Tackling fear: Beyond associative memory activation as the only determinant of fear responding

Underlying Working Mechanisms of Virtual Reality Exposure: Exploring the Role of Fearful Expectancies and Habituation

While research has primarily focused on establishing the efficacy of virtual reality (VR) exposure, relatively scant attention has been paid to the underlying working mechanisms that drive the effects. The present study examined the role of fearful expectancies and fear reduction (habituation) in VR exposure. Fearful expectancies were measured before, during (retrospectively), and after a VR exposure session in 121 participants with elevated fear of spiders. In addition, skin-conductance and heart rate were measured throughout the exposure session to examine fear reduction within the exercises and across the session. Fearful expectancies decreased after VR exposure. Larger decreases were associated with better outcomes 1 week (in the verbal and behavioral measures) and 3 months (in one of the verbal measures) after exposure. Levels of expectancies during exposure were not associated with the outcome. We did not find evidence that expectancies about own reactions were better testable in VR exposure than expectancies about the spider. Fear reduction within the exercises or across the session did generally not predict VR exposure outcome. It is recommended to focus on various operationalizations and experimental manipulations of the mechanisms, as well as to compare these mechanisms between VR and in vivo exposure in future research.

Emotional salience network involved in constructing two-dimensional fear space in humans

Fear learning is pivotal for organismal survival, ensuring the ability to avoid potential threats through learning based on experiencing minimal fear information. In reality, fear learning requires to form a structured representation of fear experiences from multiple dimensions in order to support flexible use in ever-changing environment. Yet, the underlying neural mechanisms of constructing dimensional fear space remain elusive. Here we set up an innovative approach with two-dimensional fear learning, by utilizing the probability (uncertainty) and subjective pain intensity of threatening mild electric shock with five levels of each dimension. Behaviorally, individuals constructed a two-dimensional fear space after learning phase, as evidenced by significant changes in participant's fearful ratings for each cue associated with a five-by-five grid after (relative to before) learning phase. Analysis of neuroimaging data revealed that the medial temporal lobe, in conjunction with the amygdala, the insula, the anterior cingulate cortex (ACC), the hippocampus, and the dorsolateral prefrontal cortex (dlPFC), collectively contribute to the construction of a two-dimensional fear space consisting of uncertainty and intensity. Activation in the parahippocampal gyrus, insula, and dlPFC was associated with mental navigation within two-dimensional fear space, whereas the engagement of insula, ACC, amygdala, the hippocampus, the dlPFC was associated with a unified fearful scoring cross uncertainty and intensity dimensions after fear learning. Our findings suggest a neurocognitive model through which emotional salience network underlies the construction of a structured representation of fear experiences from multiple dimensions.

Conscious expectancy rather than associative strength elicits brain activity during single-cue fear conditioning

The neurocognitive processes underlying Pavlovian conditioning in humans are still largely debated. The conventional view is that conditioned responses (CRs) emerge automatically as a function of the contingencies between a conditioned stimulus (CS) and an unconditioned stimulus (US). As such, the associative strength model asserts that the frequency or amplitude of CRs reflects the strength of the CS-US associations. Alternatively, the expectation model asserts that the presentation of the CS triggers conscious expectancy of the US, which is responsible for the production of CRs. The present study tested the hypothesis that there are dissociable brain networks related to the expectancy and associative strength theories using a single-cue fear conditioning paradigm with a pseudo-random intermittent reinforcement schedule during functional magnetic resonance imaging. Participants' (n = 21) trial-by-trial expectations of receiving shock displayed a significant linear effect consistent with the expectation model. We also found a positive linear relationship between the expectancy model and activity in frontoparietal brain areas including the dorsolateral prefrontal cortex (PFC) and dorsomedial PFC. While an exploratory analysis found a linear relationship consistent with the associated strength model in the insula and early visual cortex, our primary results are consistent with the view that conscious expectancy contributes to CRs.

Let's play pretend: Towards effective modelling in experimental psycho(patho)logy

BACKGROUND AND OBJECTIVES

Models are omnipresent in science. We introduce a novel framework to achieve more effective modelling practices in general psychology and experimental psychopathology.

METHOD

We analyze three types of models that are common in psychology: laboratory models, computational models, and cognitive models. We then evaluate two common ways to assess the translational value of models (phenomenological similarity and deep similarity) as well as an arguably underappreciated way (functional similarity). Functional similarity is based on an assessment of whether variables (e.g., the administration of a pharmacological substance) have a similar effect (a) in the model (e.g., in a fear conditioning procedure) and (b) on the real-life target phenomenon (e.g., on real-life anxiety complaints).

CONCLUSIONS

We argue that the assessment of functional similarity is a powerful tool to assess the translational value of models in the field of experimental psychopathology and beyond.

Learned Nocebo Effects on Cutaneous Sensations of Pain and Itch: A Systematic Review and Meta-analysis of Experimental Behavioral Studies on Healthy Humans

OBJECTIVE

In past decades, the field of nocebo research has focused on studying how sensory perception can be shaped by learning. Nocebo effects refer to aggravated sensory experiences or increased sensitivity to sensations such as pain and itch resulting from treatment-related negative experiences. Behavioral conditioning and verbal suggestions of a negative treatment outcome may aggravate pain and itch perception. Gaining a comprehensive view of the magnitude of nocebo effects and contributing factors will help steer nocebo research toward fruitful directions for understanding complex sensory phenomena.

METHODS

We conducted a systematic review and meta-analysis of a total of 37 distinct experimental nocebo studies on healthy participants (all published in English between 2008 and 2021), with four separate meta-analyses for nocebo effects on pain or itch. We conducted subgroup analyses and meta-regression on factors such as type and intensity of sensory stimuli, and length of conditioning paradigms.

RESULTS

This meta-analysis showed that, on average, effect sizes of nocebo effects were moderate to large (Hedges g between 0.26 and 0.71 for the four primary outcomes). The combination of conditioning and verbal suggestions yielded stronger nocebo responses on pain in particular. Subgroup analyses, including factors such as the type of sensory stimulation, did not explain the moderate heterogeneity in nocebo magnitudes between different studies. Risk of bias was generally low and was not related to nocebo magnitudes either.

CONCLUSIONS

We discuss these results in relation to the role of conditioning and aversive learning, and we recommend more consistency in designing and reporting nocebo experiments.

Beyond Fear, Extinction, and Freezing: Strategies for Improving the Translational Value of Animal Conditioning Research

Translational neuroscience for anxiety has had limited success despite great progress in understanding the neurobiology of Pavlovian fear conditioning and extinction. This chapter explores the idea that conditioning paradigms have had a modest impact on translation because studies in animals and humans are misaligned in important ways. For instance, animal conditioning studies typically use imminent threats to assess short-duration fear states with single behavioral measures (e.g., freezing), whereas human studies typically assess weaker or more prolonged anxiety states with physiological (e.g., skin conductance) and self-report measures. A path forward may be more animal research on conditioned anxiety phenomena measuring dynamic behavioral and physiological responses in more complex environments. Exploring transitions between defensive brain states during extinction, looming threats, and post-threat recovery may be particularly informative. If care is taken to align paradigms, threat levels, and measures, this strategy may reveal stable patterns of non-conscious defense in animals and humans that correlate better with conscious anxiety. This shift in focus is also warranted because anxiety is a bigger problem than fear, even in disorders defined by dysfunctional fear or panic reactions.

Fear Extinction as a Psychologist Views It

Fear extinction is a topic of central importance in translational neuroscience. It integrates knowledge from various disciplines, including clinical psychology, experimental psychology, psychiatry, cellular and systems neuroscience, and pharmacology. The experimental phenomenon of extinction was first discovered by Ivan P. Pavlov more than 100 years ago and still forms the basis for investigating the psychological and physiological mechanisms that drive extinction of fear. Here, I present old and new ways to think about fear conditioning and extinction from a psychologist's point of view. Extinction is a simple phenomenon with a complex machinery. Enhancing the behavioral analysis of extinction is necessary to advance research in neighboring disciplines as well and to increase our chances to develop extinction enhancers that might further improve efficacy of extinction-based therapies to treat dysfunctional fears. For that purpose, I address a number of fundamental questions in this chapter to clarify psychological viewpoints on the process of fear extinction. What is extinction? What is an association? What is fear? What can we learn from fear extinction? My goal is to reinforce critical thinking about basic assumptions underlying fear extinction and to open up new avenues for further research.

Appraising reconsolidation theory and its empirical validation

Re-exposure to elements of prior experiences can create opportunities for inducing amnesia for those events. The dominant theoretical framework posits that such re-exposure can result in memory destabilization, making the memory representation temporarily sensitive to disruption while it awaits reconsolidation. If true, such a mechanism that allows for memories to be permanently changed could have important implications for the treatment of several forms of psychopathology. However, there have been contradictory findings and elusive occurrences of replication failures within the "reconsolidation" field. Considering its potential relevance for clinical applications, the fact that this "hot" research area is being dominated by a single mechanistic theory, and the presence of unexplainable contradictory findings, we believe that it is both useful and timely to critically evaluate the reconsolidation framework. We discuss potential issues that may arise from how reconsolidation interference has typically been deducted from behavioral observations, and provide a principled assessment of reconsolidation theory that illustrates that the theory and its proposed boundary conditions are vaguely defined, which has made it close to impossible to refute reconsolidation theory. We advocate for caution, encouraging researchers not to blindly assume that a reconsolidation process must underlie their findings, and pointing out the risks of doing so. Finally, we suggest concrete theoretical and methodological advances that can promote a fruitful translation of reminder-dependent amnesia into clinical treatment.

EMDR Therapy and PTSD: A Goal-Directed Predictive Processing Perspective

Eye movement desensitization and reprocessing (EMDR) therapy is a widely used evidence-based treatment for posttraumatic stress disorder (PTSD). The mental processes underlying both PTSD and EMDR treatment effects are often explained by drawing on processes that involve the automatic formation and change of mental associations. Recent evidence that contrasts with these explanations is discussed and a new perspective to PTSD and EMDR treatment effects is proposed that draws on automatic inferential processes and can be readily integrated with the dominant (Adaptive Information Processing) model. This new perspective incorporates insights from cognitive theories that draw on predictive processing and goal-directed processes to elucidate (changes in) automatic inferences that underlie PTSD symptoms and EMDR treatment effects. Recommendations for clinical practice are provided based on this new perspective.

The (shared) features of fear: Toward the source of human fear responding

Little is known about why people behave the way they do in threatening situations. Some theories invoke a transfer of responses from unconditioned stimuli (US) to conditioned stimuli (CS), but this principle goes astray because responses to the US and CS can differ substantially. The idea that we introduce here is that the pattern of responses to a newly established CS does not come from the US but (at least partly) transfers from how one (learned to) respond(s) to previously encountered stimuli with threat value. So, we conceptualize threat value as a stimulus feature that allows responses to transfer between stimuli that share this feature (in the same way as, for example, overlap in color or shape can support transfer). In contrast to prevailing views, this new perspective focuses on the relation between the CS and already established threat signals rather than on the relation between the CS and the US. We discuss how this shared features perspective on human fear responding can inspire future directions in both the laboratory and clinical practice.

Reasons to remember: A functionalist view on the relation between memory and psychopathology

Memory is under investigation as one of the core mechanisms of psychopathology. The traditional cognitive view of memory as a stable structure with a range of set characteristics can be complemented with a perspective that considers remembering as a behaviour that varies fluidly across contexts. Remembering may serve adaptation to the environment by fulfilling a directive function, a self-function and a social function. A failure to fulfil these functions may be a risk factor for psychopathology. Implications of the discussed functionalist perspective include the importance of reinforcing adaptive ways of remembering during early development, the possibility of treating maladaptive ways of remembering through contextual interventions and the added ecological validity of using ambulatory assessment methods.

Behavioral and Physiological Evidence Challenges the Automatic Acquisition of Evaluations

Dual-learning theories of evaluations posit that evaluations can be automatically (i.e., efficiently, unconsciously, uncontrollably, and involuntarily) acquired. They also often assume the existence of evaluative-learning processes that are impervious to verbal information. In this article, we explain that recent research challenges both assertions for three categories of measures: explicit evaluative measures, implicit evaluative measures, and physiological measures of fear. In doing so, we also question the widespread assumption that implicit (i.e., typically behavioral and physiological) compared with explicit (i.e., self-reported) evaluative measures are indicative of the way evaluations are acquired. In the second part of the article, we discuss the practical implications of these recent findings.

Perceptual variability: Implications for learning and generalization

The generalization of learned behavior has been extensively investigated, but accounting for variance in generalized responding remains a challenge. Based on recent advances, we demonstrate that the inclusion of perceptual measures in generalization research may lead to a better understanding of both intra- and interindividual differences in generalization. We explore various ways through which perceptual variability can influence generalized responding. We investigate its impact on the ability to discriminate between stimuli and how similarity between stimuli may be variable, rather than fixed, because of it. Subsequently, we argue that perceptual variations can yield different learning experiences and that interindividual differences in generalized responding may be understood from this perspective. Finally, we point to the role of memory and decision-making within this context. Throughout this paper, we argue that accounting for perception in current generalization protocols will improve the precision of obtained generalization gradients and the ability to infer latent mechanisms. This can inspire future attempts to use generalization gradients as a (clinical) predictor or to relate them to individual traits and neural correlates and, ultimately, may lead to new theoretical and clinical insights.