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

Updating Fearful Memories with Extinction Training during Reconsolidation: A Human Study Using Auditory Aversive Stimuli

Learning to fear danger in the environment is essential to survival, but dysregulation of the fear system is at the core of many anxiety disorders. As a consequence, a great interest has emerged in developing strategies for suppressing fear memories in maladaptive cases. Recent research has focused in the process of reconsolidation where memories become labile after being retrieved. In a behavioral manipulation, Schiller et al., (2010) reported that extinction training, administrated during memory reconsolidation, could erase fear responses. The implications of this study are crucial for the possible treatment of anxiety disorders without the administration of drugs. However, attempts to replicate this effect by other groups have been so far unsuccessful. We sought out to reproduce Schiller et al., (2010) findings in a different fear conditioning paradigm based on auditory aversive stimuli instead of electric shock. Following a within-subject design, participants were conditioned to two different sounds and skin conductance response (SCR) was recorded as a measure of fear. Our results demonstrated that only the conditioned stimulus that was reminded 10 minutes before extinction training did not reinstate a fear response after a reminder trial consisting of the presentation of the unconditioned stimuli. For the first time, we replicated Schiller et al., (2010) behavioral manipulation and extended it to an auditory fear conditioning paradigm

Updating Farful Memories with Extinction Training during Reconsolidation: A Human Study Using Auditory Aversive Stimuli

Learning to fear danger in the environment is essential to survival, but dysregulation of the fear system is at the core of many anxiety disorders. As a consequence, a great interest has emerged in developing strategies for suppressing fear memories in maladaptive cases. Recent research has focused in the process of reconsolidation where memories become labile after being retrieved. In a behavioral manipulation, Schiller et al., (2010) reported that extinction training, administrated during memory reconsolidation, could erase fear responses. The implications of this study are crucial for the possible treatment of anxiety disorders without the administration of drugs. However, attempts to replicate this effect by other groups have been so far unsuccessful. We sought out to reproduce Schiller et al., (2010) findings in a different fear conditioning paradigm based on auditory aversive stimuli instead of electric shock. Following a within-subject design, participants were conditioned to two different sounds and skin conductance response (SCR) was recorded as a measure of fear. Our results demonstrated that only the conditioned stimulus that was reminded 10 minutes before extinction training did not reinstate a fear response after a reminder trial consisting of the presentation of the unconditioned stimuli. For the first time, we replicated Schiller et al., (2010) behavioral manipulation and extended it to an auditory fear conditioning paradigm

Mean Skin Conductance Response per trials across days.

<p>Mean SCRs (reactivated CSa, not reactivated CSb and NS) in non-reinforced trials. CSa and CSb acquired fear conditioning on Acquisition on Day 1. Ten minutes after memory reactivation (of CSa and NS), SCR decreased during Extinction training. On Day 3, ten minutes after reinstatement, CSb recovered fear response in the first trials, whereas CSa maintained equivalent levels of SCR from Extinction to Re-extinction. Error bars represent standard errors.</p

Experimental Design and Timeline.

<p>CSa: conditioned stimulus a; CSb: conditioned stimulus b; NS: neutral stimulus;</p><p>USa: unconditioned stimulus a (sound); USb: unconditioned stimulus b (sound).</p><p>On day 1 participants were first habituated to stimuli, immediately afterwards Acquisiton started. On day 2, participants reactivated memory of CSa and NS by one single presentation. After ten minutes, participants underwent extinction training. On day 3, participants were exposed to the aversive sounds. After ten minutes participants underwent Re-Extinction.</p

Mean Skin Conductance Response for Acquisition Extinction and Re-Extinction phases.

<p>Mean SCRs (reactivated CSa, not reactivated CSb and NS) during Acquisition (mean of the three final trials), Extinction (last trial) and Re-Extinction (first trial). CSs were equally fear conditioned and extinguished. After reinstatement, only CSb showed a significant increment of SCR in Re-Extinction. In contrast, CSa and NS maintained same levels of SCR between Extinction and Re-Extinction. CSa presented a significant reduction of SCR from Acquisition to Re-Extinction. *<i>p</i><.05. Error bars represent standard errors.</p

Comparative Experimental Designs of Schiller et al., (2010), current experiment and Kindt et al., (2011).

<p>Note that our current design (B) uses a different aversive stimulus modality (sounds instead of electric shocks). It uses a within-subject design and includes a habituation phase for all stimuli. Note that design C (Kind et al., 2011) uses additional measures of fear such as: fear potentiated startle responses and online ratings of US expectancy (in every experimental phase). Design C also uses higher percentage of CS-US pairing, fear relevant pictures instead of colour squares and includes three tests of fear recovery on Day 3 (reinstatement, spontaneous recovery and re-acquisition, last one not shown in the figure). Note also that design C inserts startle probes during CS and NS presentations and during intertrial interval in every experimental phase.</p

Overestimating the intensity of negative feelings in autobiographical memory: Evidence from the 9/11 attack and COVID-19 pandemic

When recalling autobiographical events, people not only retrieve event details but also the feelings they experienced. The current study examined whether people are able to consistently recall the intensity of past feelings associated with two consequential and negatively valenced events, i.e. the 9/11 attack (N = 769) and the COVID-19 pandemic (N = 726). By comparing experienced and recalled intensities of negative feelings, we discovered that people systematically recall a higher intensity of negative feelings than initially reported – overestimating the intensity of past negative emotional experiences. The COVID-19 dataset also revealed that individuals who experienced greater improvement in emotional well- being displayed smaller biases in recalling their feelings. Across both datasets, the intensity of remembered feelings was correlated with initial feelings and current feelings, but the impact of the current feelings was stronger in the COVID-19 dataset than in the 9/11 dataset. Our results demonstrate that when recalling negative autobiographical events, people tend to overestimate the intensity of prior negative emotional experiences with their degree of bias influenced by current feelings and well-being