suggesting favorable strategy choices in response to acute stressors. DATA AVAILABILITY: The data that support the findings of this study are available at the Open Science Framework (OSF) under https://osf.io/b9ae3/.

Adult hippocampal neurogenesis shapes adaptation and improves stress response: a mechanistic and integrative perspective

Adult hippocampal neurogenesis (AHN) represents a remarkable form of neuroplasticity that has increasingly been linked to the stress response in recent years. However, the hippocampus does not itself support the expression of the different dimensions of the stress response. Moreover, the main hippocampal functions are essentially preserved under AHN depletion and adult-born immature neurons (abGNs) have no extrahippocampal projections, which questions the mechanisms by which abGNs influence functions supported by brain areas far from the hippocampus. Within this framework, we propose that through its computational influences AHN is pivotal in shaping adaption to environmental demands, underlying its role in stress response. The hippocampus with its high input convergence and output divergence represents a computational hub, ideally positioned in the brain (1) to detect cues and contexts linked to past, current and predicted stressful experiences, and (2) to supervise the expression of the stress response at the cognitive, affective, behavioral, and physiological levels. AHN appears to bias hippocampal computations toward enhanced conjunctive encoding and pattern separation, promoting contextual discrimination and cognitive flexibility, reducing proactive interference and generalization of stressful experiences to safe contexts. These effects result in gating downstream brain areas with more accurate and contextualized information, enabling the different dimensions of the stress response to be more appropriately set with specific contexts. Here, we first provide an integrative perspective of the functional involvement of AHN in the hippocampus and a phenomenological overview of the stress response. We then examine the mechanistic underpinning of the role of AHN in the stress response and describe its potential implications in the different dimensions accompanying this response.

Pyk2 Stabilizes Striatal Medium Spiny Neuron Structure and Striatal-Dependent Action

In day-to-day life, we often choose between pursuing familiar behaviors that have been rewarded in the past or adjusting behaviors when new strategies might be more fruitful. The dorsomedial striatum (DMS) is indispensable for flexibly arbitrating between old and new behavioral strategies. The way in which DMS neurons host stable connections necessary for sustained flexibility is still being defined. An entry point to addressing this question may be the structural scaffolds on DMS neurons that house synaptic connections. We find that the non-receptor tyrosine kinase Proline-rich tyrosine kinase 2 (Pyk2) stabilizes both dendrites and spines on striatal medium spiny neurons, such that Pyk2 loss causes dendrite arbor and spine loss. Viral-mediated Pyk2 silencing in the DMS obstructs the ability of mice to arbitrate between rewarded and non-rewarded behaviors. Meanwhile, the overexpression of Pyk2 or the closely related focal adhesion kinase (FAK) enhances this ability. Finally, experiments using combinatorial viral vector strategies suggest that flexible, Pyk2-dependent action involves inputs from the medial prefrontal cortex (mPFC), but not the ventrolateral orbitofrontal cortex (OFC). Thus, Pyk2 stabilizes the striatal medium spiny neuron structure, likely providing substrates for inputs, and supports the capacity of mice to arbitrate between novel and familiar behaviors, including via interactions with the medial-prefrontal cortex.

Dopaminergic and noradrenergic modulation of stress-induced alterations in brain activation associated with goal-directed behaviour

BACKGROUND

Acute stress is thought to reduce goal-directed behaviour, an effect purportedly associated with stress-induced release of catecholamines. In contrast, experimentally increased systemic catecholamine levels have been shown to increase goal-directed behaviour. Whether experimentally increased catecholamine function can modulate stress-induced reductions in goal-directed behaviour and its neural substrates, is currently unknown.

AIM

To assess whether and how experimentally induced increases in dopamine and noradrenaline contribute to the acute stress effects on goal-directed behaviour and associated brain activation.

METHODS

One hundred participants underwent a stress induction protocol (Maastricht acute stress test; MAST) or a control procedure and received methylphenidate (MPH) (40 mg, oral) or placebo according to a 2 × 2 between-subjects design. In a well-established instrumental learning paradigm, participants learnt stimulus-response-outcome associations, after which rewards were selectively devalued. Participants' brain activation and associated goal-directed behaviour were assessed in a magnetic resonance imaging scanner at peak cortisol/MPH concentrations.

RESULTS

The MAST and MPH increased physiological measures of stress (salivary cortisol and blood pressure), but only MAST increased subjective measures of stress. MPH modulated stress effects on activation of brain areas associated with goal-directed behaviour, including insula, putamen, amygdala, medial prefrontal cortex, frontal pole and orbitofrontal cortex. However, MPH did not modulate the tendency of stress to induce a reduction in goal-directed behaviour.

CONCLUSION

Our neuroimaging data suggest that MPH-induced increases in dopamine and noradrenaline reverse stress-induced changes in key brain regions associated with goal-directed behaviour, while behavioural effects were absent. These effects may be relevant for preventing stress-induced maladaptive behaviour like in addiction or binge eating disorder.

It is Not (Always) the Mismatch That Beats You-On the Relationship Between Interaction of Early and Recent Life Stress and Emotion Regulation, an fMRI Study

Stress may impact the ability to effectively regulate emotions. To study the impact of stressful experiences in early and recent life on emotion regulation, we examined the relationship between early life stress, recent stress, and brain activation during cognitive reappraisal. We investigated two regulation goals: the decrease and increase of emotional response to both negative and positive stimuli. Furthermore, two models of stress consequences were examined: the cumulative and match/mismatch models. A total of 83 participants (M_age = 21.66) took part in the study. There was an interaction between cumulative stress and stimuli valence in the cuneus, superior lateral occipital cortex, superior parietal lobule, supramarginal gyrus extending to superior temporal gyrus, and precentral gyrus extending to supplementary motor area. Interaction between mismatched stress index and stimuli valence was found in the left hippocampus, left insula extending to the orbitofrontal cortex and amygdala, and in a cluster including the anterior cingulate cortex, superior frontal gyrus, and frontal pole. Furthermore, there were differences between the effects of cumulative and mismatched stress indices on brain activation during reappraisal of positive but not negative stimuli. Results indicate that cumulative stress and match/mismatch approaches are both useful for explaining brain activation during reappraisal. This finding is important for our understanding of the multifaceted impact of stress on emotion regulation.

Don't stress, it's under control: Neural correlates of stressor controllability in humans

Animal research has repeatedly shown that control is a key variable in the brain's stress response. Uncontrollable stress triggers a release of monoamines, impairing prefrontal functions while enhancing subcortical circuits. Conversely, control over an adverse event involves prefrontally mediated downregulation of monoamine nuclei and is considered protective. However, it remains unclear to what extent these findings translate to humans. During functional magnetic resonance imaging, we subjected participants to controllable and uncontrollable aversive but non-painful electric stimuli, as well as to a control condition without aversive stimulation. In each trial, a symbol signalled whether participants could terminate the stressor through correct performance in a button-matching task or whether the stressor would be randomly terminated, i.e., uncontrollable. Along with neural responses, we assessed participants' accuracy, reaction times, and heart rate. To relate neural activations and subjective experience, we asked participants to rate perceived control, helplessness, and stress. Results were largely in line with our hypotheses. The vmPFC was generally deactivated by aversive stimulation, but this effect was attenuated when participants could terminate the stressor compared to when their responses had no effect. Furthermore, activation in stress-responsive regions, including the bilateral insula, was reduced during controllable trials. Under uncontrollable aversive stimulation, greater vmPFC recruitment was linked to reduced feelings of helplessness. An investigation of condition-dependant differences in vmPFC connectivity yielded no significant results. Our findings further corroborate animal research and emphasise the role of the vmPFC in controllability-dependant regulation of stress responses. Based on the results, we discuss future directions in the context of resilience research and mental health promotion.

Time-dependent changes in hippocampal and striatal glycogen long after maze training in male rats

Long-lasting biological changes reflecting past experience have been studied in and typically attributed to neurons in the brain. Astrocytes, which are also present in large number in the brain, have recently been found to contribute critically to learning and memory processing. In the brain, glycogen is primarily found in astrocytes and is metabolized to lactate, which can be released from astrocytes. Here we report that astrocytes themselves have intrinsic neurochemical plasticity that alters the availability and provision of metabolic substrates long after an experience. Rats were trained to find food on one of two versions of a 4-arm maze: a hippocampus-sensitive place task and a striatum-sensitive response task. Remarkably, hippocampal glycogen content increased while striatal levels decreased during the 30 days after rats were trained to find food in the place version, but not the response version, of the maze tasks. A long-term consequence of the durable changes in glycogen stores was seen in task-by-site differences in extracellular lactate responses activated by testing on a working memory task administered 30 days after initial training, the time when differences in glycogen content were most robust. These results suggest that astrocytic plasticity initiated by a single experience may augment future availability of energy reserves, perhaps priming brain areas to process learning of subsequent experiences more effectively.

Males with low risk-taking propensity overestimate risk under acute psychological stress

Arousing research has investigated stressed individuals' decision biases, but whether and how stress and individual traits interact to impact the underlying decision-making process is unknown. Here, we aim to explore the effect of acute stress on the interaction between the objective level of risk and subjective risk preference (i.e. risk-taking propensity). Eighty-three healthy males participated in the study. We adopted the Trier Social Stress Test (TSST) to induce acute psychological stress and categorized participants into the high or low risk-taking propensity (HRP/LRP) group according to their traits in daily life. The Balloon Analogue Risk Task (BART) was applied to measure their feedback processing in a risky decision task, while behavioral indexes and EEG signals were recorded. The results showed that stressful participants pumped fewer times than the controls, especially for the LRP under stress, indicating that they were more willing to avoid taking risks. Compared with the stressed HRP group, the stressed LRP showed higher salivary cortisol responses and a more positive FRN following positive feedback in higher risk levels. It implies that acute psychological stress leads the LRP to overestimate the risk probability and become more cautious in the sequential processing of risk. These findings highlight the role of the feedback process and individual traits in risky decision-making under stress.

The influence of stress on distractor-response bindings

Stimuli and responses that occur in close temporal contiguity are bound to each other and stored in short-term episodic traces or event files. A repetition of any of the features within an event file results in the retrieval of the entire event file and can influence responding. Along with task-relevant features, event files also contain task-irrelevant features, which are also bound to responses - distractor-response binding. In the present study, the distractor-response binding effect was examined under stress. Stress was induced via a Cold Pressor Test (CPT) and was manipulated between subjects. Distractor-response binding effects were measures at pre- and post-intervention. The CPT produced reliable effects on cortisol measurements and subjective ratings, however, no difference in the distractor-response binding effects between the groups was observed. Results are discussed against the background of the inconsistent results in the literature with respect to stimulus-response binding and stress.

Exposure to acute stress affects the retrieval of out-group related bias in healthy men

Individuals have a tendency to show enhanced vigilance to groups of which they themselves are not a member. Stress can up-regulate hypervigilance towards threatening stimuli and was shown to promote the reinstatement of out-group related biases in a previous study conducted in women only. The current study examines how exposure to acute stress affects the retrieval of out-group related extinction biases in male participants. Results showed that men exerted a specific out-group related bias at the beginning of extinction training indexed by higher skin conductance responses (SCRs) towards out-group faces, while stress led to a return of this extinguished out-group bias. Specifically, the stress group showed higher SCRs towards out-group faces during retrieval compared to the control group and the bias index was negatively related to post-stress cardiovascular recovery. These results indicate the important interaction between stress and intergroup bias in fear conditioning, along with a potential modulation of sex.

Can Habits Impede Creativity by Inducing Fixation?

In a competitive and ever-changing world, the ability to generate outstanding ideas is crucial. However, this process can be impeded by factors such as fixation on ideas that emerged through prior experience. The aim of the present study was to shed light on the fixating effect of habits on creativity. To this end, healthy young adults were asked to generate alternative uses for items that differed in their frequency of use in the Alternative Uses Task (a standardized test for divergent thinking). We predicted that frequent past use of an item would lead to the formation of stimulus-response associations between the item and its most frequent use(s) and thereby hinder idea generation. Indeed, individuals were less flexible (but more fluent) in generating ideas for frequently used items than for unknown items. Additionally, we found that subjective automaticity of idea generation was negatively related with flexibility. Finally, we investigated whether individual differences in general habit tendency influence creativity, by relating performance on the Slips-of-Action task (an outcome devaluation paradigm extensively used in habit research) to performance on the Alternative Uses Task, the Candle Problem (a classic convergent thinking task) and two puzzles (non-conventional problem-solving tasks). While we did not find a significant relationship between habit tendency and the Alternative Uses Task or the Candle Problem scores, the tendency to rely on habits predicted probability to succeed and latency to solve one of the puzzles: less habit-prone participants were more likely to solve it and to do so faster. In conclusion, our study provides evidence for the notion that habits can negatively impact creativity and opens promising future avenues of research in this field.

Mathematics Disability vs. Learning Disability: A 360 Degree Analysis

A fundamental issue for research in mathematics disability (MD) and reading disability (RD) is: If these disabilities are clearly distinct, why is there so high a level of comorbidity, together with the converse; if these disabilities are so similar, why are there clear differences in underlying causes and aetiology? In order to address this puzzle, we introduce the “360 degree analysis” (360DA) framework and apply it to the overlap between RD and MD. The 360DA process starts by analyzing the issue from four perspectives: theoretical, developmental, affective, and pedagogical. Under 360DA, these analyses are then integrated to provide insights for theory, and for individual assessment and support, together with directions for future progress. The analyses confirm extensive similarities between arithmetic and reading development in terms of rote learning, executive function (EF), and affective trauma, but also major differences in terms of the conceptual needs, the motor coordination needs, and the methods of scaffolding. In terms of theory, commonalities are interpreted naturally in terms of initial general developmental delay followed by domain-independent affective trauma following school failure. Dissociations are interpreted in terms of cerebellar vs. hippocampal learning networks, sequential vs. spatial processing, and language vs. spatial scaffolding, with a further dimension of the need for accurate fixation for reading. The framework has significant theoretical and applied implications.

Applying the Science of Habit Formation to Evidence-Based Psychological Treatments for Mental Illness

Habits affect nearly every aspect of our physical and mental health. Although the science of habit formation has long been of interest to psychological scientists across disciplines, we propose that applications to clinical psychological science have been insufficiently explored. In particular, evidence-based psychological treatments (EBPTs) are interventions targeting psychological processes that cause and/or maintain mental illness and that have been developed and evaluated scientifically. An implicit goal of EBPTs is to disrupt unwanted habits and develop desired habits. However, there has been insufficient attention given to habit-formation principles, theories, and measures in the development and delivery of EBTPs. Herein we consider whether outcomes following an EBPT would greatly improve if the basic science of habit formation were more fully leveraged. We distill six ingredients that are central to habit formation and demonstrate how these ingredients are relevant to EBPTs. We highlight practice points and an agenda for future research. We propose that there is an urgent need for research to guide the application of the science of habit formation and disruption to the complex "real-life" habits that are the essence of EBPTs.

Acute Psychosocial Stress Increases Cognitive-Effort Avoidance

Adverse effects following acute stress are traditionally thought to reflect functional impairments of central executive-dependent cognitive-control processes. However, recent evidence demonstrates that cognitive-control application is perceived as effortful and aversive, indicating that stress-related decrements in cognitive performance could denote decreased motivation to expend effort instead. To investigate this hypothesis, we tested 40 young, healthy individuals (20 female, 20 male) under both stress and control conditions in a 2-day study that had a within-subjects design. Cognitive-effort avoidance was assessed using the demand-selection task, in which participants chose between performing low-demand and high-demand variants of a task-switching paradigm. We found that acute stress indeed increased participants' preference for less demanding behavior, whereas task-switching performance remained intact. Additional Bayesian and multiverse analyses confirmed the robustness of this effect. Our findings provide novel insights into how stressful experiences shape behavior by modulating our motivation to employ cognitive control.

Interaction between decision-making and interoceptive representations of bodily arousal in frontal cortex

How bodily arousal states influence decision-making has been a central question in psychology, but the neural mechanisms are unclear. We recorded heart rate (HR), a measure of bodily arousal, while simultaneously monitoring neural activity in orbitofrontal cortex (OFC) and dorsal anterior cingulate cortex (dACC) of macaques making reward-guided decisions. In intact macaques, higher HR was associated with shorter reaction times. Concurrently, the activity of a set of neurons in OFC and dACC selectively encoded HR. Following amygdala lesions, HR generally increased, and now the relationship between HR and reaction times was altered. At the neural level, the balance of encoding in dACC shifted toward signaling HR, suggesting a specific mechanism through which bodily arousal influences decision-making.

Decision-making and representations of arousal are intimately linked. Behavioral investigations have classically shown that either too little or too much bodily arousal is detrimental to decision-making, indicating that there is an inverted “U” relationship between bodily arousal and performance. How these processes interact at the level of single neurons as well as the neural circuits involved are unclear. Here we recorded neural activity from orbitofrontal cortex (OFC) and dorsal anterior cingulate cortex (dACC) of macaque monkeys while they made reward-guided decisions. Heart rate (HR) was also recorded and used as a proxy for bodily arousal. Recordings were made both before and after subjects received excitotoxic lesions of the bilateral amygdala. In intact monkeys, higher HR facilitated reaction times (RTs). Concurrently, a set of neurons in OFC and dACC selectively encoded trial-by-trial variations in HR independent of reward value. After amygdala lesions, HR increased, and the relationship between HR and RTs was altered. Concurrent with this change, there was an increase in the proportion of dACC neurons encoding HR. Applying a population-coding analysis, we show that after bilateral amygdala lesions, the balance of encoding in dACC is skewed away from signaling either reward value or choice direction toward HR coding around the time that choices are made. Taken together, the present results provide insight into how bodily arousal and decision-making are signaled in frontal cortex.

Different underlying mechanisms for high and low arousal in probabilistic learning in humans

Humans are uniquely capable of adapting to highly changing environments by updating relevant information and adjusting ongoing behaviour accordingly. Here we show how this ability -termed cognitive flexibility- is differentially modulated by high and low arousal fluctuations. We implemented a probabilistic reversal learning paradigm in healthy participants as they transitioned towards sleep or physical extenuation. The results revealed, in line with our pre-registered hypotheses, that low arousal leads to diminished behavioural performance through increased decision volatility, while performance decline under high arousal was attributed to increased perseverative behaviour. These findings provide evidence for distinct patterns of maladaptive decision-making on each side of the arousal inverted u-shaped curve, differentially affecting participants' ability to generate stable evidence-based strategies, and introduces wake-sleep and physical exercise transitions as complementary experimental models for investigating neural and cognitive dynamics.