Enhancing extinction learning: Occasional presentations of the unconditioned stimulus during extinction eliminate spontaneous recovery, but not necessarily reacquisition of fear

Signalling unpaired unconditional stimuli during extinction does not impair their effect to reduce renewal of conditional fear

Presenting unpaired unconditional stimuli (US) during extinction training reduces the renewal of conditional fear due to context change and slows re-acquisition. The present study investigated whether this reduced return of fear is mediated by Pavlovian inhibitory conditioning to the conditional stimulus paired with the US during acquisition (CS+) that is acquired when this stimulus is presented without the US in an excitatory extinction context. Using an ABA renewal paradigm that trained extinction in a context different from acquisition and renewal test, participants either received no USs (Standard), five unsignalled US presentations (Unsignalled) or five presentations of the US preceded by a novel, third CS (Signalled) during extinction training. Extinction was followed by tests for renewal and re-acquisition. Replicating previous results, renewal of electrodermal conditional responses was observed in group Standard, but not in group Unsignalled. Signalling the additional USs, and thus reducing context conditioning and the potential for inhibitory conditioning, did not reduce their effect in that renewal was absent in group Signalled. These results are inconsistent with an inhibitory conditioning account of the effects of unpaired US presentations during extinction. A trial sequence learning account or an arousal account may explain the effects of unpaired presentations of the US during extinction.

Quantification choices for individual differences: An example of mapping self-report to psychophysiological responses

A popular focus in affective neuroscience research has been to map the relationships between individual differences (e.g. personality and environmental experiences) and psychophysiological responses, in order to further understand the effect of individual differences upon neurobehavioral systems that support affect and arousal. Despite this trend, there have been a lack of practical examples demonstrating how the quantification of individual differences (e.g. categorical or continuous) impacts the observed relationships between different units of analysis (e.g. self-report > psychophysiological responses). To address this gap, we conducted a two-stage aggregated meta-analysis of self-reported intolerance of uncertainty (IU) and skin conductance responses during threat extinction (k = 18, n = 1006) using different quantification choices for individual differences in self-reported intolerance of uncertainty (continuous, categorical via median split, and categorical via extremes - one standard deviation above/below). Results from the meta-analyses revealed that the different quantification techniques produced some consistent (e.g. higher IU was significantly associated with skin conductance responding during late extinction training) and inconsistent IU-related effects. Furthermore, the number of statistically significant effects and effect sizes varied based on the quantification of individual differences in IU (e.g. categorical, compared to continuous was associated with more statistically significant effects, and larger effect sizes). The current study highlights how conducting different quantification methods for individual differences may help researchers understand the individual difference construct of interest (e.g. characterisation, measurement), as well as examine the stability and reliability of individual difference-based effects and correspondence between various units of analysis.

Reward processes in extinction learning and applications to exposure therapy

Anxiety disorders are common and highly distressing mental health conditions. Exposure therapy is a gold-standard treatment for anxiety disorders. Mechanisms of Pavlovian fear learning, and particularly fear extinction, are central to exposure therapy. A growing body of evidence suggests an important role of reward processes during Pavlovian fear extinction. Nonetheless, predominant models of exposure therapy do not currently incorporate reward processes. Herein, we present a theoretical model of reward processes in relation to Pavlovian mechanisms of exposure therapy, including a focus on dopaminergic prediction error signaling, coinciding positive emotional experiences (i.e., relief), and unexpected positive outcomes. We then highlight avenues for further research and discuss potential strategies to leverage reward processes to maximize exposure therapy response, such as pre-exposure interventions to increase reward sensitivity or post-exposure rehearsal (e.g., savoring, imaginal recounting strategies) to enhance retrieval and retention of learned associations.

Extinction of negative conditioned stimulus valence in human fear conditioning

Fear conditioning is a common experimental paradigm for modelling the development, and exposure-based treatment, of anxiety disorders. Measures of fear such as threat-expectancy, physiological arousal, and fear ratings typically extinguish, however feared stimuli may still be evaluated negatively (i.e. retain negative valence). This systematic review provides the first investigation of the relationship between fear conditioning methodology and extinction of negative stimulus valence. Principal findings were that type of CS (conditioned stimulus) and the CS-US pairing (i.e. specific combination of CS and unconditioned stimulus) predicted extinction outcome. Extinction of absolute negative CS valence was always achieved with shape CSs; often achieved with low fear-relevant animals as CSs, and less frequently achieved with faces as CSs - particularly neutral faces paired with a shock US. Modified extinction procedures typically achieved the same outcome as standard extinction procedures, except for partially-reinforced extinction, which was less effective than standard extinction, and positive imagery training, which was more effective than standard extinction. Further studies are warranted to evaluate the influence of fear conditioning methodology on extinction of absolute negative CS valence.

Evaluating the effects of counterconditioning, novelty-facilitated, and standard extinction on the spontaneous recovery of threat expectancy and conditioned stimulus valence

Extinction training has proved effective to diminish the expectancy of the aversive unconditioned stimulus (US). However, the negative valence of the conditioned stimulus (CS) may still stay intact. In fact, several studies have suggested that the CS negative valence may be a factor that promotes the return of fear. Our study focuses on the role of changes in the CS valence as a potential mechanism to reduce the spontaneous recovery of threat expectancies. To do that, we evaluated counterconditioning (CC), a technique aimed to reduce the CS negative valence by paring it with a positive stimulus and compared its efficacy to that of a novelty-facilitated extinction (NFE) and a standard extinction interventions. Using a 2-day protocol, participants first learned the relationship between a figure and an aversive sound, using a differential conditioning paradigm, and were then randomly assigned to one of three different groups. For the CC group, CS+ or cue A was paired with a positive US. The standard extinction group was exposed to cue A alone. For a third NFE group, cue A was followed by a neutral US. Finally, on the second day, spontaneous recovery was tested. Our findings did not provide evidence to suggest that CC could be more effective to prevent or reduce the return of threat expectancies or influence valence ratings when compared with NFE and standard extinction.

A model for recovery-from-extinction effects in Pavlovian conditioning and exposure therapy

Exposure therapy is an effective intervention for anxiety-related problems. The mechanism of this intervention has been the extinction procedure in Pavlovian conditioning, and this application has provided many successful instances for the prevention of relapse. However, traditional associative theories cannot comprehensively explain many findings. In particular, it is difficult to explain the recovery-from-extinction effects, which is the reappearance of the conditioned response following extinction. In this paper, we propose an associative model that is a mathematical extension of Bouton's (1993, Psychological Bulletin, 114, 80-99) model for the extinction procedure. The core of our model is that the asymptotic strength of the inhibitory association depends on the degree of excitatory association retrieved in a context in which a conditioned stimulus (CS) is presented and that the retrieval is determined by the similarity between contexts during both reinforcement and non-reinforcement and the retrieval context. Our model provides an explanation of the recovery-from-extinction effects, and implications for exposure therapy.

The influence of cross unconditional stimulus reinstatement on electrodermal responding and conditional stimulus valence in differential fear conditioning

We examined whether the inhibitory Conditional Stimulus (CS)-no Unconditional Stimulus (US) association formed during extinction can be triggered by a novel US during the reinstatement of conditional electrodermal responding and self-reported CS valence in human differential fear conditioning. Participants were trained with either a shock or an aversive scream US before undergoing extinction. Participants then received either the same (i.e., shock_shock or scream_scream) or a different US during reinstatement (i.e., shock_scream, scream_shock). Differential conditioning across all indices was stronger when a shock US was used during acquisition. After reinstatement, electrodermal responding to both the CS+ and the CS- increased regardless of the type of US used during reinstatement (non-differential reinstatement). Differential CS valence evaluations were larger after reinstatement in the groups that received the same US during acquisition and reinstatement (differential reinstatement), but differential evaluations did not increase in the groups receiving a different US at reinstatement. This dissociation suggests that the reinstatement of negative stimulus valence and the reinstatement of expectancy learning may differ.

The gold-standard treatment for social anxiety disorder: A roadmap for the future

Exposure therapy (ET), which follows the Pavlovian extinction model, is regarded as the gold-standard treatment for social anxiety disorder (SAD). The prospect of virtual reality in lieu of a traditional laboratory setting for the treatment of SAD has not been rigorously explored. The aim of the review was to summarize, find gaps in the current literature, and formulate future research direction by identifying two broad research questions: the comparative efficacy between in vivo ET and virtual reality exposure therapy (VRET) and the effectiveness of the Pavlovian extinction model in treating SAD. The criteria for effectiveness were effect size, relapse prevention, attrition rate and ecological validity. A literature search on recent randomized controlled trials yielded a total of 6 original studies (N=358), excluding duplication and overlapping participants. All studies supported that VRET was as effective as in vivo ET. Behavioral therapy that follows classical conditioning principles has a high attrition and relapse rate. Comparisons were drawn between the efficacy of the Pavlovian extinction model and other existing models, including third-wave approaches. The neural markers are suggested to be included as efficacy measures in treating SAD. The gold-standard treatment for SAD requires a paradigm shift through rigorous longitudinal comparative studies.

Effects of confronting the feared outcome during exposure therapy on the return of fear: An analogue study

BACKGROUND AND OBJECTIVES

Although exposure therapy is an efficacious treatment for anxiety disorders, fear often returns after treatment. From an inhibitory learning perspective, long-term improvement depends not only on learning that feared stimuli are safe, but also that it is safe to experience the emotional response triggered by these stimuli. Accordingly, the current study examined the effects of occasional threat reinforcement during repeated exposure to multiple cues on the return of fear in snake phobia by incorporating reminders of the feared outcome.

METHODS

Snake fearful community adults (N = 74) were randomized to either repeated exposure to multiple cues or exposure to multiple cues that also explicitly depicted the feared outcome (snake biting someone). A measure of self-reported threat expectancy and a threat-relevant behavioral approach task (BAT) were administered pre-exposure, post-exposure, and at a one-week follow-up.

RESULTS

Compared to the multiple-cue exposure group, the multiple-cue + fear-outcome group showed significantly less subjective expectancy for a snake to bite and increased behavioral approach of snake images at one-week follow-up. The fear-outcome group also reported significantly greater variability in distress during exposure than the multiple-cue exposure group and this difference mediated the intervention effect on behavioral approach at follow-up.

LIMITATIONS

Findings are limited by the use of videos as an analogue to exposure and a computer-delivered BAT.

CONCLUSIONS

These findings suggest presentation of the feared outcome may result in more variability in distress during exposure therapy and this may partially explain the maintenance of behavioral gains.

Limitations of occasional reinforced extinction to alleviate spontaneous recovery and reinstatement effects: Evidence for a trial-signalling mechanism

Fear extinction is not permanent but is instead more vulnerable than the original fear memory, as traditionally shown by the return of fear phenomena. Because of this, techniques to mitigate the return of fear are needed in the clinical treatment of related psychological conditions. One promising strategy is the occasional reinforced extinction treatment, introducing a gradual and sparse number of conditioned stimulus-unconditioned stimulus (CS-US) pairings within the extinction treatment. We present the results of three experiments in which we used a threat conditioning procedure in humans. Our main aim was to evaluate whether occasional reinforced extinction could reduce two different forms of relapse: spontaneous recovery (Experiments 1 and 2) and reinstatement (Experiment 3). Contrary to our predictions and previous literature, the results indicate that an occasional reinforcement treatment did not mitigate relapse compared with standard extinction. From a theoretical standpoint, these results are more consistent with the idea that extinction entails the acquisition of new knowledge than with the idea that there are conditions in which extinction leads to a weakening of the original fear memory. These findings also question the generality of the potential benefits of using occasional reinforced extinction in clinical settings.

Knowledge and competency standards for specialized cognitive behavior therapy for adult obsessive-compulsive disorder

Obsessive-Compulsive Disorder (OCD) is a leading cause of disability world-wide (World Health Organization, 2008). Treatment of OCD is a specialized field whose aim is recovery from illness for as many patients as possible. The evidence-based psychotherapeutic treatment for OCD is specialized cognitive behavior therapy (CBT, NICE, 2005, Koran and Simpson, 2013). However, these treatments are not accessible to many sufferers around the world. Currently available guidelines for care are deemed to be essential but insufficient because of highly variable clinician knowledge and competencies specific to OCD. The phase two mandate of the 14 nation International OCD Accreditation Task Force (ATF) created by the Canadian Institute for Obsessive Compulsive Disorders is development of knowledge and competency standards for specialized treatments for OCD through the lifespan deemed by experts to be foundational to transformative change in this field. This paper presents knowledge and competency standards for specialized CBT for adult OCD developed to inform, advance, and offer a model for clinical practice and training for OCD. During upcoming ATF phases three and four criteria and processes for training in specialized treatments for OCD through the lifespan for certification (individuals) and accreditation (sites) will be developed based on the ATF standards.

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.

Presentation of unpaired unconditional stimuli during extinction reduces renewal of conditional fear and slows re-acquisition

Past research has shown that presenting unconditional stimuli (US) during extinction training, either paired with the conditional stimulus (CS) or explicitly unpaired, can reduce spontaneous recovery and slow the re-acquisition of conditional fear. Whether contextual renewal of conditioned fear as indexed by electrodermal responses and self-report measures of anxiety and CS evaluations is also reduced after presentation of paired or unpaired USs during extinction training is currently unclear. Three groups of participants (Paired, Unpaired, Standard Extinction) completed a sequence of habituation, acquisition, extinction, renewal, and re-acquisition phases. During extinction, five CS-US pairings were presented in group Paired, whereas five US were presented alone in group Unpaired. No US were presented during standard extinction. For all groups, extinction was conducted in a context that was different from that of the other phases. Extinction of differential electrodermal responding was evident in groups Unpaired and Standard, but not in group Paired. Contextual renewal and fast re-acquisition, as indexed by differential electrodermal responding, were evident in group Standard, but not in group Unpaired and differential electrodermal responding persisted in group Paired. After extinction, self-reported anxiety was higher in groups Paired and Unpaired, but differential CS evaluations were evident in group Paired only. The current results suggest that presenting additional unpaired USs during extinction training strengthens extinction and protects against the renewal of differential electrodermal responding.

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.

Inactivation of the interpositus nucleus during unpaired extinction does not prevent extinction of conditioned eyeblink responses or conditioning-specific reflex modification

For almost 75 years, classical eyeblink conditioning has been an invaluable tool for assessing associative learning processes across many species, thanks to its high translatability and well-defined neural circuitry. Our laboratory has adapted the paradigm to extensively detail associative changes in the rabbit reflexive eyeblink response (unconditioned response, UR), characterized by postconditioning increases in the frequency, size, and latency of the UR when the periorbital shock unconditioned stimulus (US) is presented alone, termed conditioning-specific reflex modification (CRM). Because the shape and timing of CRM closely resembles the conditioned eyeblink response (CR) to the tone conditioned stimulus (CS), we previously tested whether CRs and CRM share a common neural substrate, the interpositus nucleus of the cerebellum (IP), and found that IP inactivation during conditioning blocked the development of both CRs and the timing aspect of CRM. The goal of the current study was to examine whether extinction of CRs and CRM timing, accomplished simultaneously with unpaired CS/US extinction, also involves the IP. Results showed that muscimol inactivation of the IP during extinction blocked CR expression but not extinction of CRs or CRM timing, contrasting with the literature showing IP inactivation prevents CR extinction during CS-alone presentations. The continued presence of the US throughout the unpaired extinction procedure may have been sufficient to overcome IP blockade, promoting plasticity in the cerebellar cortex and/or extracerebellar components of the eyeblink conditioning pathway that can modulate extinction of CRs and CRM timing. Results therefore add support to the distributed plasticity view of cerebellar learning. (PsycINFO Database Record (c) 2019 APA, all rights reserved).