Imager-A mobile health mental imagery-based ecological momentary intervention targeting reward sensitivity: A randomized controlled trial

Robust reward sensitivity may help preserve mental well-being in the face of adversity and has been proposed as a key stress resilience factor. Here, we present a mobile health application, "Imager," which targets reward sensitivity by training individuals to create mental images of future rewarding experiences. We conducted a two-arm randomized controlled trial with 95 participants screened for reward sensitivity. Participants in the intervention group received an ecological momentary intervention-Imager, which encouraged participants to create mental images of rewarding events for 1 week. The control group participants received only ecological momentary assessment, without the instruction to generate mental images. Adherence to Imager was high; participants in the intervention group engaged in 88% of the planned activities. In the follow-up assessment, the intervention group reported less mental health symptoms, mainly in depression (β = -0.34, df = 93, p = .004) and less perceived stress (β = -0.18, df = 93, p = .035), than control group participants and compared with the baseline assessment. Our results show the positive effects of Imager on mental health symptoms. The encouraging effects of the app on mental health outcomes may lead to greater use of ecological momentary interventions in the clinical preventive practice of affective disorders.

Detecting Prolonged Stress in Real Life Using Wearable Biosensors and Ecological Momentary Assessments: Naturalistic Experimental Study

BACKGROUND

Increasing efforts toward the prevention of stress-related mental disorders have created a need for unobtrusive real-life monitoring of stress-related symptoms. Wearable devices have emerged as a possible solution to aid in this process, but their use in real-life stress detection has not been systematically investigated.

OBJECTIVE

We aimed to determine the utility of ecological momentary assessments (EMA) and physiological arousal measured through wearable devices in detecting ecologically relevant stress states.

METHODS

Using EMA combined with wearable biosensors for ecological physiological assessments (EPA), we investigated the impact of an ecological stressor (ie, a high-stakes examination week) on physiological arousal and affect compared to a control week without examinations in first-year medical and biomedical science students (51/83, 61.4% female). We first used generalized linear mixed-effects models with maximal fitting approaches to investigate the impact of examination periods on subjective stress exposure, mood, and physiological arousal. We then used machine learning models to investigate whether we could use EMA, wearable biosensors, or the combination of both to classify momentary data (ie, beeps) as belonging to examination or control weeks. We tested both individualized models using a leave-one-beep-out approach and group-based models using a leave-one-subject-out approach.

RESULTS

During stressful high-stakes examination (versus control) weeks, participants reported increased negative affect and decreased positive affect. Intriguingly, physiological arousal decreased on average during the examination week. Time-resolved analyses revealed peaks in physiological arousal associated with both momentary self-reported stress exposure and self-reported positive affect. Mediation models revealed that the decreased physiological arousal in the examination week was mediated by lower positive affect during the same period. We then used machine learning to show that while individualized EMA outperformed EPA in its ability to classify beeps as originating from examinations or from control weeks (1603/4793, 33.45% and 1648/4565, 36.11% error rates, respectively), a combination of EMA and EPA yields optimal classification (1363/4565, 29.87% error rate). Finally, when comparing individualized models to group-based models, we found that the individualized models significantly outperformed the group-based models across all 3 inputs (EMA, EPA, and the combination).

CONCLUSIONS

This study underscores the potential of wearable biosensors for stress-related mental health monitoring. However, it emphasizes the necessity of psychological context in interpreting physiological arousal captured by these devices, as arousal can be related to both positive and negative contexts. Moreover, our findings support a personalized approach in which momentary stress is optimally detected when referenced against an individual's own data.

Psychological Resilience Factors and Their Association With Weekly Stressor Reactivity During the COVID-19 Outbreak in Europe: Prospective Longitudinal Study

BACKGROUND

Cross-sectional relationships between psychosocial resilience factors (RFs) and resilience, operationalized as the outcome of low mental health reactivity to stressor exposure (low "stressor reactivity" [SR]), were reported during the first wave of the COVID-19 pandemic in 2020.

OBJECTIVE

Extending these findings, we here examined prospective relationships and weekly dynamics between the same RFs and SR in a longitudinal sample during the aftermath of the first wave in several European countries.

METHODS

Over 5 weeks of app-based assessments, participants reported weekly stressor exposure, mental health problems, RFs, and demographic data in 1 of 6 different languages. As (partly) preregistered, hypotheses were tested cross-sectionally at baseline (N=558), and longitudinally (n=200), using mixed effects models and mediation analyses.

RESULTS

RFs at baseline, including positive appraisal style (PAS), optimism (OPT), general self-efficacy (GSE), perceived good stress recovery (REC), and perceived social support (PSS), were negatively associated with SR scores, not only cross-sectionally (baseline SR scores; all P<.001) but also prospectively (average SR scores across subsequent weeks; positive appraisal (PA), P=.008; OPT, P<.001; GSE, P=.01; REC, P<.001; and PSS, P=.002). In both associations, PAS mediated the effects of PSS on SR (cross-sectionally: 95% CI -0.064 to -0.013; prospectively: 95% CI -0.074 to -0.0008). In the analyses of weekly RF-SR dynamics, the RFs PA of stressors generally and specifically related to the COVID-19 pandemic, and GSE were negatively associated with SR in a contemporaneous fashion (PA, P<.001; PAC,P=.03; and GSE, P<.001), but not in a lagged fashion (PA, P=.36; PAC, P=.52; and GSE, P=.06).

CONCLUSIONS

We identified psychological RFs that prospectively predict resilience and cofluctuate with weekly SR within individuals. These prospective results endorse that the previously reported RF-SR associations do not exclusively reflect mood congruency or other temporal bias effects. We further confirm the important role of PA in resilience.

Investigating two mobile just-in-time adaptive interventions to foster psychological resilience: research protocol of the DynaM-INT study

BACKGROUND

Stress-related disorders such as anxiety and depression are highly prevalent and cause a tremendous burden for affected individuals and society. In order to improve prevention strategies, knowledge regarding resilience mechanisms and ways to boost them is highly needed. In the Dynamic Modelling of Resilience - interventional multicenter study (DynaM-INT), we will conduct a large-scale feasibility and preliminary efficacy test for two mobile- and wearable-based just-in-time adaptive interventions (JITAIs), designed to target putative resilience mechanisms. Deep participant phenotyping at baseline serves to identify individual predictors for intervention success in terms of target engagement and stress resilience.

METHODS

DynaM-INT aims to recruit N = 250 healthy but vulnerable young adults in the transition phase between adolescence and adulthood (18-27 years) across five research sites (Berlin, Mainz, Nijmegen, Tel Aviv, and Warsaw). Participants are included if they report at least three negative burdensome past life events and show increased levels of internalizing symptoms while not being affected by any major mental disorder. Participants are characterized in a multimodal baseline phase, which includes neuropsychological tests, neuroimaging, bio-samples, sociodemographic and psychological questionnaires, a video-recorded interview, as well as ecological momentary assessments (EMA) and ecological physiological assessments (EPA). Subsequently, participants are randomly assigned to one of two ecological momentary interventions (EMIs), targeting either positive cognitive reappraisal or reward sensitivity. During the following intervention phase, participants' stress responses are tracked using EMA and EPA, and JITAIs are triggered if an individually calibrated stress threshold is crossed. In a three-month-long follow-up phase, parts of the baseline characterization phase are repeated. Throughout the entire study, stressor exposure and mental health are regularly monitored to calculate stressor reactivity as a proxy for outcome resilience. The online monitoring questionnaires and the repetition of the baseline questionnaires also serve to assess target engagement.

DISCUSSION

The DynaM-INT study intends to advance the field of resilience research by feasibility-testing two new mechanistically targeted JITAIs that aim at increasing individual stress resilience and identifying predictors for successful intervention response. Determining these predictors is an important step toward future randomized controlled trials to establish the efficacy of these interventions.

Study protocol for a randomised controlled trial investigating the effects of Mindfulness Based Stress Reduction on stress regulation and associated neurocognitive mechanisms in stressed university students: the MindRest study

BACKGROUND

Stress-related disorders are a growing public health concern. While stress is a natural and adaptive process, chronic exposure to stressors can lead to dysregulation and take a cumulative toll on physical and mental well-being. One approach to coping with stress and building resilience is through Mindfulness-Based Stress Reduction (MBSR). By understanding the neural mechanisms of MBSR, we can gain insight into how it reduces stress and what drives individual differences in treatment outcomes. This study aims to establish the clinical effects of MBSR on stress regulation in a population that is susceptible to develop stress-related disorders (i.e., university students with mild to high self-reported stress), to assess the role of large-scale brain networks in stress regulation changes induced by MBSR, and to identify who may benefit most from MBSR.

METHODS

This study is a longitudinal two-arm randomised, wait-list controlled trial to investigate the effects of MBSR on a preselected, Dutch university student population with elevated stress levels. Clinical symptoms are measured at baseline, post-treatment, and three months after training. Our primary clinical symptom is perceived stress, with additional measures of depressive and anxiety symptoms, alcohol use, stress resilience, positive mental health, and stress reactivity in daily life. We investigate the effects of MBSR on stress regulation in terms of behaviour, self-report measures, physiology, and brain activity. Repetitive negative thinking, cognitive reactivity, emotional allowance, mindfulness skills, and self-compassion will be tested as potential mediating factors for the clinical effects of MBSR. Childhood trauma, personality traits and baseline brain activity patterns will be tested as potential moderators of the clinical outcomes.

DISCUSSION

This study aims to provide valuable insights into the effectiveness of MBSR in reducing stress-related symptoms in a susceptible student population and crucially, to investigate its effects on stress regulation, and to identify who may benefit most from the intervention.

TRIAL REGISTRATION

Registered on September 15, 2022, at clinicaltrials.gov, NCT05541263 .

Community engagement in epigenomic and neurocognitive research on post-traumatic stress disorder in Rwandans exposed to the 1994 genocide against the Tutsi: lessons learned

Epigenomic and neurocognitive studies have provided new perspectives on post-traumatic stress disorder and its intergenerational transmission. This article outlines the lessons learned from community engagement (CE) in such research on Rwandan genocide survivors. A strong trauma-related response was observed within the research project-targeted community (genocide survivors) during explanation of the project. CE also revealed privacy concerns, as community members worried that any leakage of genetic/(epi)genomic data could affect not only themselves but also their close relatives. Adopting a culture of CE in the process of research implementation enables the prioritization of targeted community needs and interests. Furthermore, CE has stimulated the development of mental healthcare interventions, which married couples can apply to protect their offspring and thus truly break the cycle of inherited vulnerability.

The STRESS-NL database: A resource for human acute stress studies across the Netherlands

Stress initiates a cascade of (neuro)biological, physiological, and behavioral changes, allowing us to respond to a challenging environment. The human response to acute stress can be studied in detail in controlled settings, usually in a laboratory environment. To this end, many studies employ acute stress paradigms to probe stress-related outcomes in healthy and patient populations. Though valuable, these studies in themselves often have relatively limited sample sizes. We established a data-sharing and collaborative interdisciplinary initiative, the STRESS-NL database, which combines (neuro)biological, physiological, and behavioral data across many acute stress studies in order to accelerate our understanding of the human acute stress response in health and disease (www.stressdatabase.eu). Researchers in the stress field from 12 Dutch research groups of 6 Dutch universities created a database to achieve an accurate inventory of (neuro)biological, physiological, and behavioral data from laboratory-based human studies that used acute stress tests. Currently, the STRESS-NL database consists of information on 5529 individual participants (2281 females and 3348 males, age range 6-99 years, mean age 27.7 ± 16 years) stemming from 57 experiments described in 42 independent studies. Studies often did not use the same stress paradigm; outcomes were different and measured at different time points. All studies currently included in the database assessed cortisol levels before, during and after experimental stress, but cortisol measurement will not be a strict requirement for future study inclusion. Here, we report on the creation of the STRESS-NL database and infrastructure to illustrate the potential of accumulating and combining existing data to allow meta-analytical, proof-of-principle analyses. The STRESS-NL database creates a framework that enables human stress research to take new avenues in explorative and hypothesis-driven data analyses with high statistical power. Future steps could be to incorporate new studies beyond the borders of the Netherlands; or build similar databases for experimental stress studies in rodents. In our view, there are major scientific benefits in initiating and maintaining such international efforts.

Early-life stress exposure and large-scale covariance brain networks in extremely preterm-born infants

The stressful extrauterine environment following premature birth likely has far-reaching and persistent adverse consequences. The effects of early "third-trimester" ex utero stress on large-scale brain networks' covariance patterns may provide a potential avenue to understand how early-life stress following premature birth increases risk or resilience. We evaluated the impact of early-life stress exposure (e.g., quantification of invasive procedures) on maturational covariance networks (MCNs) between 30 and 40 weeks of gestational age in 180 extremely preterm-born infants (<28 weeks of gestation; 43.3% female). We constructed MCNs using covariance of gray matter volumes between key nodes of three large-scale brain networks: the default mode network (DMN), executive control network (ECN), and salience network (SN). Maturational coupling was quantified by summating the number of within- and between-network connections. Infants exposed to high stress showed significantly higher SN but lower DMN maturational coupling, accompanied by DMN-SN decoupling. Within the SN, the insula, amygdala, and subthalamic nucleus all showed higher maturational covariance at the nodal level. In contrast, within the DMN, the hippocampus, parahippocampal gyrus, and fusiform showed lower coupling following stress. The decoupling between DMN-SN was observed between the insula/anterior cingulate cortex and posterior parahippocampal gyrus. Early-life stress showed longitudinal network-specific maturational covariance patterns, leading to a reprioritization of developmental trajectories of the SN at the cost of the DMN. These alterations may enhance the ability to cope with adverse stimuli in the short term but simultaneously render preterm-born individuals at a higher risk for stress-related psychopathology later in life.

Basolateral amygdala activation enhances object recognition memory by inhibiting anterior insular cortex activity

Noradrenergic activation of the basolateral amygdala (BLA) by emotional arousal enhances different forms of recognition memory via functional interactions with the insular cortex (IC). Human neuroimaging studies have revealed that the anterior IC (aIC), as part of the salience network, is dynamically regulated during arousing situations. Emotional stimulation first rapidly increases aIC activity but suppresses it in a delayed fashion. Here, we investigated in male Sprague-Dawley rats whether the BLA influence on recognition memory is associated with an increase or suppression of aIC activity during the postlearning consolidation period. We first employed anterograde and retrograde viral tracing and found that the BLA sends dense monosynaptic projections to the aIC. Memory-enhancing norepinephrine administration into the BLA following an object training experience suppressed aIC activity 1 h later, as determined by a reduced expression of the phosphorylated form of the transcription factor cAMP response element-binding (pCREB) protein and neuronal activity marker c-Fos. In contrast, the number of perisomatic γ-aminobutyric acid (GABA)ergic inhibitory synapses per pCREB-positive neuron was significantly increased, suggesting a dynamic up-regulation of GABAergic tone. In support of this possibility, pharmacological inhibition of aIC activity with a GABAergic agonist during consolidation enhanced object recognition memory. Norepinephrine administration into the BLA did not affect neuronal activity within the posterior IC, which receives sparse innervation from the BLA. The evidence that noradrenergic activation of the BLA enhances the consolidation of object recognition memory via a mechanism involving a suppression of aIC activity provides insight into the broader brain network dynamics underlying emotional regulation of memory.

Meta‐analytic evidence for downregulation of the amygdala during working memory maintenance

The amygdala is a region critically implicated in affective processes. Downregulation of the amygdala is one of the hallmarks of successful emotion regulation. Top‐down inhibition of the amygdala is thought to involve activation of the executive control network. This reciprocal relationship, however, is not exclusive to explicit emotion regulation. It has been noted that any cognitively demanding task that activates executive control network may downregulate the amygdala, including a standard working memory task. Such downregulation is likely established in a load‐dependent fashion with more cognitive demand leading to stronger deactivation. Using a coordinate‐based meta‐analysis, we examined whether a standard working memory task downregulates the amygdala similarly to cognitive reappraisal. We found that a standard 2‐back working memory task indeed systematically downregulates the amygdala and that deactivated clusters strongly overlap with those observed during a cognitive reappraisal task. This finding may have consequences for the interpretation of the underlying mechanism of cognitive reappraisal: amygdala downregulation may be related to the cognitively demanding nature of reappraisal and not per se by the act of the reappraisal itself. Moreover, it raises the possibility of applying working memory tasks in clinical settings as an alternative emotion regulation strategy.

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.

Leukocyte methylomic imprints of exposure to the genocide against the Tutsi in Rwanda: a pilot epigenome-wide analysis

Aim & methods: We conducted a pilot epigenome-wide association study of women from Tutsi ethnicity exposed to the genocide while pregnant and their resulting offspring, and a comparison group of women who were pregnant at the time of the genocide but living outside of Rwanda.Results: Fifty-nine leukocyte-derived DNA samples survived quality control: 33 mothers (20 exposed, 13 unexposed) and 26 offspring (16 exposed, 10 unexposed). Twenty-four significant differentially methylated regions (DMRs) were identified in mothers and 16 in children. Conclusions:In utero genocide exposure was associated with CpGs in three of the 24 DMRs: BCOR, PRDM8 and VWDE, with higher DNA methylation in exposed versus unexposed offspring. Of note, BCOR and VWDE show significant correlation between brain and blood DNA methylation within individuals, suggesting these peripherally derived signals of genocide exposure may have relevance to the brain.

Mild early-life stress exaggerates the impact of acute stress on corticolimbic resting-state functional connectivity

Abundant evidence shows that early‐life stress (ELS) predisposes for the development of stress‐related psychopathology when exposed to stressors later in life, but the underlying mechanisms remain unclear. To study predisposing effects of mild ELS on stress sensitivity, we examined in a healthy human population the impact of a history of ELS on acute stress‐related changes in corticolimbic circuits involved in emotional processing (i.e., amygdala, hippocampus and ventromedial prefrontal cortex [vmPFC]). Healthy young male participants (n = 120) underwent resting‐state functional magnetic resonance imaging (fMRI) in two separate sessions (stress induction vs. control). The Childhood Trauma Questionnaire (CTQ) was administered to index self‐reported ELS, and stress induction was verified using salivary cortisol, blood pressure, heart rate and subjective affect. Our findings show that self‐reported ELS was negatively associated with baseline cortisol, but not with the acute stress‐induced cortisol response. Critically, individuals with more self‐reported ELS exhibited an exaggerated reduction of functional connectivity in corticolimbic circuits under acute stress. A mediation analysis showed that the association between ELS and stress‐induced changes in amygdala–hippocampal connectivity became stronger when controlling for basal cortisol. Our findings show, in a healthy sample, that the effects of mild ELS on functioning of corticolimbic circuits only become apparent when exposed to an acute stressor and may be buffered by adaptations in hypothalamic–pituitary–adrenal axis function. Overall, our findings might reveal a potential mechanism whereby even mild ELS might confer vulnerability to exposure to stressors later in adulthood.

Self-regulation of stress-related large-scale brain network balance using real-time fMRI neurofeedback

It has recently been shown that acute stress affects the allocation of neural resources between large-scale brain networks, and the balance between the executive control network and the salience network in particular. Maladaptation of this dynamic resource reallocation process is thought to play a major role in stress-related psychopathology, suggesting that stress resilience may be determined by the retained ability to adaptively reallocate neural resources between these two networks. Actively training this ability could hence be a potentially promising way to increase resilience in individuals at risk for developing stress-related symptomatology. Using real-time functional Magnetic Resonance Imaging, the current study investigated whether individuals can learn to self-regulate stress-related large-scale network balance. Participants were engaged in a bidirectional and implicit real-time fMRI neurofeedback paradigm in which they were intermittently provided with a visual representation of the difference signal between the average activation of the salience and executive control networks, and tasked with attempting to self-regulate this signal. Our results show that, given feedback about their performance over three training sessions, participants were able to (1) learn strategies to differentially control the balance between SN and ECN activation on demand, as well as (2) successfully transfer this newly learned skill to a situation where they (a) did not receive any feedback anymore, and (b) were exposed to an acute stressor in form of the prospect of a mild electric stimulation. The current study hence constitutes an important first successful demonstration of neurofeedback training based on stress-related large-scale network balance - a novel approach that has the potential to train control over the central response to stressors in real-life and could build the foundation for future clinical interventions that aim at increasing resilience.

Disrupted upregulation of salience network connectivity during acute stress in siblings of schizophrenia patients

BACKGROUND

An adaptive neural stress response is essential to adequately cope with a changing environment. It was previously argued that sympathetic/noradrenergic activity during acute stress increases salience network (SN) connectivity and reduces executive control network (ECN) connectivity in healthy controls, with opposing effects in the late aftermath of stress. Altered temporal dynamics of these networks in response to stress are thought to play a role in the development of psychopathology in vulnerable individuals.

METHODS

We exposed male healthy controls (n = 40, mean age = 33.9) and unaffected siblings of schizophrenia patients (n = 39, mean age = 33.2) to the stress or control condition of the trier social stress test and subsequently investigated resting state functional connectivity of the SN and ECN directly after and 1.5 h after stress.

RESULTS

Acute stress resulted in increased functional connectivity within the SN in healthy controls, but not in siblings (group × stress interaction pfwe < 0.05). In the late aftermath of stress, stress reduced functional connectivity within the SN in both groups. Moreover, we found increased functional connectivity between the ECN and the cerebellum in the aftermath of stress in both healthy controls and siblings of schizophrenia patients.

CONCLUSIONS

The results show profound differences between siblings of schizophrenia patients and controls during acute stress. Siblings lacked the upregulation of neural resources necessary to quickly and adequately cope with a stressor. This points to a reduced dynamic range in the sympathetic response, and may constitute a vulnerability factor for the development of psychopathology in this at-risk group.

Psycho-social factors associated with mental resilience in the Corona lockdown

The SARS-CoV-2 pandemic is not only a threat to physical health but is also having severe impacts on mental health. Although increases in stress-related symptomatology and other adverse psycho-social outcomes, as well as their most important risk factors have been described, hardly anything is known about potential protective factors. Resilience refers to the maintenance of mental health despite adversity. To gain mechanistic insights about the relationship between described psycho-social resilience factors and resilience specifically in the current crisis, we assessed resilience factors, exposure to Corona crisis-specific and general stressors, as well as internalizing symptoms in a cross-sectional online survey conducted in 24 languages during the most intense phase of the lockdown in Europe (22 March to 19 April) in a convenience sample of N = 15,970 adults. Resilience, as an outcome, was conceptualized as good mental health despite stressor exposure and measured as the inverse residual between actual and predicted symptom total score. Preregistered hypotheses (osf.io/r6btn) were tested with multiple regression models and mediation analyses. Results confirmed our primary hypothesis that positive appraisal style (PAS) is positively associated with resilience (p < 0.0001). The resilience factor PAS also partly mediated the positive association between perceived social support and resilience, and its association with resilience was in turn partly mediated by the ability to easily recover from stress (both p < 0.0001). In comparison with other resilience factors, good stress response recovery and positive appraisal specifically of the consequences of the Corona crisis were the strongest factors. Preregistered exploratory subgroup analyses (osf.io/thka9) showed that all tested resilience factors generalize across major socio-demographic categories. This research identifies modifiable protective factors that can be targeted by public mental health efforts in this and in future pandemics.

The effect of optimistic expectancies on attention bias: Neural and behavioral correlates

Optimism bias and positive attention bias are important features of healthy information processing. Recent findings suggest dynamic bidirectional optimism-attention interactions, but the underlying neural mechanisms remain to be identified. The current functional magnetic resonance imaging (fMRI) study, therefore, investigated the neural mechanisms underlying causal effects of optimistic expectancies on attention. We hypothesized that expectancies guide attention to confirmatory evidence in the environment, with enhanced salience and executive control network (SN/ECN) activity for unexpected information. Moreover, based on previous findings, we anticipated optimistic expectancies to more strongly impact attention and SN/ECN activity than pessimistic expectancies. Expectancies were induced with visual cues in 50 participants; subsequent attention to reward and punishment was assessed in a visual search task. As hypothesized, cues shortened reaction times to expected information, and unexpected information enhanced SN/ECN activity. Notably, these effects were stronger for optimistic than pessimistic expectancy cues. Our findings suggest that optimistic expectancies involve particularly strong predictions of reward, causing automatic guidance of attention to reward and great surprise about unexpected punishment. Such great surprise may be counteracted by visual avoidance of the punishing evidence, as revealed by prior evidence, thereby reducing the need to update (over)optimistic reward expectancies.

Reward-Related Striatal Responses Following Stress in Healthy Individuals and Patients With Bipolar Disorder

BACKGROUND

Stress has a major impact on the onset and recurrence of mood episodes in bipolar disorder (BD), but the underlying mechanisms remain unknown. Previous studies have shown distinct time-dependent effects of stress on reward processing in healthy individuals. Impaired reward processing is a core characteristic of BD, and altered reward processing during recovery from stress could influence the development and course of bipolar disorder.

METHODS

We investigated brain responses during reward processing 50 minutes after stress using functional magnetic resonance imaging in 40 healthy control subjects and 40 patients with euthymic BD assigned to either an acute stress test (Trier Social Stress Test) or a no-stress condition.

RESULTS

Acute stress increased cortisol levels in both healthy control subjects and patients with BD. Ventral striatal responses to reward outcome were increased in healthy control subjects during stress recovery but not in patients with BD. For anticipation, no differences were found between the groups following stress.

CONCLUSIONS

For the first time, we show altered reward processing in patients with BD during the recovery phase of stress. These data suggest reduced neural flexibility of hedonic signaling in response to environmental challenges. This may increase the susceptibility to stressful life events in the future and play a role in the development of further psychopathology in the longer term.

Unconscious processing of coarse visual information during anticipatory threat

Rapid detection of threats has been proposed to rely on automatic processing of their coarse visual features. However, it remains unclear whether such a mechanism is restricted to detection of threat cues, or whether it reflects a broader sensitivity to even neutral coarse visual information features during states of threat. We used a backward masking task in which participants discriminated the orientation of subliminally presented low (3 cpd) and high (6 cpd) spatial frequency gratings, under threat (of shock) and safe conditions. Visual awareness of the gratings was assessed objectively using an additional localization task. When participants were unaware of the gratings, above chance and improved discrimination of low-spatial frequency gratings was observed under threat compared to safe trials. These findings demonstrate unconscious processing of neutral coarse visual information during threat state, supporting the view that automatic threat detection may rely on a general facilitation of coarse features irrespective of threat content.

At-risk individuals display altered brain activity following stress

Stress is a major risk factor for almost all psychiatric disorders, however, the underlying neurobiological mechanisms remain largely elusive. In healthy individuals, a successful stress response involves an adequate neuronal adaptation to a changing environment. This adaptive response may be dysfunctional in vulnerable individuals, potentially contributing to the development of psychopathology. In the current study, we investigated brain responses to emotional stimuli following stress in healthy controls and at-risk individuals. An fMRI study was conducted in healthy male controls (N = 39) and unaffected healthy male siblings of schizophrenia patients (N = 39) who are at increased risk for the development of a broad range of psychiatric disorders. Brain responses to pictures from the International Affective Picture System (IAPS) were measured 33 min after exposure to stress induced by the validated trier social stress test (TSST) or a control condition. Stress-induced levels of cortisol, alpha-amylase, and subjective stress were comparable in both groups. Yet, stress differentially affected brain responses of schizophrenia siblings versus controls. Specifically, control subjects, but not schizophrenia siblings, showed reduced brain activity in key nodes of the default mode network (PCC/precuneus and mPFC) and salience network (anterior insula) as well as the STG, MTG, MCC, vlPFC, precentral gyrus, and cerebellar vermis in response to all pictures following stress. These results indicate that even in the absence of a psychiatric disorder, at-risk individuals display abnormal functional activation following stress, which in turn may increase their vulnerability and risk for adverse outcomes.

Visuocortical changes during a freezing-like state in humans

An adaptive response to threat requires optimized detection of critical sensory cues. This optimization is thought to be aided by freezing - an evolutionarily preserved defensive state of immobility characterized by parasympathetically mediated fear bradycardia and regulated by the amygdala-periaqueductal grey (PAG) circuit. Behavioral observations in humans and animals have suggested that freezing is also a state of enhanced visual sensitivity, particularly for coarse visual information, but the underlying neural mechanisms remain unclear. We induced a freezing-like state in healthy volunteers using threat of electrical shock and measured threat-related changes in both stimulus-independent (baseline) and stimulus-evoked visuocortical activity to low-vs. high-spatial frequency gratings, using functional MRI. As measuring immobility is not feasible in MRI environments, we used fear bradycardia and amygdala-PAG coupling in inferring a freezing-like state. An independent functional localizer and retinotopic mapping were used to assess the retinotopic specificity of visuocortical modulations. We found a threat-induced increase in baseline (stimulus-independent) visuocortical activity that was retinotopically nonspecific, which was accompanied by increased connectivity with the amygdala. A positive correlation between visuocortical activity and fear bradycardia (while controlling for sympathetic activation), and a concomitant increase in amygdala-PAG connectivity, confirmed the specificity of these findings for the parasympathetically dominated freezing-like state. Visuocortical responses to gratings were retinotopically specific, but did not differ between threat and safe conditions across participants. However, individuals who exhibited better discrimination of low-spatial frequency stimuli showed reduced stimulus-evoked V1 responses under threat. Our findings suggest that a defensive state of freezing involves an integration of preparatory defensive and perceptual changes which may be regulated by a common mechanism involving the amygdala.

Cognitive benefit and cost of acute stress is differentially modulated by individual brain state

Acute stress is associated with beneficial as well as detrimental effects on cognition in different individuals. However, it is not yet known how stress can have such opposing effects. Stroop-like tasks typically show this dissociation: stress diminishes speed, but improves accuracy. We investigated accuracy and speed during a stroop-like task of 120 healthy male subjects after an experimental stress induction or control condition in a randomized, counter-balanced cross-over design; we assessed brain–behavior associations and determined the influence of individual brain connectivity patterns on these associations, which may moderate the effect and help identify stress resilience factors. In the mean, stress was associated to increase in accuracy, but decrease in speed. Accuracy was associated to brain activation in a distributed set of brain regions overlapping with the executive control network (ECN) and speed to temporo-parietal activation. In line with a stress-related large-scale network reconfiguration, individuals showing an upregulation of the salience and down-regulation of the executive-control network under stress displayed increased speed, but decreased performance. In contrast, individuals who upregulate their ECN under stress show improved performance. Our results indicate that the individual large-scale brain network balance under acute stress moderates cognitive consequences of threat.

Persistence of Amygdala-Hippocampal Connectivity and Multi-Voxel Correlation Structures During Awake Rest After Fear Learning Predicts Long-Term Expression of Fear

After encoding, memories undergo a process of consolidation that determines long-term retention. For conditioned fear, animal models postulate that consolidation involves reactivations of neuronal assemblies supporting fear learning during postlearning "offline" periods. However, no human studies to date have investigated such processes, particularly in relation to long-term expression of fear. We tested 24 participants using functional MRI on 2 consecutive days in a fear conditioning paradigm involving 1 habituation block, 2 acquisition blocks, and 2 extinction blocks on day 1, and 2 re-extinction blocks on day 2. Conditioning blocks were preceded and followed by 4.5-min rest blocks. Strength of spontaneous recovery of fear on day 2 served as a measure of long-term expression of fear. Amygdala connectivity primarily with hippocampus increased progressively during postacquisition and postextinction rest on day 1. Intraregional multi-voxel correlation structures within amygdala and hippocampus sampled during a block of differential fear conditioning furthermore persisted after fear learning. Critically, both these main findings were stronger in participants who exhibited spontaneous recovery 24 h later. Our findings indicate that neural circuits activated during fear conditioning exhibit persistent postlearning activity that may be functionally relevant in promoting consolidation of the fear memory.

Memory Contextualization: The Role of Prefrontal Cortex in Functional Integration across Item and Context Representational Regions

Memory recall is facilitated when retrieval occurs in the original encoding context. This context dependency effect likely results from the automatic binding of central elements of an experience with contextual features (i.e., memory "contextualization") during encoding. However, despite a vast body of research investigating the neural correlates of explicit associative memory, the neural interactions during encoding that predict implicit context-dependent memory remain unknown. Twenty-six participants underwent fMRI during encoding of salient stimuli (faces), which were overlaid onto unique background images (contexts). To index subsequent context-dependent memory, face recognition was tested either in intact or rearranged contexts, after scanning. Enhanced face recognition in intact relative to rearranged contexts evidenced successful memory contextualization. Overall subsequent memory effects (brain activity predicting whether items were later remembered vs. forgotten) were found in the left inferior frontal gyrus (IFG) and right amygdala. Effective connectivity analyses showed that stronger context-dependent memory was associated with stronger coupling of the left IFG with face- and place-responsive areas, both within and between participants. Our findings indicate an important role for the IFG in integrating information across widespread regions involved in the representation of salient items and contextual features.

How the brain connects in response to acute stress: A review at the human brain systems level

The brain's response to stress is a matter of extensive neurocognitive research in an attempt to unravel the mechanistic underpinnings of neural adaptation. In line with the broadly defined concept of acute stress, a wide variety of induction procedures are used to mimic stress experimentally. We set out to review commonalities and diversities of the stress-related functional activity and connectivity changes of functional brain networks in healthy adults across procedures. The acute stress response is consistently associated with both increased activity and connectivity in the salience network (SN) and surprisingly also with increased activity in the default mode network (DMN), while most studies show no changes in the central executive network. These results confirm earlier findings of an essential, coordinating role of the SN in the acute stress response and indicate a dynamic role of the DMN whose function is less clear. Moreover, paradigm specific brain responses have to be taken into account when investigating the role and the within and between network connectivity of these three networks.

Intrinsic functional connectivity between amygdala and hippocampus during rest predicts enhanced memory under stress

Declarative memories of stressful events are less prone to forgetting than mundane events. Animal research has demonstrated that such stress effects on consolidation of hippocampal-dependent memories require the amygdala. In humans, it has been shown that during learning, increased amygdala-hippocampal interactions are related to more efficient memory encoding. Animal models predict that following learning, amygdala-hippocampal interactions are instrumental to strengthening the consolidation of such declarative memories. Whether this is the case in humans is unknown and remains to be empirically verified. To test this, we analyzed data from a sample of 120 healthy male participants who performed an incidental encoding task and subsequently underwent resting-state functional MRI in a stressful and a neutral context. Stress was assessed by measures of salivary cortisol, blood pressure, heart rate, and subjective ratings. Memory was tested afterwards outside of the scanner. Our data show that memory was stronger in the stress context compared to the neutral context and that stress-induced cortisol responses were associated with this memory enhancement. Interestingly, amygdala-hippocampal connectivity during post-encoding awake rest regardless of context (stress or neutral) was associated with the enhanced memory performance under stress. Thus, our findings are in line with a role for intrinsic functional connectivity during rest between the amygdala and the hippocampus in the state effects of stress on strengthening memory.

Freezing promotes perception of coarse visual features

Freezing is an evolutionarily preserved defensive behavior, characterized by immobility and heart rate deceleration, which is thought to promote visual perception. Rapid perceptual assessment of threat is crucial in life-threatening situations; for example, when policemen need to make split-second decisions about the use of deadly force. Here, we hypothesized that freezing is specifically associated with better perception of rapidly processed coarse, low-spatial frequency (LSF) features. We used a visual discrimination task in which participants determined the orientation of LSF and high-spatial frequency (HSF) gratings under threat of shock and safe conditions. As predicted, threat anticipation improved perception of LSF at the expense of HSF gratings. Crucially, stronger decrease in heart rate, a parasympathetic physiological index of freezing, was linked to better perception of LSF. These results provide empirical evidence for the comobilization of physiological and perceptual processes, which may play an important role in decision making under acute stress.

Testosterone reduces functional connectivity during the 'Reading the Mind in the Eyes' Test

Women on average outperform men in cognitive-empathic abilities, such as the capacity to infer motives from the bodily cues of others, which is vital for effective social interaction. The steroid hormone testosterone is thought to play a role in this sexual dimorphism. Strikingly, a previous study shows that a single administration of testosterone in women impairs performance on the 'Reading the Mind in Eyes' Test (RMET), a task in which emotions have to be inferred from the eye-region of a face. This effect was mediated by the 2D:4D ratio, the ratio between the length of the index and ring finger, a proxy for fetal testosterone. Research in typical individuals, in individuals with autism spectrum conditions (ASC), and in individuals with brain lesions has established that performance on the RMET depends on the left inferior frontal gyrus (IFG). Using functional magnetic resonance imaging (fMRI), we found that a single administration of testosterone in 16 young women significantly altered connectivity of the left IFG with the anterior cingulate cortex (ACC) and the supplementary motor area (SMA) during RMET performance, independent of 2D:4D ratio. This IFG-ACC-SMA network underlies the integration and selection of sensory information, and for action preparation during cognitive empathic behavior. Our findings thus reveal a neural mechanism by which testosterone can impair emotion-recognition ability, and may link to the symptomatology of ASC, in which the same neural network is implicated.

Disentangling the roles of arousal and amygdala activation in emotional declarative memory

A large body of evidence in animals and humans implicates the amygdala in promoting memory for arousing experiences. Although the amygdala can trigger threat-related noradrenergic-sympathetic arousal, in humans amygdala activation and noradrenergic-sympathetic arousal do not always concur. This raises the question how these two processes play a role in enhancing emotional declarative memory. This study was designed to disentangle these processes in a combined subsequent-memory/fear-conditioning paradigm with neutral items belonging to two conceptual categories as conditioned stimuli. Functional MRI, skin conductance (index of sympathetic activity), and pupil dilation (indirect index of central noradrenergic activity) were acquired throughout procedures. Recognition memory for individual items was tested 24 h later. We found that pupil dilation and skin conductance responses were higher on CS+ (associated with a shock) compared with CS- trials, irrespective of later memory for those items. By contrast, amygdala activity was only higher for CS+ items that were later confidently remembered compared with CS+ items that were later forgotten. Thus, amygdala activity and not noradrenergic-sympathetic arousal, predicted enhanced declarative item memory. This dissociation is in line with animal models stating that the amygdala integrates arousal-related neuromodulatory changes to alter mnemonic processes elsewhere in the brain.

Altered functional connectivity of the amygdaloid input nuclei in adolescents and young adults with autism spectrum disorder: a resting state fMRI study

BACKGROUND

Amygdala dysfunction is hypothesized to underlie the social deficits observed in autism spectrum disorders (ASD). However, the neurobiological basis of this hypothesis is underspecified because it is unknown whether ASD relates to abnormalities of the amygdaloid input or output nuclei. Here, we investigated the functional connectivity of the amygdaloid social-perceptual input nuclei and emotion-regulation output nuclei in ASD versus controls.

METHODS

We collected resting state functional magnetic resonance imaging (fMRI) data, tailored to provide optimal sensitivity in the amygdala as well as the neocortex, in 20 adolescents and young adults with ASD and 25 matched controls. We performed a regular correlation analysis between the entire amygdala (EA) and the whole brain and used a partial correlation analysis to investigate whole-brain functional connectivity uniquely related to each of the amygdaloid subregions.

RESULTS

Between-group comparison of regular EA correlations showed significantly reduced connectivity in visuospatial and superior parietal areas in ASD compared to controls. Partial correlation analysis revealed that this effect was driven by the left superficial and right laterobasal input subregions, but not the centromedial output nuclei.

CONCLUSIONS

These results indicate reduced connectivity of specifically the amygdaloid sensory input channels in ASD, suggesting that abnormal amygdalo-cortical connectivity can be traced down to the socio-perceptual pathways.

How the amygdala affects emotional memory by altering brain network properties

The amygdala has long been known to play a key role in supporting memory for emotionally arousing experiences. For example, classical fear conditioning depends on neural plasticity within this anterior medial temporal lobe region. Beneficial effects of emotional arousal on memory, however, are not restricted to simple associative learning. Our recollection of emotional experiences often includes rich representations of, e.g., spatiotemporal context, visceral states, and stimulus-response associations. Critically, such memory features are known to bear heavily on regions elsewhere in the brain. These observations led to the modulation account of amygdala function, which postulates that amygdala activation enhances memory consolidation by facilitating neural plasticity and information storage processes in its target regions. Rodent work in past decades has identified the most important brain regions and neurochemical processes involved in these modulatory actions, and neuropsychological and neuroimaging work in humans has produced a large body of convergent data. Importantly, recent methodological developments make it increasingly realistic to monitor neural interactions underlying such modulatory effects as they unfold. For instance, functional connectivity network modeling in humans has demonstrated how information exchanges between the amygdala and specific target regions occur within the context of large-scale neural network interactions. Furthermore, electrophysiological and optogenetic techniques in rodents are beginning to make it possible to quantify and even manipulate such interactions with millisecond precision. In this paper we will discuss that these developments will likely lead to an updated view of the amygdala as a critical nexus within large-scale networks supporting different aspects of memory processing for emotionally arousing experiences.

Testosterone administration in women increases amygdala responses to fearful and happy faces

Data from both rodents and humans show that testosterone reduces fear. This effect is hypothesized to result from testosterone's down regulating effects on the amygdala, a key region in the detection of threat and instigator of fight-or-flight behavior. However, neuroimaging studies employing testosterone administration in humans have consistently shown increased amygdala responsivity. Yet, no study to date has investigated specifically how testosterone affects the amygdala response to fearful emotional expressions. Such stimuli signal the presence of environmental threat and elicit robust amygdala responses that have consistently been associated with anxious traits. In the present study, we therefore used functional magnetic resonance imaging combined with a single administration of 0.5mg testosterone in 12 healthy women to assess testosterone's effects on amygdala responses to dynamic fearful (and happy control) faces. Our results show that both stimuli activate the amygdala. Notably, testosterone increased the amygdala response to both stimuli, and to an equal degree. Thus, testosterone appears not to reduce fear by attenuating the amygdala response toward signals of threat. Data further show that testosterone selectively increases activation of the superficial amygdala (SFA) and, to a lesser extent, the basolateral amygdala (BLA). No effect was found in the central nucleus, which is involved in the generation of autonomic fear responses. Both the SFA and BLA are considered input regions, and enhanced activation by testosterone might reflect the role of this hormone in adaptive responding to socially relevant stimuli. Furthermore, literature on the distinct roles of the SFA and BLA in fear processing show that increased activation of these subregions of the amygdala is consistent with a fear reducing effect of testosterone.

Dynamically changing effects of corticosteroids on human hippocampal and prefrontal processing

Stress has a powerful impact on memory. Corticosteroids, released in response to stress, are thought to mediate, at least in part, these effects by affecting neuronal plasticity in brain regions involved in memory formation, including the hippocampus and prefrontal cortex. Animal studies have delineated aspects of the underlying physiological mechanisms, revealing rapid, nongenomic effects facilitating synaptic plasticity, followed several hours later by a gene-mediated suppression of this plasticity. Here, we tested the hypothesis that corticosteroids would also rapidly upregulate and slowly downregulate brain regions critical for episodic memory formation in humans. To target rapid and slow effects of corticosteroids on neural processing associated with memory formation, we investigated 18 young, healthy men who received 20 mg hydrocortisone either 30 or 180 min before a memory encoding task in a double-blind, placebo-controlled, counter-balanced, crossover design. We used functional MRI to measure neural responses during these memory encoding sessions, which were separated by a month. Results revealed that corticosteroids' slow effects reduced both prefrontal and hippocampal responses, while no significant rapid actions of corticosteroids were observed. Thereby, this study provides initial evidence for dynamically changing corticosteroid effects on brain regions involved in memory formation in humans.

Stress-related noradrenergic activity prompts large-scale neural network reconfiguration

Acute stress shifts the brain into a state that fosters rapid defense mechanisms. Stress-related neuromodulators are thought to trigger this change by altering properties of large-scale neural populations throughout the brain. We investigated this brain-state shift in humans. During exposure to a fear-related acute stressor, responsiveness and interconnectivity within a network including cortical (frontoinsular, dorsal anterior cingulate, inferotemporal, and temporoparietal) and subcortical (amygdala, thalamus, hypothalamus, and midbrain) regions increased as a function of stress response magnitudes. β-adrenergic receptor blockade, but not cortisol synthesis inhibition, diminished this increase. Thus, our findings reveal that noradrenergic activation during acute stress results in prolonged coupling within a distributed network that integrates information exchange between regions involved in autonomic-neuroendocrine control and vigilant attentional reorienting.

The effect of moderate acute psychological stress on working memory-related neural activity is modulated by a genetic variation in catecholaminergic function in humans

Acute stress has an important impact on higher-order cognitive functions supported by the prefrontal cortex (PFC) such as working memory (WM). In rodents, such effects are mediated by stress-induced alterations in catecholaminergic signaling, but human data in support of this notion is lacking. A common variation in the gene encoding Catechol-O-methyltransferase (COMT) is known to affect basal catecholaminergic availability and PFC functions. Here, we investigated whether this genetic variation (Val158Met) modulates effects of stress on WM-related neural activity in humans. In a counterbalanced crossover design, 41 healthy young men underwent functional magnetic resonance imaging (fMRI) while performing a numerical N-back WM task embedded in a stressful or neutral context. Moderate psychological stress was induced by a well-controlled procedure involving viewing strongly aversive (versus emotionally neutral) movie material in combination with a self-referencing instruction. Acute stress resulted in genotype-dependent effects on WM performance and WM-related activation in the dorsolateral PFC, with a relatively negative impact of stress in COMT Met-homozygotes as opposed to a relatively positive effect in Val-carriers. A parallel interaction was found for WM-related deactivation in the anterior medial temporal lobe (MTL). Our findings suggest that individuals with higher baseline catecholaminergic availability (COMT Met-homozygotes) appear to reach a supraoptimal state under moderate levels of stress. In contrast, individuals with lower baselines (Val-carriers) may reach an optimal state. Thus, our data show that effects of acute stress on higher-order cognitive functions vary depending on catecholaminergic availability at baseline, and thereby corroborate animal models of catecholaminergic signaling that propose a non-linear relationship between catecholaminergic activity and prefrontal functions.

Menstrual cycle-related changes in amygdala morphology are associated with changes in stress sensitivity

Premenstrual increases in negative mood are thought to arise from changes in gonadal hormone levels, presumably by influencing mood regulation and stress sensitivity. The amygdala plays a major role in this context, and animal studies suggest that gonadal hormones influence its morphology. Here, we investigated whether amygdala morphology changes over the menstrual cycle and whether this change explains differences in stress sensitivity. Twenty-eight young healthy women were investigated once during the premenstrual phase and once during the late follicular phase. T1-weighted anatomical images of the brain were acquired using magnetic resonance imaging and analyzed with optimized voxel-based morphometry. To measure mood regulation and stress sensitivity, negative affect was assessed after viewing strongly aversive as well as neutral movie clips. Our results show increased gray matter volume in the dorsal part of the left amygdala during the premenstrual phase when compared with the late follicular phase. This volume increase was positively correlated with the premenstrual increase in stress-induced negative affect. This is the first study showing structural plasticity of the amygdala in humans at the macroscopic level that is associated with both endogenous gonadal hormone fluctuations and stress sensitivity. These results correspond with animal findings of gonadal hormone-mediated neural plasticity in the amygdala and have implications for understanding the pathogenesis of specific mood disorders associated with hormonal fluctuations.

Prefrontal mechanisms of fear reduction after threat offset

INTRODUCTION

Reducing fear when a threat has disappeared protects against a continuously elevated anxiety state. In this study, we investigated the brain mechanism involved in this process.

METHODS

The threat paradigm consisted of discrete cues that signaled either threat of shock or safety. Healthy participants were tested in two sessions in which eyeblink startle (n = 26) and blood oxygen level dependence (n = 23) were measured to index subjects' defensive state and brain responses respectively.

RESULTS

Startle results indicated that subjects could rapidly decrease their defensive state after the offset of shock threat. Functional magnetic resonance imaging data indicated that the termination of threat was associated with the recruitment of lateral and ventromedial prefrontal cortices. An exploratory connectivity analysis showed that activity in these prefrontal regions was linked and was also associated with activity in brain regions typically responding to threat, the right anterior insula and amygdala.

CONCLUSIONS

These results provide first evidence for a prefrontal mechanism that functions to control anxiety after threat offset, which may be dysfunctional in patients who suffer from excessive sustained anxiety. Moreover, the results support a model in which the lateral prefrontal cortex controls anxiety related limbic activity through connections with ventromedial prefrontal cortex.

Changes in functioning of mesolimbic incentive processing circuits during the premenstrual phase

The premenstrual phase of the menstrual cycle is associated with marked changes in normal and abnormal motivated behaviors. Animal studies suggest that such effects may result from actions of gonadal hormones on the mesolimbic dopamine (DA) system. We therefore investigated premenstrual changes in reward-related neural activity in terminal regions of the DA system in humans. Twenty-eight healthy young women underwent functional magnetic resonance imaging on 2 days during the menstrual cycle, once during the late follicular phase and once during the premenstrual phase, in counterbalanced order. Using a modified version of the monetary incentive delay task, we assessed responsiveness of the ventral striatum to reward anticipation. Our results show enhanced ventral striatal responses during the premenstrual as compared to the follicular phase. Moreover, this effect was most pronounced in women reporting more premenstrual symptoms. These findings provide support for the notion that changes in functioning of mesolimbic incentive processing circuits may underlie premenstrual changes in motivated behaviors. Notably, increases in reward-cue responsiveness have previously been associated with DA withdrawal states. Our findings therefore suggest that the sharp decline of gonadal hormone levels in the premenstrual phase may trigger a similar withdrawal-like state.

Acute stress modulates genotype effects on amygdala processing in humans

Probing gene-environment interactions that affect neural processing is crucial for understanding individual differences in behavior and disease vulnerability. Here, we tested whether the current environmental context, which affects the acute brain state, modulates genotype effects on brain function in humans. We manipulated the context by inducing acute psychological stress, which increases noradrenergic activity, and probed its effect on tonic activity and phasic responses in the amygdala using two MRI techniques: conventional blood oxygen level-dependent functional MRI and arterial spin labeling. We showed that only carriers of a common functional deletion in ADRA2B, the gene coding for the alpha2b-adrenoreceptor, displayed increased phasic amygdala responses under stress. Tonic activity, reflecting the perfusion of the amygdala, increased independently of genotype after stress induction. Thus, when tonic activity was heightened by stress, only deletion carriers showed increased amygdala responses. Our results demonstrate that genetic effects on brain operations can be state dependent, such that they only become apparent under specific, often environmentally controlled, conditions.

Gray's BIS/BAS dimensions in non-comorbid, non-medicated social anxiety disorder

Gray's behavioural inhibition and behavioural activation (BIS/BAS) neural systems model has led to research on approach and withdrawal as the two most fundamental dimensions of affective behaviour, and their role in psychopathology. Although Gray proposed the BIS as the neurological basis of anxiety, there are no reports examining approach and withdrawal predispositions in social anxiety disorder. Here we report approach and withdrawal predispositions in a group of 23 non-medicated individuals with social anxiety disorder (SAD) without co-morbid depression and in 48 normal controls. Results show increased BIS and decreased BAS fun-seeking in SAD subjects thereby underscoring Gray's dimensional model.

Testosterone administration modulates neural responses to crying infants in young females

Parental responsiveness to infant vocalizations is an essential mechanism to ensure parental care, and its importance is reflected in a specific neural substrate, the thalamocingulate circuit, which evolved through mammalian evolution subserving this responsiveness. Recent studies using functional Magnetic Resonance Imaging (fMRI) provide compelling evidence for a comparable mechanism in humans by showing thalamocingulate responses to infant crying. Furthermore, possibly acting on this common neural substrate, steroid hormones such as estradiol and testosterone, seem to mediate parental behavior both in humans and other animals. Estradiol unmistakably increases parental care, while data for testosterone are less unequivocal. In humans and several other animals, testosterone levels decrease both in mothers and fathers during parenthood. However, exogenous testosterone in mice seems to increase parenting, and infant crying leads to heightened testosterone levels in human males. Not only is the way in which testosterone is implicated in parental responsiveness unresolved, but the underlying mechanisms are fully unknown. Accordingly, using fMRI, we measured neural responses of 16 young women who were listening to crying infants in a double blind, placebo-controlled, counterbalanced, testosterone administration experiment. Crucially, heightened activation in the testosterone condition compared to placebo was shown in the thalamocingulate region, insula, and the cerebellum in response to crying. Our results by controlled hormonal manipulation confirm a role of the thalamocingulate circuit in infant cry perception. Furthermore, the data also suggest that exogenous testosterone, by itself or by way of its metabolite estradiol, in our group of young women acted on this thalamocinculate circuit to, provisionally, upregulate parental care.