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

Enhancing fear extinction

Gradually reducing a source of fear during extinction treatments may weaken negative memories in the long term.

The impact of extinction timing on pre-extinction arousal and subsequent return of fear

Exposure-based therapy is effective in treating anxiety, but a return of fear in the form of relapse is common. Exposure is based on the extinction of Pavlovian fear conditioning. Both animal and human studies point to increased arousal during immediate compared to delayed extinction (>+24 h), which presumably impairs extinction learning and increases the subsequent return of fear. Impaired extinction learning under arousal might interfere with psychotherapeutic interventions. The aim of the present study was to investigate whether arousal before extinction differs between extinction groups and whether arousal before extinction predicts the return of fear in a later (retention) test. As a highlight, both the time between fear acquisition and extinction (immediate vs. delayed) and the time between extinction and test (early vs. late test) were systematically varied. We performed follow-up analyses on data from 103 young, healthy participants to test the above hypotheses. Subjective arousal ratings and physiological arousal measures of sympathetic and hypothalamic pituitary adrenal axis activation (tonic skin conductance and salivary cortisol) were collected. Increased pre-extinction arousal in the immediate extinction group was only confirmed for subjective arousal. In linear regression analyses, none of the arousal measures predicted a significant return of fear in the different experimental groups. Only when we aggregated across the two test groups, tonic skin conductance at the onset of extinction predicted the return of fear in skin conductance responses. The overall results provide little evidence that pre-extinction arousal affects subsequent extinction learning and memory. In terms of clinical relevance, there is no clear evidence that exposure could be improved by reducing subjective or physiological arousal.

Fear Reduced Through Unconditional Stimulus Deflation Is Behaviorally Distinct From Extinction and Differentially Engages the Amygdala

Background

Context fear memory can be reliably reduced by subsequent pairings of that context with a weaker shock. This procedure shares similarities with extinction learning: both involve extended time in the conditioning chamber following training and reduce context-elicited fear. Unlike extinction, this weak-shock exposure has been hypothesized to engage reconsolidation-like processes that weaken the original memory.

Methods

We directly compared the weak-shock procedure with extinction using male and female Long Evans rats.

Results

Both repeated weak-shock exposure and extinction resulted in decreased context freezing relative to animals that received context fear conditioning but no subsequent context exposure. Conditioning with the weak shock was not enough to form a persistent context-shock association on its own, suggesting that the weak-shock procedure does not create a new memory. Weak-shock exposure in a new context can still reduce freezing elicited by the training context, suggesting that it reduces responding through a different process than extinction, which does not transcend context. Finally, reduced fear behavior produced through both extinction and weak-shock exposure was mirrored by reduced zif268 expression in the basolateral amygdala. However, only the weak-shock procedure resulted in changes in lysine-48 polyubiquitin tagging in the synapse of the basolateral amygdala, suggesting that this procedure produced long-lasting changes in synaptic function within the basolateral amygdala.

Conclusions

These results suggest that the weak-shock procedure does not rely on the creation of a new inhibitory memory, as in extinction, and instead may alter the original representation of the shock to reduce fear responding.

Genome-wide association study and the randomized controlled trial: A false equivalence

Madole & Harden's assertion that the effects derived from within-family genome-wide association studies (GWASs) and from randomized controlled trials (RCTs) are equivalent is misleading. GWASs are substantially more "non-unitary, non-uniform, and non-explanatory" than RCTs. While the within-family GWAS bring us closer to identifying genetic causes, whether it will change behavioral genetics into a causal science is an open question.

Memory retrieval, reconsolidation, and extinction: Exploring the boundary conditions of post-conditioning cue exposure

Following fear conditioning, behavior can be reduced by giving many CS-alone presentations in a process known as extinction or by presenting a few CS-alone presentations and interfering with subsequent memory reconsolidation. While the two share procedural similarities, both the behavioral outcomes and the neurobiological underpinnings are distinct. Here we review the neural and behavioral mechanisms that produce these separate behavioral reductions, as well as some factors that determine whether or not a retrieval-dependent reconsolidation process or an extinction process will be in effect.

Cautionary Observations Concerning the Introduction of Psychophysiological Biomarkers into Neuropsychiatric Practice

The combination of statistical learning technologies with large databases of psychophysiological data has appropriately generated enthusiastic interest in future clinical applicability. It is argued here that this enthusiasm should be tempered with the understanding that significant obstacles must be overcome before the systematic introduction of psychophysiological measures into neuropsychiatric practice becomes possible. The objective of this study is to identify challenges to this effort. The nonspecificity of psychophysiological measures complicates their use in diagnosis. Low test-retest reliability complicates use in longitudinal assessment, and quantitative psychophysiological measures can normalize in response to placebo intervention. Ten cautionary observations are introduced and, in some instances, possible directions for remediation are suggested.

A Randomized-Controlled Trial of EMDR Flash Technique on Traumatic Symptoms, Depression, Anxiety, Stress, and Life of Quality With Individuals Who Have Experienced a Traffic Accident

The Flash Technique of Eye Movement Desensitization and Reprocessing (EMDR) is widely recognized for its effectiveness in reducing the effects of emotional responses associated with traumatic memories. Using a randomized-controlled trial methodology, this study attempts to establish the efficacy of the EMDR Flash Technique. This study’s sample includes volunteers who were involved in traffic accidents and were given the randomized EMDR Flash Technique and Improving Mental Health Training for Primary Care Residents (mhGAP) Stress management module. The participants were given a socio-demographic data form, the Depression-Anxiety-Stress 21 scale (DASS-21), the Impact of Event Scale-Revised (IES-R), and the WHOQOL Quality of Life scale. Participants were evaluated using measurements taken before and after the application, as well as a one-month follow-up. The mean age of the participants was 36.20 (11.41) years and 82.1% (n = 32) were female. The DASS-21 Anxiety (η² = 0.085), IES-R Intrusion (η² = 0.101), Avoidance (η² = 0.124), Total (η² = 0.147), and WHOQOL-BREF Psychological (η² = 0.106) score improvements of the EMDR Flash Technique group were shown to be statistically significant when compared to the mhGAP group. However, no statistically significant difference in the DASS-21 Depression, Stress, Impact of Event Scale-Revised Hyperarousal WHOQOL-BREF General Health, Physical, Social Relationships, and Environment component scores was reported between the two groups. The present study’s findings clearly demonstrate that the EMDR Flash technique, when applied to persons involved in traffic accidents, is successful in improving anxiety, intrusion, avoidance, total traumatic stress, and mental quality of life symptoms for at least 1 month. We believe that these findings will improve the reliability and applicability of the EMDR Flash Technique, which was tested for the first time in a clinical randomized-controlled trial (RCT).