Intolerance of uncertainty predicts fear extinction in amygdala-ventromedial prefrontal cortical circuitry

Multimodal assessment of the role of intolerance of uncertainty in fear acquisition and extinction

Personality traits linked to internalizing disorders influence the way we develop fears, but also how we regain a sense of safety. In the present study, we investigated the effect of intolerance of uncertainty (IU) on defensive responses using a differential fear conditioning protocol with an extinction phase. The conditioned stimulus was associated with an aversive sound (90 dB) in 75 % of the presentations during acquisition. A final sample of 176 participants completed the experiment. We measured self-reports of associative (expectancy of the unconditioned stimulus in acquisition) and evaluative learning (arousal and valence), and both physiological (skin conductance response) and electrocortical responses (steady-state visually evoked potentials, ssVEPs; late positive potentials, LPP) to the conditioned stimuli. Our results show that IU's impact is limited, with no effect in both acquisition and extinction. These findings emphasize the necessity of large samples in research on inter-individual differences and contribute to our understanding of how IU may or may not be involved in fear and safety learning processes considering multiple aspects of fear responding.

The impact of the left inferior frontal gyrus on fear extinction: A transcranial direct current stimulation study

INTRODUCTION

Fear extinction is a fundamental component of exposure-based therapies for anxiety-related disorders. The renewal of fear in a different context after extinction highlights the importance of contextual factors. In this study, we aimed to investigate the causal role of the left inferior frontal gyrus (LiFG) in the context-dependency of fear extinction learning via administration of transcranial direct current stimulation (tDCS) over this area.

METHODS

180 healthy subjects were assigned to 9 groups: 3 tDCS conditions (anodal, cathodal, and sham) × 3 context combinations (AAA, ABA, and ABB). The fear conditioning/extinction task was conducted over three consecutive days: acquisition, extinction learning, and extinction recall. tDCS (2 mA, 10min) was administered during the extinction learning phase over the LiFG via a 4-electrode montage. Skin conductance response (SCR) data and self-report assessments were collected.

RESULTS

During the extinction learning phase, groups with excitability-enhancing anodal tDCS showed a significantly higher fear response to the threat cues compared to cathodal and sham stimulation conditions, irrespective of contextual factors. This effect was stable until the extinction recall phase. Additionally, excitability-reducing cathodal tDCS caused a significant decrease of the response difference between the threat and safety cues during the extinction recall phase. The self-report assessments showed no significant differences between the conditions throughout the experiment.

CONCLUSION

Independent of the context, excitability enhancement of the LiFG did impair fear extinction, and led to preservation of fear memory. In contrast, excitability reduction of this area enhanced fear extinction retention. These findings imply that the LiFG plays a role in the fear extinction network, which seems to be however context-independent.

Itsy bitsy spider: Fear and avoidance (generalization) in a free-exploratory virtual reality paradigm

Most experimental avoidance paradigms lack either control over the experimental situation or simplify real-life avoidance behavior to a great extent, making it difficult to generalize the results to the complex approach-avoidance situations that anxious individuals face in daily life. The current study aimed to examine the usability of our recently developed free-exploratory avoidance paradigm in Virtual Reality (VR) that allows for the assessment of subjective as well as behavioral avoidance in participants with varying levels of spider fear. In a VR escape room, participants searched for cues to decipher a code-locked door. Opening a wooden box marked with a post-it note (conditioned stimulus, CS) resulted in exposure to a virtual crawling spider (unconditioned stimulus, US). Avoidance of the original CS and other objects marked with the CS (generalization stimuli, GSs; EXPgen condition) or non-marked (CONT condition) objects was measured via questionnaires and relative manipulation times in a novel room. We expected a positive linear relationship between US aversiveness (levels of spider fear) and (generalization of) fear and avoidance behaviors. Avoidance learning and generalization was demonstrated on both a subjective and behavioral level. Higher levels of spider fear were, overall, related to more negative emotions in response to the encounter with the spider, higher US expectancies for the GSs, and more self-reported and behavioral avoidance of the original CS and the GSs. Finally, we explored relationships between trait anxiety and intolerance of uncertainty and fear and avoidance (generalization), but no robust associations were observed. In conclusion, we confirmed the expected positive linear relationship between spider fear and (generalization of) fear and avoidance behaviors. Our results suggest that our free-exploratory VR avoidance paradigm is well-suited to investigate avoidance behaviors and the generalization of avoidance.

Neural underpinnings of preferential pain learning and the modulatory role of fear

Due to its unique biological relevance, pain-related learning might differ from learning from other aversive experiences. This functional magnetic resonance imaging study compared neural mechanisms underlying the acquisition and extinction of different threats in healthy humans. We investigated whether cue-pain associations are acquired faster and extinguished slower than cue associations with an equally unpleasant tone. Additionally, we studied the modulatory role of stimulus-related fear. Therefore, we used a differential conditioning paradigm, in which somatic heat pain stimuli and unpleasantness-matched auditory stimuli served as US. Our results show stronger acquisition learning for pain- than tone-predicting cues, which was augmented in participants with relatively higher levels of fear of pain. These behavioral findings were paralleled by activation of brain regions implicated in threat processing (insula, amygdala) and personal significance (ventromedial prefrontal cortex). By contrast, extinction learning seemed to be less dependent on the threat value of the US, both on the behavioral and neural levels. Amygdala activity, however, scaled with pain-related fear during extinction learning. Our findings on faster and stronger (i.e. "preferential") pain learning and the role of fear of pain are consistent with the biological relevance of pain and may be relevant to the development or maintenance of chronic pain.

Intolerance of uncertainty enhances generalisation of cued conditioned threat: An event-related potential study

Overgeneralisation is one of the aetiologies of anxiety disorders and is closely associated with elevated intolerance of uncertainty (IU) levels. However, the underlying mechanisms are unclear. Considering the inconsistency of previous results and the high sensitivity of IU to uncertainty, the present study investigated the effect of IU on threat generalisation in predictable and unpredictable conditions. We compared self-reported unconditioned stimuli (US) expectancy and event-related potentials (ERPs) during generalisation in high IU (n = 34) and low IU (n = 35) participants. The results indicated that high IU was associated with higher US expectancy for generalisation stimuli (GS) than with low IU. At the electrophysiological level, compared to low IU, high IU showed increased P1 to ambiguous GS as well as decreased early late positive potential (LPP) to GS in unpredictable conditions, and no differential response to GS in late LPP in predictable conditions. These findings suggest that IU enhances threat generalisation and may be related to increased early automatic attention to ambiguous stimulus and inadequate late elaborate processing in a high uncertainty context. These findings might contribute to the treatment of mood disorders characterized by high IU.

Encoding of conditioned inhibitors of fear in the infralimbic cortex

Cues in the environment signaling the absence of threat, i.e. safety, can influence both fear and reward-seeking behaviors. Heightened and maladaptive fear is associated with reduced activity in the medial prefrontal cortex. We have previously shown in male rats that the infralimbic (IL) prefrontal cortex is necessary for suppressing fear during a safety cue. The objective of the present study was to determine if there was safety cue-specific neural activity within the IL using a Pavlovian conditioning paradigm, where a fear cue was paired with shock, a safety cue was paired with no shock, and a reward cue was paired with sucrose. To investigate how safety cues can suppress fear, the fear and safety cues were presented together as a compound fear + safety cue. Single-unit activity showed a large proportion of neurons with excitatory responses to the fear + safety cue specifically, a separate group of neurons with excitatory responses to both the reward and fear + safety cues, and bidirectional neurons with excitation to the fear + safety cue and inhibition to the fear cue. Neural activity was also found to be negatively correlated with freezing during the fear + safety cue. Together, these data implicate the IL in encoding specific aspects of conditioned inhibitors when fear is being actively suppressed.

Intolerance of uncertainty and functional connectivity of the anterior insula during anticipation of unpredictable reward

Individuals with high intolerance of uncertainty (IU) tend to display maladaptive cognitive, behavioral, physiological, and/or neural responses during anticipation of uncertain or ambiguous outcomes, both positive and negative in valence. Importantly, high IU has been proposed as a key transdiagnostic phenotypic risk factor for the onset and maintenance of several psychiatric disorders. Within the context of reward processing, high IU has been related to dysfunctional reward anticipation, which may be mediated by hyperactive anterior insula (AIC) response to uncertainty. The present study further investigated the relationship between the AIC and IU by examining the association between individual differences in IU and task-based functional connectivity of the right AIC using functional magnetic resonance imaging (fMRI). Participants (N = 171) completed a self-report measure of IU and a reward anticipation task during fMRI. Generalized psychophysiological interaction (gPPI) analyses were performed with a seed in the right AIC. In the U-threat model, we found that greater self-reported levels of IU were correlated with increased functional connectivity between the right AIC and the dorsal anterior cingulate cortex (dACC) and the right dorsolateral prefrontal cortex (dlPFC). In the P-threat model, we did not find these associations, perhaps indicating that they may be more robust during uncertainty. These preliminary findings suggest that parts of salience and central executive control networks may be impacted by and underlie the expression of IU. Future studies should examine the generalizability of these findings to clinical populations and investigate how disruption of these functional networks may contribute to psychopathology.

Neural responding during uncertain threat anticipation in pediatric anxiety

Excessive fear responses to uncertain threat are a key feature of anxiety disorders (ADs), though most mechanistic work considers adults. As ADs onset in childhood and confer risk for later psychopathology, we sought to identify conditions of uncertain threat that distinguish 8-17-year-old youth with AD (n = 19) from those without AD (n = 33), and assess test-retest reliability of such responses in a companion sample of healthy adults across three sites (n = 19). In an adapted uncertainty of threat paradigm, visual cues parametrically signaled threat of aversive stimuli (fear faces) in 25 % increments (0 %, 25 %, 50 %, 100 %), while participants underwent functional magnetic resonance imaging (fMRI). We compared neural response elicited by cues signaling different degrees of probability regarding the subsequent delivery of fear faces. Overall, youth displayed greater engagement of bilateral inferior parietal cortex, fusiform gyrus, and lingual gyrus during uncertain threat anticipation in general. Relative to healthy youth, AD youth exhibited greater activation in ventrolateral prefrontal cortex (vlPFC)/BA47 during uncertain threat anticipation in general. Further, AD differed from healthy youth in scaling of ventral striatum/sgACC activation with threat probability and attenuated flexibility of responding during parametric uncertain threat. Complementing these results, significant, albeit modest, cross-site test-retest reliability in these regions was observed in an independent sample of healthy adults. While preliminary due to a small sample size, these findings suggest that during uncertainty of threat, AD youth engage vlPFC regions known to be involved in fear regulation, response inhibition, and cognitive control. Findings highlight the potential of isolating neural correlates of threat anticipation to guide treatment development and translational work in youth.

Facing Uncertainty: A Comparison of Hierarchical and Variable Exposure Interventions for Contamination Fear

Consistent with the inhibitory retrieval approach, one proposed modification to improve the effectiveness of exposure-based interventions is to maximize variability by not proceeding linearly up an exposure hierarchy. Accordingly, the present study compares hierarchical and variable exposure interventions for contamination-fearful individuals and examines the role of uncertainty to predict intervention outcomes. Participants (N=73) were randomly assigned to complete a single-session exposure intervention using a standard hierarchy or a variable exposure intervention in which hierarchy items were randomly presented. Participants completed a behavioral approach task (BAT) at baseline and two follow-up visits over a two-week period. Both interventions resulted in a significant decrease in anxiety and disgust as well as more BAT steps completed but did not differ from one another. However, individuals in the variable exposure condition reported less variability in uncertainty during exposure compared to those in the standard condition, d=.78. Furthermore, lower levels of variability in uncertainty predicted greater reductions in anxiety and disgust post-intervention. Consistent with previous studies, variable exposure did not convey additional benefit over standard, hierarchical exposure. The experience of uncertainty during exposure is an important yet understudied process that warrants additional investigation.

Intolerance of uncertainty and future career anxiety among Chinese undergraduate students during COVID-19 period: Fear of COVID-19 and depression as mediators

Uncertainty is mushrooming throughout COVID-19, and intolerance of uncertainty (IoU) nudges people into mental health difficulties involving fear, depression, and anxiety. The objective of this study was to investigate the role of depression and fear of COVID-19 (FoC) in the association between IoU and future career anxiety (FCA) among Chinese university students during the COVID-19 pandemic. This study involved 1,919 Chinese undergraduate students from 11 universities in eight Chinese cities with an online self-administered survey that included demographic information, IoU, FoC, depression, and FCA completed by all participants. Our study demonstrated a positive relationship between IoU and FCA and the chain mediation effect of FoC and depression. Thus, understanding how FoC affects FCA not only informs university career professionals and assists students in preparing for employment, but also motivates schools to offer career opportunities workshops and, most importantly, provides mental health support to help students effectively cope with uncertainty and overcome COVID-19-related stress.

Behavioral and neural responses during fear conditioning and extinction in a large transdiagnostic sample

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Behavioral and neural responses during Pavlovian fear learning were examined in a large sample of healthy and individuals with anxiety and depression.

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Latent profile models to threat were derived from behavioral and neural data.

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Demographic, cognitive, and psychological variables did not robustly characterize latent profiles.

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Neuroimaging data did not evidence functional role of amygdala in fear learning.

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Human fear learning recruited a distributed network of regions involved in interoceptive, cognitive, motivational, and psychomotor processes.

Background

Dysregulation of fear learning has been associated with psychiatric disorders that have altered positive and negative valence domain function. While amygdala-insula-prefrontal circuitry is considered important for fear learning, there have been inconsistencies in neural findings in healthy and clinical human samples. This study aimed to delineate the neural substrates and behavioral responses during fear learning in a large, transdiagnostic sample with predominantly depressive and/or anxious dysfunction.

Methods

Two-hundred and eighty-two individuals (52 healthy participants; 230 participants with depression and/or anxiety-related problems) from the Tulsa 1000 study, an ongoing, naturalistic longitudinal study based on a dimensional psychopathological framework, completed a Pavlovian fear learning task during functional magnetic resonance imaging. Linear mixed-effects analyses examined condition-by-time effects on brain activation (CS+, CS- across familiarization, conditioning, and extinction trials). A data-driven latent profile analysis (LPA) examined distinct patterns of behavioral and neural responses to threat across fear conditioning and extinction, while logistic regression analyses evaluated cognitive-affective predictors of latent profiles.

Results

Whole-brain analyses revealed a condition-by-time interaction in the anterior insula, postcentral gyrus, superior temporal gyrus, middle frontal gyrus, and cerebellum but not amygdala. The LPA identified distinct latent profiles across subjective and neural levels of measurement. Anterior insula profiles were characterized by marginal differences in age and state anxiety.

Conclusions

Our findings demonstrate that human fear learning recruits a distributed network of regions involved in interoceptive, cognitive, motivational, and psychomotor processes. Data-driven analyses identified distinct profiles of subjective and neural responses during fear learning that transcended clinical diagnoses, but no robust relationships to demographic or cognitive-affective variable were identified.

A Preliminary Test of Novelty-Facilitated Extinction in Individuals With Pathological Anxiety

Studies with rodents and healthy humans suggest that replacing the expected threat with a novel outcome improves extinction and reduces the return of conditioned fear more effectively than threat omission alone. Because of the potential clinical implications of this finding for exposure-based anxiety treatments, this study tested whether the same was true in individuals with pathological anxiety (i.e., met DSM-5 diagnostic criteria for an anxiety disorder and/or obsessive-compulsive disorder (OCD). In this preliminary test of novelty-facilitated extinction, 51 unmedicated individuals with pathological anxiety were randomized to standard extinction (n = 27) or novelty-facilitated extinction (n = 24). Participants returned 24 h later to test extinction recall and fear reinstatement. Skin conductance responses (SCR) were the dependent measure of conditioned fear. Participants in both groups learned the fear association but variably extinguished it. Novelty did not facilitate extinction in this preliminary trial. Findings underscore the importance of translating paradigms from healthy humans to clinical samples, to ensure that new treatment ideas based on advances in basic neuroscience are relevant to patients.

Intolerance of uncertainty prospectively predicts the transdiagnostic severity of emotional psychopathology: Evidence from a Veteran sample

Intolerance of uncertainty (IU) has been conceptualized as a transdiagnostic vulnerability for emotional psychopathology, but few studies have tested whether it prospectively predicts emotional psychopathology, and none have utilized transdiagnostic and clinician-rated outcomes. To fill this gap, the present study tested whether IU prospectively predicted the clinician-rated severity of transdiagnostic emotional psychopathology six months later in a treatment-seeking Veteran sample. Participants completed the Intolerance of Uncertainty 12-item scale (IUS-12) and the Structured Clinical Interview for the DSM-5 (SCID-5) at Time 1 and again six-months later (Time 2); assessed emotional disorders included both anxiety-related disorders (i.e., post-traumatic stress disorder, generalized anxiety disorder, panic disorder, social anxiety disorder, obsessive compulsive disorder, specific phobia) and depressive conditions (i.e., major depressive disorder and persistent depressive disorder). Linear regression analyses revealed a bidirectional prospective relation between IU and emotional psychopathology, wherein higher Time 1 IUS-12 predicted greater Time 2 emotional disorder severity and greater Time 1 emotional disorder severity predicted higher Time 2 IUS-12. Follow-up analyses revealed that IU prospectively predicted the maintenance (but not the development) of anxiety-related issues, whereas prediction of Time 2 depression was nullified when controlling for Time 1 anxiety pathology. These findings implicate IU as a transdiagnostic vulnerability for emotional psychopathology and suggest the construct can be particularly useful as a treatment target and prognostic indicator for anxiety-related conditions.

Assessment of intolerance of uncertainty: Validation of a modified anagram task

BACKGROUND AND OBJECTIVES

Intolerance of uncertainty (IU) is an individual difference factor that reflects difficulty tolerating emotional distress in the context of uncertainty and is a robust transdiagnostic risk factor for emotional disorders. A limitation of prior research on IU is the heavy reliance on self-report measures to assess this construct. The aim of the present study was to examine the validity of a brief, computerized anagram task modified to assess IU (the PACT Anagram Task; PAT).

METHODS

Participants were 221 unselected undergraduate students (71% female; M_age = 19; 89% Caucasian) who completed the PAT and a series of self-report measures of convergent, discriminant, and incremental validity, and measures of anxiety and depression symptoms online for course credit.

RESULTS

Greater PAT-Distress was positively correlated measures of convergent validity and demonstrated incremental validity in relation to self-reported IU above and beyond attentional control. None of the PAT indicators were associated with compassion or empathic concern, evidencing discriminant validity. PAT-Distress and PAT-Answers were each associated with greater worry above and beyond self-reported IU.

LIMITATIONS

Study limitations include the cross-sectional design and lack of diversity in terms of sample demographics. Furthermore, we did not examine convergence between this task and other behavioral measures of IU.

CONCLUSION

Subjective distress following completion of the PAT may serve as one indicator of IU. Further research is needed in order to replicate these results and validate the use of the PAT in clinical samples.

Intolerance of uncertainty and novelty facilitated extinction: The impact of reinforcement schedule

Individuals who score high in intolerance of uncertainty (IU) display reduced threat extinction. Recently, it was shown that replacing threat associations with novel associations during extinction learning (i.e., presenting a novel tone 100% of the time) can promote threat extinction retention in individuals with high IU. This novelty facilitated extinction (NFE) effect could be driven by the tone's novelty or reliability. Here, we sought to address this question by adjusting the reliability of the novel tone (i.e., the reinforcement rate) during NFE. We measured skin conductance response during an associative learning task in which participants (n = 92) were assigned to one of three experimental groups: standard extinction, NFE 100% reinforcement, or NFE 50% reinforcement. For standard extinction, compared to NFE 100% and 50% reinforcement groups, we observed a trend for greater recovery of the conditioned response during extinction retention. Individuals with high IU relative to low IU in the standard extinction group demonstrated a larger recovery of the conditioned response during extinction retention. These findings tentatively suggest that NFE effects are driven by the novelty rather than the reliability of the new stimulus. The implications of these findings for translational and clinical research in anxiety disorder pathology are discussed.

The effect of social anxiety on the acquisition and extinction of low-cost avoidance

Excessive avoidance and safety behaviours are a hallmark feature of social anxiety disorder. However, the conditioning and extinction of avoidance behaviour in social anxiety is understudied. Here, we examined the effect of individual differences in social anxiety on low-cost operant avoidance conditioning and extinction in 80 female participants. We employed an avoidance conditioning and extinction paradigm and measured skin conductance response, threat expectancy ratings and avoidance behaviour throughout the task. Findings demonstrated that elevated levels of social anxiety predicted the generalisation of conditioned avoidance responses across to safety cues during avoidance conditioning. When the opportunity to avoid was returned after the threat extinction phase, elevated social anxiety was associated with increased avoidance behaviour to threat cues. The results suggest that compromised extinction of avoidance behaviour is a characteristic of social anxiety and supports the strategy of minimising avoidance and safety behaviours during exposure therapy for the treatment of social anxiety disorder. Future research should utilise the avoidance conditioning and extinction paradigm as a laboratory model for clinical research to investigate how, and under what circumstances, the extinction of avoidance and safety behaviours can be improved for individuals high in social anxiety.

I Doubt It Is Safe: A Meta-analysis of Self-reported Intolerance of Uncertainty and Threat Extinction Training

Background

Intolerance of uncertainty (IU), the tendency to find uncertainty distressing, is an important transdiagnostic dimension in mental health disorders. Higher self-reported IU has been linked to poorer threat extinction training (i.e., the updating of threat to safe associations), a key process that is targeted in exposure-based therapies. However, it remains to be seen whether IU-related effects during threat extinction training are reliably and specifically driven by the IU construct or a particular subcomponent of the IU construct over other self-reported measures of anxiety.

Methods

A meta-analysis of studies from different laboratories (18 experiments; sample N = 1006) was conducted on associations between different variants of self-reported IU (i.e., 27-item, 12-item, inhibitory, and prospective subscales), trait anxiety, and threat extinction training via skin conductance response. The specificity of IU and threat extinction training was assessed against measures of trait anxiety.

Results

All the self-reported variants of IU, but not trait anxiety, were associated with threat extinction training via skin conductance response (i.e., continued responding to the old threat cue). Specificity was observed for the majority of self-reported variants of IU over trait anxiety.

Conclusions

The findings suggest that the IU construct broadly accounts for difficulties in threat extinction training and is specific over other measures of self-reported anxiety. These findings demonstrate the robustness and specificity of IU-related effects during threat extinction training and highlight potential opportunities for translational work to target uncertainty in therapies that rely on threat extinction principles such as exposure therapy.

Toward a neurocircuit-based taxonomy to guide treatment of obsessive-compulsive disorder

An important challenge in mental health research is to translate findings from cognitive neuroscience and neuroimaging research into effective treatments that target the neurobiological alterations involved in psychiatric symptoms. To address this challenge, in this review we propose a heuristic neurocircuit-based taxonomy to guide the treatment of obsessive-compulsive disorder (OCD). We do this by integrating information from several sources. First, we provide case vignettes in which patients with OCD describe their symptoms and discuss different clinical profiles in the phenotypic expression of the condition. Second, we link variations in these clinical profiles to underlying neurocircuit dysfunctions, drawing on findings from neuropsychological and neuroimaging studies in OCD. Third, we consider behavioral, pharmacological, and neuromodulatory treatments that could target those specific neurocircuit dysfunctions. Finally, we suggest methods of testing this neurocircuit-based taxonomy as well as important limitations to this approach that should be considered in future research.

Intolerance of uncertainty is associated with heightened responding in the prefrontal cortex during cue-signalled uncertainty of threat

Heightened responding to uncertain threat is considered a hallmark of anxiety disorder pathology. We sought to determine whether individual differences in self-reported intolerance of uncertainty (IU), a key transdiagnostic dimension in anxiety-related pathology, underlies differential recruitment of neural circuitry during cue-signalled uncertainty of threat (n = 42). In an instructed threat of shock task, cues signalled uncertain threat of shock (50%) or certain safety from shock. Ratings of arousal and valence, skin conductance response (SCR), and functional magnetic resonance imaging were acquired. Overall, participants displayed greater ratings of arousal and negative valence, SCR, and amygdala activation to uncertain threat versus safe cues. IU was not associated with greater arousal ratings, SCR, or amygdala activation to uncertain threat versus safe cues. However, we found that high IU was associated with greater ratings of negative valence and greater activity in the medial prefrontal cortex and dorsomedial rostral prefrontal cortex to uncertain threat versus safe cues. These findings suggest that during cue-signalled uncertainty of threat, individuals high in IU rate uncertain threat as aversive and engage prefrontal cortical regions known to be involved in safety-signalling and conscious threat appraisal. Taken together, these findings highlight the potential of IU in modulating safety-signalling and conscious appraisal mechanisms in situations with cue-signalled uncertainty of threat, which may be relevant to models of anxiety-related pathology.

Reliability of web-based affective auditory stimulus presentation

Web-based experimental testing has seen exponential growth in psychology and cognitive neuroscience. However, paradigms involving affective auditory stimuli have yet to adapt to the online approach due to concerns about the lack of experimental control and other technical challenges. In this study, we assessed whether sounds commonly used to evoke affective responses in-lab can be used online. Using recent developments to increase sound presentation quality, we selected 15 commonly used sound stimuli and assessed their impact on valence and arousal states in a web-based experiment. Our results reveal good inter-rater and test-retest reliabilities, with results comparable to in-lab studies. Additionally, we compared a variety of previously used unpleasant stimuli, allowing us to identify the most aversive among these sounds. Our findings demonstrate that affective sounds can be reliably delivered through web-based platforms, which help facilitate the development of new auditory paradigms for affective online experiments.

The role of intolerance of uncertainty in classical threat conditioning: Recent developments and directions for future research

Intolerance of uncertainty (IU), the tendency to find uncertainty aversive, is an important transdiagnostic dimension in mental health disorders. Over the last decade, there has been a surge of research on the role of IU in classical threat conditioning procedures, which serve as analogues to the development, treatment, and relapse of anxiety, obsessive-compulsive, and trauma- and stressor-related disorders. This review provides an overview of the existing literature on IU in classical threat conditioning procedures. The review integrates findings based on the shared or discrete parameters of uncertainty embedded within classical threat conditioning procedures. Under periods of unexpected uncertainty, where threat and safety contingencies change, high IU, over other self-reported measures of anxiety, is specifically associated with poorer threat extinction learning and retention, as well as overgeneralisation. Under periods of estimation and expected uncertainty, where the parameters of uncertainty are being learned or have been learned, such as threat acquisition training and avoidance learning, the findings are mixed for IU. These findings provide evidence that individual differences in IU play a significant role in maintaining learned fear and anxiety, particularly under volatile environments. Recommendations for future research are outlined, with discussion focusing on how parameters of uncertainty can be better defined to capture how IU is involved in the maintenance of learned fear and anxiety. Such work will be crucial for understanding the role of IU in neurobiological models of uncertainty-based maintenance of fear and anxiety and inform translational work aiming to improve the diagnosis and treatment of relevant psychopathology.

Intolerance of uncertainty, and not social anxiety, is associated with compromised extinction of social threat

Extinction-resistant threat is regarded as a central hallmark of pathological anxiety. However, it remains relatively under-studied in social anxiety. Here we sought to determine whether self-reported trait social anxiety is associated with compromised threat extinction learning and retention. We tested this hypothesis within two separate, socially relevant conditioning studies. In the first experiment, a Selective Extinction Through Cognitive Evaluation (SECE) paradigm was used, which included a cognitive component during the extinction phase, while experiment 2 used a traditional threat extinction paradigm. Skin conductance responses and subjective ratings of anxiety (experiment 1 and 2) and expectancy (experiment 2) were collected across both experiments. The findings of both studies demonstrated no effect of social anxiety on extinction learning or retention. Instead, results from experiment 1 indicated that individual differences in Intolerance of Uncertainty (IU) were associated with the ability to use contextual cues to decrease a conditioned response during SECE. However, during extinction retention, high IU predicted greater generalisation across context cues. Findings of experiment 2 revealed that higher IU was associated with impaired extinction learning and retention. The results from both studies suggest that compromised threat extinction is likely to be a characteristic of high levels of IU and not social anxiety.

Effect of Tryptophan Depletion on Conditioned Threat Memory Expression: Role of Intolerance of Uncertainty

Background

Responding emotionally to danger is critical for survival. Normal functioning also requires flexible alteration of emotional responses when a threat becomes safe. Aberrant threat and safety learning occur in many psychiatric disorders, including posttraumatic stress disorder, obsessive-compulsive disorder, and schizophrenia, in which emotional responses can persist pathologically. While there is evidence that threat and safety learning can be modulated by the serotonin systems, there have been few studies in humans. We addressed a critical clinically relevant question: How does lowering serotonin affect memory retention of conditioned threat and safety memory?

Methods

Forty-seven healthy participants underwent conditioning to two stimuli predictive of threat on day 1. One stimulus but not the other was subsequently presented in an extinction session. Emotional responding was assessed by the skin conductance response. On day 2, we employed acute dietary tryptophan depletion to lower serotonin temporarily, in a double-blind, placebo-controlled, randomized between-groups design. We then tested for the retention of conditioned threat and extinction memory. We also measured self-reported intolerance of uncertainty, known to modulate threat memory expression.

Results

The expression of emotional memory was attenuated in participants who had undergone tryptophan depletion. Individuals who were more intolerant of uncertainty showed even greater attenuation of emotion following depletion.

Conclusions

These results support the view that serotonin is involved in predicting aversive outcomes and refine our understanding of the role of serotonin in the persistence of emotional responsivity, with implications for individual differences in vulnerability to psychopathology.

From Uncertainty to Anxiety: How Uncertainty Fuels Anxiety in a Process Mediated by Intolerance of Uncertainty

Uncertainty about future events may lead to worry, anxiety, even inability to function. The highly related concept-intolerance of uncertainty (IU)-emerged in the early 1990s, which is further developed into a transdiagnostic risk factor in multiple forms of anxiety disorders. Interests in uncertainty and intolerance of uncertainty have rapidly increased in recent years; little is known about the construct and phenomenology of uncertainty and IU and the association between them. In an attempt to reveal the nature of two concepts, we reviewed broad literature surrounding uncertainty and intolerance of uncertainty (IU). We followed the process in which the whole IU theory developed and extended, including two aspects: (1) from uncertainty to intolerance of uncertainty and (2) definition of uncertainty and intolerance of uncertainty, and further concluded uncertainty fuels to negative emotions, biased expectancy, and inflexible response. Secondly, this paper summarized the experimental research concerning uncertainty and IU, consisted of three parts: (1) uncertainty-based research, (2) measurements of IU, and (3) domain-specific IU. Lastly, we pointed out what remains unknown and needed to be investigated in future research. This result provides a comprehensive overview in this domain, enhancing our understanding of uncertainty and IU and contributing to further theoretical and empirical explorations.

Over-activation of primate subgenual cingulate cortex enhances the cardiovascular, behavioral and neural responses to threat

Stress-related disorders such as depression and anxiety are characterized by enhanced negative emotion and physiological dysfunction. Whilst elevated activity within area 25 of the subgenual anterior cingulate cortex (sgACC/25) has been implicated in these illnesses, it is unknown whether this over-activity is causal. By combining targeted intracerebral microinfusions with cardiovascular and behavioral monitoring in marmosets, we show that over-activation of sgACC/25 reduces vagal tone and heart rate variability, alters cortisol dynamics during stress and heightens reactivity to proximal and distal threat. ¹⁸F-FDG PET imaging shows these changes are accompanied by altered activity within a network of brain regions including the amygdala, hypothalamus and dorsolateral prefrontal cortex. Ketamine, shown to have rapid antidepressant effects, fails to reverse elevated arousal to distal threat contrary to the beneficial effects we have previously demonstrated on over-activation induced reward blunting, illustrating the symptom-specificity of its actions.

Alexander et al. causally implicate over-activity in primate subgenual cingulate in affective and cardiovascular dysfunction relevant to anxiety and depression. Over-activation led to elevated activity in a stress-related network whilst decreasing activity in higher-order prefrontal cognitive regions.

Individual differences in fear acquisition: multivariate analyses of different emotional negativity scales, physiological responding, subjective measures, and neural activation

Negative emotionality is a well-established and stable risk factor for affective disorders. Individual differences in negative emotionality have been linked to associative learning processes which can be captured experimentally by computing CS-discrimination values in fear conditioning paradigms. Literature suffers from underpowered samples, suboptimal methods, and an isolated focus on single questionnaires and single outcome measures. First, the specific and shared variance across three commonly employed questionnaires [STAI-T, NEO-FFI-Neuroticism, Intolerance of Uncertainty (IU) Scale] in relation to CS-discrimination during fear-acquisition in multiple analysis units (ratings, skin conductance, startle) is addressed (NStudy1 = 356). A specific significant negative association between STAI-T and CS-discrimination in SCRs and between IU and CS-discrimination in startle responding was identified in multimodal and dimensional analyses, but also between latent factors negative emotionality and fear learning, which capture shared variance across questionnaires/scales and across outcome measures. Second, STAI-T was positively associated with CS-discrimination in a number of brain areas linked to conditioned fear (amygdala, putamen, thalamus), but not to SCRs or ratings (NStudy2 = 113). Importantly, we replicate potential sampling biases between fMRI and behavioral studies regarding anxiety levels. Future studies are needed to target wide sampling distributions for STAI-T and verify whether current findings are generalizable to other samples.

Prospective intolerance of uncertainty is associated with maladaptive temporal distribution of avoidance responses: An extension of Flores, López, Vervliet, and Cobos (2018)

BACKGROUND AND OBJECTIVES

Excessive maladaptive avoidance has been claimed to be one of the mechanisms through which intolerance of uncertainty (IU) may play its causal role in the development and maintenance of several anxiety and compulsive disorders. Consistently, Flores et al. (2018) found that individuals with higher Prospective IU (P-IU), a specific IU subfactor, display excessive avoidance response repetitions in a free-operant discriminative task to avoid an aversive noise. In the present study we tested the hypothesis that P-IU not only predicts the amount of avoidance responses but also how well the temporal distribution of such responses fits the temporal distribution of threats.

METHODS

Further correlation and hierarchical regression analysis of Flores et al.'s (2018) data served to test this hypothesis. We evaluated two aspects of the temporal distribution of responses: a) for how long participants were performing the responses; b) the behavioral discrimination between threatening and safe time periods.

RESULTS

The results showed that scoring high in P-IU was positively associated with longer periods of time dedicated to avoiding and with worse behavioral discrimination between threatening and safe time periods. Hierarchical regression analyses indicated that later addition of inhibitory intolerance of uncertainty and trait anxiety did not significantly improved the explained variance.

LIMITATIONS

Our results are exclusively based on the use of a low-cost avoidance response, and the present study does not clarify the precise mechanisms that lead high P-IU people to engage in non-optimal avoidance response distribution through time.

CONCLUSIONS

These results suggest that excessive avoidance is also driven by uncertainty of threat timing and highlight the relevance of P-IU as a vulnerability factor for excessive and outspread avoidance behaviors.

The Impact of Intolerance of Uncertainty and Cognitive Behavioural Instructions on Safety Learning

Background

Difficulty updating threat associations to safe associations has been observed in individuals who score high in self-reported Intolerance of Uncertainty (IU). Here we sought to determine whether an instruction based on fundamental principles of Cognitive Behavioural Therapy could promote safety learning in individuals with higher levels of IU, whilst controlling for self-reported trait anxiety (STICSA).

Methods

We measured skin conductance response, pupil dilation and expectancy ratings during an associative threat learning task in which participants either received a cognitive behavioural instruction or no instruction prior to threat extinction (n = 92).

Results

Analyses revealed that both self-reported IU and STICSA similarly predicted differences in skin conductance response. Only individuals with lower IU/STICSA in the cognitive behavioural instruction condition displayed successful safety learning via skin conductance response.

Conclusions

These initial results provide some insight into how simple cognitive behavioural instructions combined with exposure are applied differently in individuals with varying levels of self-reported anxiety. The results further our understanding of the role of basic cognitive behavioural principles and self-reported anxiety in safety learning.

Intolerance of uncertainty and threat generalization: A replication and extension

Intolerance of uncertainty (IU) is a transdiagnostic risk factor for internalizing disorders. Prior work has found that IU may be associated with either increased reactivity to threat or, alternatively, with decreased differential responding between threat and nonthreat/safety cues (i.e., threat generalization). For example, work by Morriss, Macdonald, & van Reekum  (2016) found that higher IU was associated with increased threat generalization during acquisition (using skin conductance response (SCR)), as well as less differentiation between acquisition and extinction (using subjective uneasiness ratings). Here, three labs attempted direct and conceptual replications of Morriss, Macdonald, et al. (2016). Results showed that the direct replication failed, despite being conducted at the same lab site as the original study; moreover, in contrast to Morriss, Macdonald, et al. (2016), the direct replication found that higher IU was associated with greater SCR discrimination between threat and safety cues (across acquisition and extinction), as well as greater differences in uneasiness ratings between acquisition and extinction. Nonetheless, in the conceptual replications, higher IU was associated with greater threat generalization, as well as less discrimination between acquisition and extinction, as measured using SCR. Higher IU was also associated with larger late positive potentials to threat versus safety cues during extinction-results that mirror those observed by Morriss, Macdonald, et al. (2016) using SCR. Results are discussed with regards to the challenge involved in defining a successful replication attempt, the benefits of collaborative replication and the use and reliability of multiple measures.

The effect of cathodal tDCS on fear extinction: A cross-measures study

BACKGROUND

Extinction-based procedures are often used to inhibit maladaptive fear responses. However, because extinction procedures show efficacy limitations, transcranial direct current stimulation (tDCS) has been suggested as a promising add-on enhancer.

OBJECTIVE

In this study, we tested how cathodal tDCS over the right dorsolateral prefrontal cortex affects extinction and tried to unveil the processes at play that boost the effectiveness of extinction procedures and its translational potential to the treatment of anxiety disorders.

METHODS

We implemented a fear conditioning paradigm whereby 41 healthy women (mean age = 20.51 ± 5.0) were assigned to either cathodal tDCS (n = 27) or sham tDCS (n = 16). Fear responses were measured with self-reports, autonomic responses, and implicit avoidance tendencies.

RESULTS

Cathodal tDCS shows no statistically significant effect in extinction, according to self-reports, and seems to even negatively affect fear conditioned skin conductance responses. However, one to three months after the tDCS session and extinction, we found a group difference in the action tendencies towards the neutral stimuli (F (1, 41) = 12.04, p = .001, ηp2 = .227), with the cathodal tDCS group (as opposed to the sham group) showing a safety learning (a positive bias towards the CS-), with a moderate effect size. This suggests that cathodal tDCS may foster stimuli discrimination, leading to a decreased generalization effect.

DISCUSSION

Cathodal tDCS may have enhanced long-term distinctiveness between threatening cues and perceptively similar neutral cues through a disambiguation process of the value of the neutral stimuli-a therapeutic target in anxiety disorders. Future studies should confirm these results and extend the study of cathodal tDCS effect on short term avoidance tendencies.

The role of threat level and intolerance of uncertainty in extinction

Recent evidence suggests that individual differences in intolerance of uncertainty (IUS) are associated with disrupted threat extinction. However, it is unknown what maintains the learned threat association in high IUS individuals: is it the experienced uncertainty during extinction or the combination of experienced uncertainty with potential threat during extinction? Here we addressed this question by running two independent experiments with uncertain auditory stimuli that varied in threat level (Experiment 1, aversive human scream (n = 30); Experiment 2, neutral tone (n = 47) and mildly aversive tone (n = 49)). During the experiments, we recorded skin conductance responses and subjective ratings to the learned cues during acquisition and extinction. In experiment 1, high IUS was associated with heightened skin conductance responding to the learned threat vs. safe cue during extinction. In experiment 2, high IUS was associated only with larger skin conductance responding to the learned cues with more threatening properties during extinction i.e. mildly aversive tone. These findings suggest that uncertainty in combination with threat, even when mild, disrupts extinction in high IUS individuals. Such findings help us understand the link between IUS and threat extinction, and its relevance to anxiety disorder pathology.

Multimodal evidence for delayed threat extinction learning in adolescence and young adulthood

Previous research in rodents and humans points to an evolutionarily conserved profile of blunted threat extinction learning during adolescence, underpinned by brain structures such as the amygdala and medial prefrontal cortex (mPFC). In this study, we examine age-related effects on the function and structural connectivity of this system in threat extinction learning in adolescence and young adulthood. Younger age was associated with greater amygdala activity and later engagement of the mPFC to learned threat cues as compared to safety cues. Furthermore, greater structural integrity of the uncinate fasciculus, a white matter tract that connects the amygdala and mPFC, mediated the relationship between age and mPFC engagement during extinction learning. These findings suggest that age-related changes in the structure and function of amygdala-mPFC circuitry may underlie the protracted maturation of threat regulatory processes.

Intolerance of uncertainty is associated with reduced attentional inhibition in the absence of direct threat

Intolerance of uncertainty (IU) is a dispositional tendency to find uncertain situations aversive. There is limited understanding as to how IU may bias attention to uncertainty in the absence of direct threat. Here we examined the extent to which uncertain distractors and individual differences in IU impacted eye-movements during an attentional capture task. Participants were asked to move their eyes towards a target, whilst ignoring an array of distractors. An additional distractor could appear before or after the target in a near or far location from the target. We observed high IU individuals to display fewer first saccades to the target in all conditions. The results were specific to IU, over trait anxiety. Overall, these results suggest that IU modulates attention to uncertainty in the absence of direct threat. Such findings inform the conceptualisation of IU and its relation to psychopathology.

Individual differences in anxiety and fear learning: The role of working memory capacity

Anxiety disorders are characterised by the perception of fear and threat in the presence of stimuli that are neutral or ambiguous. Attempts in previous research to explain the relationship between anxiety and fear learning have been inconsistent, possibly due to the influence of an unmeasured mechanism that mediates the relationship between them. Working memory capacity has been suggested as one such mechanism. The current study investigated the influence of anxiety-based individual differences upon associative fear learning, while accounting for individual differences in working memory. We hypothesised that individuals high in both anxiety and working memory would show unimpaired fear learning whereas individuals high in anxiety and low in working memory would exhibit dysfunctional fear learning. Sixty participants completed a battery of anxiety and working memory tests, as well as a fear conditioning experiment that tested for blocking, conditioned inhibition and fear discrimination. We found that anxious individuals were more likely to show impaired fear discrimination only if they also had a low working memory capacity. Furthermore, anxiety was particularly associated with poorer learning about safety cues. Such relationships were not observed for blocking and conditioned inhibition. These results suggest that the relationship between anxiety and fear learning is complex and warrants further investigation of the potential mediating role of higher-order cognitive faculties.

Enhancing Inhibitory Learning: The Utility of Variability in Exposure

Exposure therapy has strong empirical support as a treatment for anxiety and related disorders, yet not all participants see clinically meaningful reduction in symptoms, and some experience return of fear. In this review, we examine the theoretical models of exposure therapy, from early precursors to the contemporary inhibitory learning model. The inhibitory learning model is applied to examine one potential method of improving outcomes in exposure therapy: increasing variability in the progression of the exposure hierarchy. We explore mechanisms that support the use of variability in exposure, including the violation of expectancies to enhance learning. In addition, the role of intolerance of uncertainty in anxiety is examined; variable exposure therapy could target this transdiagnostic mechanism in anxiety and related disorders. Suggestions for future research are then offered.

The uncertain brain: A co-ordinate based meta-analysis of the neural signatures supporting uncertainty during different contexts

Uncertainty is often inevitable in everyday life and can be both stressful and exciting. Given its relevance to psychopathology and wellbeing, recent research has begun to address the brain basis of uncertainty. In the current review we examined whether there are discrete and shared neural signatures for different uncertain contexts. From the literature we identified three broad categories of uncertainty currently empirically studied using functional MRI (fMRI): basic threat and reward uncertainty, decision-making under uncertainty, and associative learning under uncertainty. We examined the neural basis of each category by using a coordinate based meta-analysis, where brain activation foci from previously published fMRI experiments were drawn together (1998-2017; 87 studies). The analyses revealed shared and discrete patterns of neural activation for uncertainty, such as the insula and amygdala, depending on the category. Such findings will have relevance for researchers attempting to conceptualise uncertainty, as well as clinical researchers examining the neural basis of uncertainty in relation to psychopathology.

Fear extinction in the human brain: A meta-analysis of fMRI studies in healthy participants

The study of fear extinction represents an important example of translational neuroscience in psychiatry and promises to improve the understanding and treatment of anxiety and fear-related disorders. We present the results of a set of meta-analyses of human fear extinction studies in healthy participants, conducted with functional magnetic resonance imaging (fMRI) and reporting whole-brain results. Meta-analyses of fear extinction learning primarily implicate consistent activation of brain regions linked to threat appraisal and experience, including the dorsal anterior cingulate and anterior insular cortices. An overlapping anatomical result was obtained from the meta-analysis of extinction recall studies, except when studies directly compared an extinguished threat stimulus to an unextinguished threat stimulus (instead of a safety stimulus). In this latter instance, more consistent activation was observed in dorsolateral and ventromedial prefrontal cortex regions, together with other areas including the hippocampus. While our results partially support the notion of a shared neuroanatomy between human and rodent models of extinction processes, they also encourage an expanded account of the neural basis of human fear extinction.