Less is more: Neural activity during very brief and clearly visible exposure to phobic stimuli

A double-blind trial of decoded neurofeedback intervention for specific phobias

AIM

A new closed-loop functional magnetic resonance imaging method called multivoxel neuroreinforcement has the potential to alleviate the subjective aversiveness of exposure-based interventions by directly inducing phobic representations in the brain, outside of conscious awareness. The current study seeks to test this method as an intervention for specific phobia.

METHODS

In a randomized, double-blind, controlled single-university trial, individuals diagnosed with at least two (one target, one control) animal subtype-specific phobias were randomly assigned (1:1:1) to receive one, three, or five sessions of multivoxel neuroreinforcement in which they were rewarded for implicit activation of a target animal representation. Amygdala response to phobic stimuli was assessed by study staff blind to target and control animal assignments. Pretreatment to posttreatment differences were analyzed with a two-way repeated-measures anova.

RESULTS

A total of 23 participants (69.6% female) were randomized to receive one (n = 8), three (n = 7), or five (n = 7) sessions of multivoxel neuroreinforcement. Eighteen (n = 6 each group) participants were analyzed for our primary outcome. After neuroreinforcement, we observed an interaction indicating a significant decrease in amygdala response for the target phobia but not the control phobia. No adverse events or dropouts were reported as a result of the intervention.

CONCLUSION

Results suggest that multivoxel neuroreinforcement can specifically reduce threat signatures in specific phobia. Consequently, this intervention may complement conventional psychotherapy approaches with a nondistressing experience for patients seeking treatment. This trial sets the stage for a larger randomized clinical trial to replicate these results and examine the effects on real-life exposure.

CLINICAL TRIAL REGISTRATION

The now-closed trial was prospectively registered at ClinicalTrials.gov with ID NCT03655262.

Advancing the treatment of anxiety disorders in transition-age youth: a review of the therapeutic effects of unconscious exposure

BACKGROUND

The real-world effectiveness of exposure-based therapies for youth depends on the willingness and ability of young people to tolerate confronting their fears, which can be experienced as highly aversive and create problems with treatment engagement and acceptance. Recently, neuroscientific research on the nonconscious basis of fear has been translated into novel exposure interventions that bypass conscious processing of feared stimuli and that thus do not cause phobic youth to experience distress. We present a review of these unconscious exposure interventions.

METHODS

A PRISMA-based search yielded 20 controlled experiments based on three paradigms that tested if fear-related responses could be reduced without conscious awareness in highly phobic, transition-age youth: 14 randomized controlled trials (RCTs), 5 fMRI studies (1 was also an RCT), 4 psychophysiological studies (3 were also RCTs), and 1 ERP study. We conducted meta-analyses of outcomes where feasible.

RESULTS

Unconscious exposure interventions significantly (1) reduced avoidance behavior (range of Cohen's d = 0.51-0.95) and self-reported fear (d = 0.45-1.25) during in vivo exposure to the feared situation; (2) reduced neurobiological indicators of fear (d = 0.54-0.62) and concomitant physiological arousal (d = 0.55-0.64); (3) activated neural systems supporting fear regulation more strongly than visible exposure to the same stimuli (d = 1.2-1.5); (4) activated regions supporting fear regulation that mediated the reduction of avoidance behavior (d = 0.70); (5) evoked ERPs suggesting encoding of extinction memories (d = 2.13); and (6) had these effects without inducing autonomic arousal or subjective fear.

CONCLUSIONS

Unconscious exposure interventions significantly reduce a variety of symptomatic behaviors with mostly moderate effect sizes in transition-age youth with specific phobias. fMRI and physiological findings establish a neurophysiological basis for this efficacy, and suggest it occurs through extinction learning. Unconscious exposure was well tolerated, entirely unassociated with drop out, and is highly scalable for clinical practice. However, a number of limitations must be addressed to assess potential clinical impacts, including combining unconscious exposure with exposure therapy to boost treatment acceptance and efficacy.

A double-blind trial of decoded neurofeedback intervention for specific phobias

Aim

A new closed-loop fMRI method called multi-voxel neuro-reinforcement has the potential to alleviate the subjective aversiveness of exposure-based interventions by directly inducing phobic representations in the brain, outside of conscious awareness. The current study seeks to test this method as an intervention for specific phobia.

Methods

In a randomized, double-blind, controlled single-university trial, individuals diagnosed with at least two (1 target, 1 control) animal subtype specific phobias were randomly assigned (1:1:1) to receive 1, 3, or 5 sessions of multi-voxel neuro-reinforcement in which they were rewarded for implicit activation of a target animal representation. Amygdala response to phobic stimuli was assessed by study staff blind to target and control animal assignments. Pre-treatment to post-treatment differences were analyzed with a 2-way repeated-measures ANOVA.

Results

A total of 23 participants (69.6% female) were randomized to receive 1 (n=8), 3 (n=7), or 5 (n=7) sessions of multi-voxel neuro-reinforcement. Eighteen (n=6 each group) participants were analyzed for our primary outcome. After neuro-reinforcement, we observed an interaction indicating a significant decrease in amygdala response for the target phobia but not the control phobia. No adverse events or dropouts were reported as a result of the intervention.

Conclusion

Results suggest multi-voxel neuro-reinforcement can specifically reduce threat signatures in specific phobia. Consequently, this intervention may complement conventional psychotherapy approaches with a non-distressing experience for patients seeking treatment. This trial sets the stage for a larger randomized clinical trial to replicate these results and examine the effects on real-life exposure.

Clinical Trial Registration

The now-closed trial was prospectively registered at ClinicalTrials.gov with ID NCT03655262.

Preliminary evidence for the acceptability, safety, and efficacy of the flash technique

Objectives

This study reports on four similar studies intended to explore the acceptability, safety, and efficacy of the flash technique (FT), a method of rapidly reducing the intensity of a disturbing memory or image, with minimal subjective disturbance for subjects during the process. Of the four studies, two were conducted during FT trainings in the United States, one in Australia, and one in Uganda.

Methods

The studies involve pre-, post-, and follow-up repeated-measures design to determine the effectiveness of a 15-min FT intervention. A total of 654 subjects were asked to think of a disturbing memory and then participate in a structured experience of an FT. The purpose of this investigation was to determine whether a brief application of an FT would be safe and effective in significantly reducing their disturbance. In each study, subjects rated their disturbing memories on a 0-to-10 scale, with zero representing no disturbance at all and 10 representing the worst they could imagine. Then, they took part in a 15-min group practicum where they were guided in a self-administering FT with no individual supervision or support.

Results

In all four studies, the mean reduction in disturbance exceeded two-thirds, the results were significant (p < 0.001), and the effect size was very large. Of the 813 sessions (654 subjects) represented in these studies, only two subjects reported slight increases in disturbances, and both of these subjects reported reductions in disturbance in their second FT experiences 2 h later. At a 4-week follow-up, mean disturbance levels in all four studies indicated maintenance of benefit or slightly further reduction of mean disturbance levels. An 18-month follow-up study with a subgroup of subjects who initially reported a high level of memory-related distress found similar maintenance of gains as well as symptom reduction.

Conclusion

These findings provide preliminary evidence of acceptability, safety, and efficacy of FT; therefore, further study is warranted.

The effectiveness, efficiency, and acceptability of EMDR vs. EMDR 2.0 vs. the Flash technique in the treatment of patients with PTSD: study protocol for the ENHANCE randomized controlled trial

Background

Several widely studied therapies have proven to be effective in the treatment of post-traumatic stress disorder (PTSD). However, there is still room for improvement because not all patients benefit from trauma-focused treatments. Improvements in the treatment of PTSD can be achieved by investigating ways to enhance existing therapies, such as eye movement desensitization and reprocessing (EMDR) therapy, as well as exploring novel treatments. The purpose of the current study is to determine the differential effectiveness, efficiency, and acceptability of EMDR therapy, an adaptation of EMDR therapy, referred to as EMDR 2.0, and a novel intervention for PTSD, the so-called Flash technique. The second aim is to identify the moderators of effectiveness for these interventions. This study will be conducted among individuals diagnosed with PTSD using a randomized controlled trial design.

Methods

A total of 130 patients diagnosed with (complex) PTSD will be randomly allocated to either six sessions of EMDR therapy, EMDR 2.0, or the Flash technique. The primary outcomes used to determine treatment effectiveness include the presence of a PTSD diagnosis and the severity of PTSD symptoms. The secondary outcomes of effectiveness include symptoms of depression, symptoms of dissociation, general psychiatric symptoms, and experiential avoidance. All patients will be assessed at baseline, at 4-week post-treatment, and at 12-week follow-up. Questionnaires indexing symptoms of PTSD, depression, general psychopathology, and experiential avoidance will also be assessed weekly during treatment and bi-weekly after treatment, until the 12-week follow-up. Efficiency will be assessed by investigating the time it takes both to lose the diagnostic status of PTSD, and to achieve reliable change in PTSD symptoms. Treatment acceptability will be assessed after the first treatment session and after treatment termination.

Discussion

This study is the first to investigate EMDR 2.0 therapy and the Flash technique in a sample of participants officially diagnosed with PTSD using a randomized controlled trial design. This study is expected to improve the available treatment options for PTSD and provide therapists with alternative ways to choose a therapy beyond its effectiveness by considering moderators, efficiency, and acceptability.

Trial registration

The trial was retrospectively registered in the ISRCTN registry at 10th November 2022 under registration number ISRCTN13100019.

The role of consciousness in threat extinction learning

Extinction learning is regarded as a core mechanism underlying exposure therapy. The extent to which learned threats can be extinguished without conscious awareness is a controversial and on-going debate. We investigated whether implicit vs. explicit exposure to a threatened stimulus can modulate defence responses measured using pupillometry. Healthy participants underwent a threat conditioning paradigm in which one of the conditioned stimuli (CS) was perceptually suppressed using continuous flash suppression (CFS). Participants' pupillary responses, CS pleasantness ratings, and trial-by-trial awareness of the CS were recorded. During Extinction, participants' pupils dilated more in the trials in which they were unaware of the CS than in those in which they were aware of it (Cohen's d = 0.57). After reinstatement, the percentage of fear recovery was greater for the CFS-suppressed CS than the CS with full awareness. The current study suggests that the modulation of fear responses by extinction with reduced visual awareness is weaker compared to extinction with full perceptual awareness.

Using expectation violation models to improve the outcome of psychological treatments

Expectations are a central maintaining mechanism in mental disorders and most psychological treatments aim to directly or indirectly modify clinically relevant expectations. Therefore, it is crucial to examine why patients with mental disorders maintain dysfunctional expectations, even in light of disconfirming evidence, and how expectation-violating situations should be created in treatment settings to optimize treatment outcome and reduce the risk of treatment failures. The different psychological subdisciplines offer various approaches for understanding the underlying mechanisms of expectation development, persistence, and change. Here, we convey recommendations on how to improve psychological treatments by considering these different perspectives. Based on our expectation violation model, we argue that the outcome of expectation violation depends on several characteristics: features of the expectation-violating situation; the dynamics between the magnitude of expectation violation and cognitive immunization processes; dealing with uncertainties during and after expectation change; controlled and automatic attention processes; and the costs of expectation changes. Personality factors further add to predict outcomes and may offer a basis for personalized treatment planning. We conclude with a list of recommendations derived from basic psychology that could contribute to improved treatment outcome and to reduced risks of treatment failures.

Neuronal Activity during Exposure to Specific Phobia through fMRI: Comparing Therapeutic Components of Cognitive Behavioral Therapy

Cognitive behavioral therapy (CBT) packages for anxiety disorders, such as phobias, usually include gradual exposure to anxious contexts, positive self-verbalizations, and relaxation breathing. The objective of this research was to analyze the specific neural activation produced by the self-verbalizations (S) and breathing (B) included in CBT. Thirty participants with clinical levels of a specific phobia to small animals were randomly assigned to three fMRI conditions in which individuals were exposed to phobic stimuli in real images: a group underwent S as a technique to reduce anxiety; a second group underwent B; and a control group underwent exposure only (E). Simple effects showed higher brain activation comparing E > S, E > B, and S > B. In particular, in the E group, compared to the experimental conditions, an activation was observed in sensory-perceptive and prefrontal and in other regions involved in the triggering of emotion (i.e., amygdala, supplementary motor area, and cingulate gyrus) as well as an activation associated with interoceptive sensitivity (i.e., insula and cingulate cortex). According to the specific tool used, discrepancies in the neural changes of CBT efficacy were observed. We discuss the theoretical implications according to the dual model of CBT as a set of therapeutic tools that activate different processes.

Nothing to Fear but Fear Itself: A Mechanistic Test of Unconscious Exposure

BACKGROUND

While effective, exposure therapy can be distressing, which creates problems with treatment acceptance. Can exposure be effectively delivered unconsciously-and thus without causing phobic people to experience distress? No study has tested this hypothesis in a sufficiently rigorous experiment that selected between mechanisms for reducing fear unconsciously.

METHODS

We conducted a psychophysiological experiment of an unconscious exposure intervention to discern its mechanism of therapeutic action. We identified 98 highly spider-phobic participants with a validated fear questionnaire and a Behavioral Avoidance Test in which they gradually approached and exhibited impairment of a live tarantula, which was indicative of a DSM-5 diagnosis of specific phobia. These participants were randomized to viewing unconscious exposure to spiders, visible exposure to spiders, or unconscious exposure to flowers (control). In a novel psychophysiological design, concurrent changes in sympathetic arousal and subjective fear were monitored throughout exposure. Shortly thereafter, phobic participants approached the tarantula again in order to measure exposure-induced changes in real-life avoidance behavior and experienced fear.

RESULTS

Unconscious exposure did not induce concurrent changes in sympathetic arousal or subjective fear, and subsequently reduced fear of the tarantula. Visible exposure to the same phobic stimuli, by contrast, induced significant arousal and fear, but did not affect fear of the tarantula. Levels of arousal during exposure moderated effects on fear of the tarantula: lower arousal during unconscious exposure, but not during conscious exposure, predicted greater fear reduction.

CONCLUSIONS

Unconscious exposure reduces fear by generating new implicit learning of nonaversive, stimulus-response associations that facilitate fear extinction in phobic persons.

Neural processing of emotional facial stimuli in specific phobia: An fMRI study

BACKGROUND

Patients with specific phobia (SP) show altered brain activation when confronted with phobia-specific stimuli. It is unclear whether this pathogenic activation pattern generalizes to other emotional stimuli. This study addresses this question by employing a well-powered sample while implementing an established paradigm using nonspecific aversive facial stimuli.

METHODS

N = 111 patients with SP, spider subtype, and N = 111 healthy controls (HCs) performed a supraliminal emotional face-matching paradigm contrasting aversive faces versus shapes in a 3-T magnetic resonance imaging scanner. We performed region of interest (ROI) analyses for the amygdala, the insula, and the anterior cingulate cortex using univariate as well as machine-learning-based multivariate statistics based on this data. Additionally, we investigated functional connectivity by means of psychophysiological interaction (PPI).

RESULTS

Although the presentation of emotional faces showed significant activation in all three ROIs across both groups, no group differences emerged in all ROIs. Across both groups and in the HC > SP contrast, PPI analyses showed significant task-related connectivity of brain areas typically linked to higher-order emotion processing with the amygdala. The machine learning approach based on whole-brain activity patterns could significantly differentiate the groups with 73% balanced accuracy.

CONCLUSIONS

Patients suffering from SP are characterized by differences in the connectivity of the amygdala and areas typically linked to emotional processing in response to aversive facial stimuli (inferior parietal cortex, fusiform gyrus, middle cingulate, postcentral cortex, and insula). This might implicate a subtle difference in the processing of nonspecific emotional stimuli and warrants more research furthering our understanding of neurofunctional alteration in patients with SP.

A Model for the Flash Technique Based on Working Memory and Neuroscience Research

Research has shown that the Flash Technique (FT) appears to reduce memory-related disturbance and may reduce symptoms of posttraumatic stress disorder. This paper discusses the connections between FT and eye movement desensitization and reprocessing (EMDR) therapy. In FT, clients remind themselves of a traumatic memory without dwelling on it and focus instead on a positive engaging focus and then blink their eyes when prompted. This paper summarizes numerous models describing how the brain processes traumatic material and presents a model for how FT may work in the brain. It proposes that during the blinking, the patient's periaqueductal gray (PAG) may take over, sensing the reminder of the traumatic memory and reflexively triggering the amygdala. In Porges's neuroception model, the PAG assesses danger without going through the conscious brain. Recent fMRI data show that for patients with posttraumatic stress disorder, there is enhanced connectivity from the amygdala to the left hippocampus. Thus, triggering the amygdala may, in turn, activate the left hippocampus, which may then provide a brief access to the traumatic memory. Given the brief access, there is insufficient time for the amygdala to go into overactivation. The client remains calm while accessing the traumatic memory, thus setting up the prediction error necessary for possible memory reconsolidation. This process is repeated during blinking in FT allowing memory reconsolidation to proceed. This model requires experimental confirmation.

A Sequential Multiple Assignment Randomized Trial (SMART) study of medication and CBT sequencing in the treatment of pediatric anxiety disorders

BACKGROUND

Treatment of a child who has an anxiety disorder usually begins with the question of which treatment to start first, medication or psychotherapy. Both have strong empirical support, but few studies have compared their effectiveness head-to-head, and none has investigated what to do if the treatment tried first isn't working well-whether to optimize the treatment already begun or to add the other treatment.

METHODS

This is a single-blind Sequential Multiple Assignment Randomized Trial (SMART) of 24 weeks duration with two levels of randomization, one in each of two 12-week stages. In Stage 1, children will be randomized to fluoxetine or Coping Cat Cognitive Behavioral Therapy (CBT). In Stage 2, remitters will continue maintenance-level therapy with the single-modality treatment received in Stage 1. Non-remitters during the first 12 weeks of treatment will be randomized to either [1] optimization of their Stage 1 treatment, or [2] optimization of Stage 1 treatment and addition of the other intervention. After the 24-week trial, we will follow participants during open, naturalistic treatment to assess the durability of study treatment effects. Patients, 8-17 years of age who are diagnosed with an anxiety disorder, will be recruited and treated within 9 large clinical sites throughout greater Los Angeles. They will be predominantly underserved, ethnic minorities. The primary outcome measure will be the self-report score on the 41-item youth SCARED (Screen for Child Anxiety Related Disorders). An intent-to-treat analysis will compare youth randomized to fluoxetine first versus those randomized to CBT first ("Main Effect 1"). Then, among Stage 1 non-remitters, we will compare non-remitters randomized to optimization of their Stage 1 monotherapy versus non-remitters randomized to combination treatment ("Main Effect 2"). The interaction of these main effects will assess whether one of the 4 treatment sequences (CBT➔CBT; CBT➔med; med➔med; med➔CBT) in non-remitters is significantly better or worse than predicted from main effects alone.

DISCUSSION

Findings from this SMART study will identify treatment sequences that optimize outcomes in ethnically diverse pediatric patients from underserved low- and middle-income households who have anxiety disorders.

TRIAL REGISTRATION

This protocol, version 1.0, was registered in ClinicalTrials.gov on February 17, 2021 with Identifier: NCT04760275 .

Systematic Review of Studies on Subliminal Exposure to Phobic Stimuli: Integrating Therapeutic Models for Specific Phobias

We systematically review 26 papers investigating subjective, behavioral, and psychophysiological correlates of subliminal exposure to phobic stimuli in phobic patients. Stimulations were found to elicit: (1) cardiac defense responses, (2) specific brain activations of both subcortical (e.g., amygdala) and cortical structures, (3) skin conductance reactions, only when stimuli lasted >20 ms and were administered with intertrial interval >20 s. While not inducing the distress caused by current (supraliminal) exposure therapies, exposure to subliminal phobic stimuli still results in successful extinction of both psychophysiological and behavioral correlates: however, it hardly improves subjective fear. We integrate those results with recent bifactorial models of emotional regulation, proposing a new form of exposure therapy whose effectiveness and acceptability should be maximized by a preliminary subliminal stimulation. Systematic Review Registration: identifier [CRD42021129234].

Conscious and unconscious brain responses to food and cocaine cues

Visual presentation of appetitive and negative cues triggers fast responses in the human brain. Here we assessed functional MRI (fMRI) responses to food, cocaine, and neutral cues presented at a subliminal ("unconscious", 33 ms) and supraliminal ("conscious", 750 and 3000 ms) level in healthy, cocaine naïve volunteers. Because there is evidence of circadian variability in reward sensitivity, our second aim was to assess diurnal variability in the brain's reactivity to cues. Sixteen participants completed two randomly ordered fMRI sessions (once 9-11 AM and another 5-7 PM). in which food, cocaine, and neutral cues were presented for 33, 750 and 3000 ms. Participants rated food cues as positive and "wanted" (more so in evenings than mornings), and cocaine cues as negative (no diurnal differences). fMRI showed occipital cortex activation for food>neutral, cocaine>neutral and cocaine>food; dorsolateral prefrontal cortex for cocaine>neutral and cocaine>food, and midbrain for cocaine>food (all p_FWE < 0.05). When comparing unconscious (33 ms) > conscious (750 and 3000 ms) presentations, we observed significant differences for cocaine>neutral and cocaine>food in occipital cortex, for cocaine>neutral in the insula/temporal lobe, and for food>neutral in the middle temporal gyrus (p_FWE < 0.05). No diurnal differences for brain activations were observed. We interpret these findings to suggest that negative items (e.g., cocaine) might be perceived at a faster speed than positive ones (e.g., food), although we cannot rule out that the higher saliency of cocaine cues, which would be novel to non-drug using individuals, contributed to the faster speed of detection.

Flash Technique in a Scalable Low-Intensity Group Intervention for COVID-19-Related Stress in Healthcare Providers

The flash technique (FT) is a low-intensity individual or group intervention that appears to rapidly lessen the distress of disturbing and traumatic memories. This paper reports on the safety and effectiveness of group FT with 77 healthcare providers and 98 psychotherapists impacted by working with COVID-19 patients. One-hour webinars included 30 minutes of psychoeducation and two guided 15-minute FT interventions, focused on participants' most distressing pandemic-related memory. Before and after each 15-minute FT intervention, they rated that memory using the 11-point 0-to-10 subjective units of disturbance (SUD) scale. Results from both interventions were highly significant with large effect sizes (p < .001, Hedges' g = 2.01, Hedges' g = 2.39). No adverse reactions were reported. For 35 participants who processed the same memory in both interventions, the pre–post SUD scores from the beginning of intervention #1 to the end of intervention #2 showed a significant reduction with a large effect size (p < .001, Hedges' g = 3.80). For this group, both intervention #1 and intervention #2 showed significant reductions with large effect sizes (p < .001, Hedges' g = 2.00) (p < .001, Hedges' g = 1.18). Follow-up SUD scores were obtained from 58 participants, with the mean disturbance level showing a significant further decrease. These findings provide preliminary evidence that group FT appears to safely provide rapid relief from disturbing memories. FT merits further research.

Spider Phobia: Neural Networks Informing Diagnosis and (Virtual/Augmented Reality-Based) Cognitive Behavioral Psychotherapy-A Narrative Review

Recent fMRI studies on specific animal phobias, particularly spider phobia (arachnophobia), have identified a large variety of specific brain regions involved in normal and disturbed fear processing. Both functional and structural brain abnormalities have been identified among phobic patients. Current research suggests that both conscious and subconscious fear processing play a crucial role in phobic disorders. Cognitive behavioral therapy has been identified as an effective treatment for specific phobias and has been associated with neuroplastic effects which can be evaluated using current neuroimaging techniques. Recent research suggests that new approaches using virtual (VR) or augmented reality (AR) tend to be similarly effective as traditional "in vivo" therapy methods and could expand treatment options for different medical or individual scenarios. This narrative review elaborates on neural structures and particularities of arachnophobia. Current treatment options are discussed and future research questions are highlighted.

Brain-based mediation of non-conscious reduction of phobic avoidance in young women during functional MRI: a randomised controlled experiment

BACKGROUND

Exposure therapy is the treatment of choice for anxiety disorders but requires people to confront feared situations and can be distressing. We tested the hypothesis that exposure without conscious awareness would reduce fear in participants with specific phobia by harnessing the neural circuitry supporting the automatic extinction of fear.

METHODS

In this single-centre, randomised controlled experiment, we recruited women aged 18-29 years from an ethnically diverse, community-based population in northeastern USA, between Sept 1, 2013, and Aug 1, 2016. Eligible participants classified as having phobia met the DSM-5 criteria for specific phobia but not for any other disorder, had scores in the top 10% of respondents to the Fear of Spiders Questionnaire, and exhibited impairing avoidance of a live tarantula. Eligible controls met no criteria for any disorder, were in the bottom 30% of questionnaire respondents, and displayed no avoidance of the tarantula. The randomisation schedule was generated with the open source Research Randomizer Tool. A research assistant randomly assigned participants to the active intervention of very brief exposure (VBE)-the repeated presentation of masked phobic stimuli (ie, spiders)-or the control intervention which used masked flowers (VBF). VBE and VBF were given code numbers to prevent staff from knowing which intervention they were administering. During a 10 min functional MRI (fMRI) task, each participant was exposed to 16 blocks of ten masked target stimuli (spiders or flowers), alternating with 16 blocks of ten masked neutral stimuli. A few minutes after fMRI, participants with spider phobia approached the tarantula again so we could measure changes in phobic behaviour. The primary outcome was real-time changes in brain activity measured by fMRI. All analyses were done by intention to treat.

RESULTS

We recruited 82 women, of whom 42 had spider phobia and 40 were controls. VBE generated stronger neural activity in participants with spider phobia than in controls, particularly in regions supporting emotion, emotion regulation, and attention systems, such as the inferior frontal cortex (Cohen's d 0·95, 95% CI 0·93-0·98, Bayesian posterior probability 99·5%) and the caudate nucleus (1·16, 1·14-1·18, 100·0%). In participants with phobia, VBE also generated stronger activity in these regions than did VBF (eg, dorsal anterior cingulate cortex Cohen's d 0·80, 95% CI 0·78-0·80, Bayesian posterior probability 98·5%; caudate nucleus 1·0, 0·98-1·02, 99·5%). VBE reduced avoidance of the live tarantula in participants with phobia. Regions supporting fear extinction (including ventral medial prefrontal cortex) and emotional salience processing mediated this effect. No adverse events occurred.

INTERPRETATION

VBE reduced fear non-consciously in participants with spider phobia by recruiting brain regions supporting automatic fear extinction, emotion regulation, and top-down attentional processing. Future studies should explore the use of VBE in other fear-based disorders.

FUNDING

National Institutes of Mental Health and Brain & Behavior Research Foundation.

Recent developments in the intervention of specific phobia among adults: a rapid review

Specific phobia is highly prevalent worldwide. Although the body of intervention studies is expanding, there is a lack of reviews that summarise recent progress and discuss the challenges and direction of research in this area. Hence, this rapid review seeks to systematically evaluate the available evidence in the last five years in the treatment of specific phobias in adults. Studies published between January 2014 to December 2019 were identified through searches on the electronic databases of Medline and PsychINFO. In total, 33 studies were included. Evidence indicates that psychotherapy, and in particular cognitive behaviour therapy, when implemented independently or as an adjunctive, is a superior intervention with large effect sizes. Technology-assisted therapies seem to have a beneficial effect on alleviating fears and are described to be more tolerable than in vivo exposure therapy. Pharmacological agents are investigated solely as adjuncts to exposure therapy, but the effects are inconsistent; propranolol and glucocorticoid may be promising. A handful of cognitive-based therapies designed to alter fear arousal and activation pathways of phobias have presented preliminary, positive outcomes. Challenges remain with the inherent heterogeneity of specific phobia as a disorder and the accompanying variability in outcome measures and intervention approaches to warrant a clear conclusion on efficacy.

Implicit but not explicit extinction to threat-conditioned stimulus prevents spontaneous recovery of threat-potentiated startle responses in humans

INTRODUCTION

It has long been posited that threat learning operates and forms under an affective and a cognitive learning system that is supported by different brain circuits. A primary drawback in exposure-based therapies is the high rate of relapse that occurs when higher order areas fail to inhibit responses driven by the defensive circuit. It has been shown that implicit exposure of fearful stimuli leads to a long-lasting reduction in avoidance behavior in patients with phobia. Despite the potential benefits of this approach in the treatment of phobias and posttraumatic stress disorder, implicit extinction is still underinvestigated.

METHODS

Two groups of healthy participants were threat conditioned. The following day, extinction training was conducted using a stereoscope. One group of participants was explicitly exposed with the threat-conditioned image, while the other group was implicitly exposed using a continuous flash suppression (CFS) technique. On the third day, we tested the spontaneous recovery of defensive responses using explicit presentations of the images.

RESULTS

On the third day, we found that only the implicit extinction group showed reduced spontaneous recovery of defensive responses to the threat-conditioned stimulus, measured by threat-potentiated startle responses but not by the electrodermal activity.

CONCLUSION

Our results suggest that implicit extinction using CFS might facilitate the modulation of the affective component of fearful memories, attenuating its expression after 24 hr. The limitations of the CFS technique using threatful stimuli urge the development of new strategies to improve implicit presentations and circumvent such limitations. Our study encourages further investigations of implicit extinction as a potential therapeutic target to further advance exposure-based psychotherapies.

Unconscious Psychological Treatments for Physiological Survival Circuits

The idea of targeting unconscious or implicit processes in psychological treatments is not new, but until recently it has not been easy to manipulate these processes without also engaging consciousness. Here we review how this is possible, using various modern cognitive neuroscience methods including a technique known as Decoded Neural-Reinforcement. We discuss the general advantages of this approach, such as how it can facilitate double-blind placebo-controlled studies, and minimize premature patient dropouts in the treatment of fear. We also speculate how this may generalize to other similar physiological survival processes.