Does US expectancy mediate the additive effects of CS-US pairings on contingency instructions? Results from subjective, psychophysiological and neural measures

Inferring danger with minimal aversive experience

Learning about threats is crucial for survival and fundamentally rests upon Pavlovian conditioning. However, Pavlovian threat learning is largely limited to detecting known (or similar) threats and involves first-hand exposure to danger, which inevitably poses a risk of harm. We discuss how individuals leverage a rich repertoire of mnemonic processes that operate largely in safety and significantly expand our ability to recognize danger beyond Pavlovian threat associations. These processes result in complementary memories - acquired individually or through social interactions - that represent potential threats and the relational structure of our environment. The interplay between these memories allows danger to be inferred rather than directly learned, thereby flexibly protecting us from potential harm in novel situations despite minimal prior aversive experience.

Safety behaviors toward innocuous stimuli can maintain or increase threat beliefs

Safety behaviors can prevent or minimize a feared outcome. However, in relatively safe situations, they may be less adaptive, presumably because people will misattribute safety to these behaviors. This research aimed to investigate whether safety behaviors in safe situations can lead to increased threat beliefs. In Study 1, we aimed to replicate a fear conditioning study (N = 68 students) in which the experimental, but not the control group, received the opportunity to perform safety behavior to an innocuous stimulus. From before to after the availability of the safety behavior, threat beliefs persisted in the experimental group, while they decreased in the control group. In Study 2, we examined whether threat beliefs had actually increased for some individuals in the experimental group, using a multi-dataset latent class analysis on data from Study 1 and two earlier studies (N = 213). Results showed that about a quarter of individuals who performed safety behavior toward the innocuous stimulus showed increased threat expectancy to this cue, while virtually nobody in the control group exhibited an increase. Taken together, safety behavior in relatively safe situations may have maladaptive effects as it generally maintains and sometimes even increases threat beliefs.

Rating expectations can slow aversive reversal learning

The process of learning allows organisms to develop predictions about outcomes in the environment, and learning is sensitive to both simple associations and higher order knowledge. However, it is unknown whether consciously attending to expectations shapes the learning process itself. Here, we directly tested whether rating expectations shapes arousal during classical conditioning. Participants performed an aversive learning paradigm wherein one image (CS+) was paired with shock on 50% of trials, while a second image (CS-) was never paired with shock. Halfway through the task, contingencies reversed. One group of participants rated the probability of upcoming shock on each trial, while the other group made no online ratings. We measured skin conductance response (SCR) evoked in response to the CS and used traditional analyses as well as quantitative models of reinforcement learning to test whether rating expectations influenced arousal and aversive reversal learning. Participants who provided online expectancy ratings displayed slower learning based on a hybrid model of adaptive learning and reduced reversal of SCR relative to those who did not rate expectations. Mediation analysis revealed that the effect of associative learning on SCR could be fully explained through its effects on subjective expectancy within the group who provided ratings. This suggests that the act of rating expectations reduces the speed of learning, likely through changes in attention, and that expectations directly influence arousal. Our findings indicate that higher order expectancy judgments can alter associative learning.

Old Fears Die Hard: Return of Public Speaking Fear in a Virtual Reality Procedure

Exposure-based therapy is an effective treatment for social anxiety, but some patients relapse. We used a novel virtual reality procedure to examine spontaneous recovery (i.e., a return of fear over time) and fear renewal (i.e., the return of fear after a context switch) in individuals with fear of public speaking. On Day 1, 32 participants received exposure training before a virtual audience. On Day 8, participants completed a spontaneous recovery phase, followed by a fear renewal test, in which they gave a presentation in front of a new (context switch) or the same audience (no context switch). After exposure, participants exhibited a lower heart rate, subjective distress, negative valence, and arousal. One week later, participants showed spontaneous recovery of heart rate, and the context switch group showed renewal of subjective distress, negative valence, and arousal. Future studies can use this procedure to test interventions aimed at improving long-term exposure effects in individuals with public speaking fear.

REVERSE phenotyping-Can the phenotype following constitutive Tph2 gene inactivation in mice be transferred to children and adolescents with and without adhd?

INTRODUCTION

Experimental models of neuropsychiatric disorders, for example, ADHD, are used to mimic specific phenotypic traits of a complex human disorder. However, it remains unresolved to what extent the animal phenotype reflects the specific human trait. The null mutant mouse of the serotonin-synthesizing tryptophan hydroxylase-2 (Tph2^-/- ) gene has been proposed as experimental model for ADHD with high face validity for impulsive, aggressive, and anxious behaviors. To validate this ADHD-like model, we examined the Tph2^-/- phenotype in humans when considering allelic variation of TPH2 function ("reverse phenotyping").

METHODS

58 participants (6 females, 8-18 years) were examined, of whom 32 were diagnosed with ADHD. All participants were phenotyped for impulsivity, aggression, and anxiety using questionnaires, behavioral tests, and MRI scanning while performing the 4-choice serial reaction time task. Additionally, participants were genotyped for the TPH2 G-703T (rs4570625) polymorphism. To analyze the relation between TPH2 G-703T variants and the impulsive/aggressive/anxious phenotype, mediation analyses were performed using behavioral and MRI data as potential mediators.

RESULTS

We found that the relation between TPH2 G-703T and aggression as part of the reverse Tph2^- /^- phenotype was mediated by structure and function of the right middle and inferior frontal gyrus.

CONCLUSION

At the example of trait aggression, our results support the assumption that the Tph2 null mutant mouse reflects the TPH2 G-703T-dependent phenotype in humans. Additionally, we conclude that "reverse phenotyping" is a promising method to validate experimental models and human findings for refined analysis of disease mechanisms.

Optimizing exposure: Between-session mental rehearsal as an augmentation strategy

Exposure therapy is widely empirically supported as a treatment for anxiety disorders, but clinically significant response rates hover around 50%. This study explores strategies for consolidating the exposure memory as a way of improving efficacy. Between-session mental rehearsal of exposure learning was examined as a way of enhancing the effects of exposure therapy. Sixty-two spider-fearful individuals completed baseline questionnaires and a behavioral approach test with a live tarantula, followed by two sessions of in vivo exposures, and a post-assessment one-week later that repeated the baseline questionnaires and behavioral approach test. Skin conductance, subjective distress, and number of steps completed were recorded at each behavioral approach test. Participants were randomized to mental rehearsal or control (non-specific) rehearsal that was prompted on three occasions after each exposure session. Participants in both conditions improved from baseline to post-assessment, but mental rehearsal participants showed significantly greater improvement than control participants across questionnaire measurements of spider fear, subjective distress, and number of steps completed during the behavioral approach test. Findings suggest that between-session mental rehearsal is an effective supplement to exposure therapy. As such, mental rehearsal may be a promising avenue toward increasing treatment response rates across many psychiatric disorders that benefit from exposure therapy.

Measuring fear: Association among different measures of fear learning

BACKGROUND AND OBJECTIVES

Fear conditioning paradigms use various measures to assess learned fear, including autonomic arousal responses like skin conductance, and self-reports of both associative (US-expectancies) and evaluative (affective ratings) learning. The present study uses a dimensional approach to examine associations among fear indices directly.

METHODS

Seventy-three participants completed a differential fear conditioning experiment, during which a neutral stimulus (CS+) was paired with an electric shock (US), while another stimulus (CS-) was never paired with the shock (partially instructed fear acquisition). Ten minutes later, both stimuli were presented without any shocks (fear extinction). Skin conductance responses and US-expectancy ratings were recorded during each phase, while self-reported negative affect was assessed for each CS at the end of extinction.

RESULTS

Results showed a positive association among US-expectancy ratings and skin conductance responses during acquisition and early extinction. US-expectancy ratings during overall extinction were positively associated with post-extinction negative affect.

LIMITATIONS

The lack of affective ratings post-acquisition may have obscured associations between associative and evaluative learning indices.

CONCLUSIONS

Results provide evidence for the expected correspondence among different indices of associative fear learning. Findings emphasize the need for incorporating both associative and evaluative learning measures in fear conditioning paradigms.

Making translation work: Harmonizing cross-species methodology in the behavioural neuroscience of Pavlovian fear conditioning

Translational neuroscience bridges insights from specific mechanisms in rodents to complex functions in humans and is key to advance our general understanding of central nervous function. A prime example of translational research is the study of cross-species mechanisms that underlie responding to learned threats, by employing Pavlovian fear conditioning protocols in rodents and humans. Hitherto, evidence for (and critique of) these cross-species comparisons in fear conditioning research was based on theoretical viewpoints. Here, we provide a perspective to substantiate these theoretical concepts with empirical considerations of cross-species methodology. This meta-research perspective is expected to foster cross-species comparability and reproducibility to ultimately facilitate successful transfer of results from basic science into clinical applications.

Renewal of conditioned fear responses using a film clip as the aversive unconditioned stimulus

BACKGROUND AND OBJECTIVES

Pavlovian fear conditioning paradigms are valuable to investigate fear learning and the return of extinguished fear in the lab. However, their validity is limited, because the aversive stimuli (e.g., electric shocks) typically lack the modalities and complexity of real-world aversive experiences. To overcome this limitation, we examined fear acquisition, extinction and contextual renewal using an audiovisual unconditioned stimulus (US).

METHOD

On day 1, 50 healthy participants completed an acquisition phase in a specific context (i.e., desk or bookcase, 'context A'). Pictures of colored lamps served as conditioned stimuli and an aversive film clip was used as US. On day 2, extinction took place in the same context ('context A') or in a different context ('context B'). Afterwards, renewal was tested in the acquisition context (AAA vs. ABA design).

RESULTS

As hypothesized, fear acquisition and extinction, as measured by US expectancy ratings, fear potentiated startle (FPS), and skin conductance responses (SCRs), were successful. Most importantly, conditioned responding was renewed on all measures in the ABA condition, but not in the AAA condition. Differential renewal (i.e., larger renewal for CS + than for CS-) was only observed for US expectancy ratings.

LIMITATIONS

The return of conditioned responses was non-differential for FPS and SCR.

CONCLUSIONS

The current set-up enables investigation of fear renewal using an audiovisual US. Future studies can utilize this paradigm to investigate interventions that aim to reduce fear renewal by modifying the US memory, such as Eye Movement Desensitization and Reprocessing and imagery rescripting.

Low Perceived Self-Efficacy Impedes Discriminative Fear Learning

Perceived self-efficacy refers to a subject’s expectation about the outcomes his/her behavior will have in a challenging situation. Low self-efficacy has been implicated in the origins and maintenance of phobic behavior. Correlational studies suggest an association between perceived self-efficacy and learning. The experimental manipulation of perceived self-efficacy offers an interesting approach to examine the impact of self-efficacy beliefs on cognitive and emotional functions. Recently, a positive effect of an experimentally induced increased self-efficacy on associative learning has been demonstrated. Changes in associative learning constitute a central hallmark of pathological fear and anxiety. Such alterations in the acquisition and extinction of conditioned fear may be related to cognitive and neurobiological factors that predict a certain vulnerability to anxiety disorders. The present study builds on previous own work by investigating the effect of an experimentally induced low perceived self-efficacy on fear acquisition, extinction and extinction retrieval in a differential fear conditioning task. Our results suggest that a negative verbal feedback, which leads to a decreased self-efficacy, is associated with changes in the acquisition of conditioned fear. During fear acquisition, the negative verbal feedback group showed decreased discrimination of fear responses between the aversive and safe conditioned stimuli (CS) relative to a group receiving a neutral feedback. The effects of the negative verbal feedback on the acquisition of fear discrimination learning were indexed by an impaired ability to discriminate the probability of receiving a shock during acquisition upon presentation of the aversive (CS+) relative to the safe stimuli (CS−). However, the effects of low self-efficacy on discrimination learning were limited to fear acquisition. No differences between the groups were observed during extinction and extinction retrieval. Furthermore, analysis of other outcome measures, i.e., skin conductance responses and CS valence ratings, revealed no group differences during the different phases of fear conditioning. In conclusion, lower perceived self-efficacy alters cognitive/expectancy components of discrimination during fear learning but not evaluative components and physiological responding. The pattern of findings suggests a selective, detrimental role of low(er) self-efficacy on the subject’s ability to learn the association between ambiguous cues and threat/safety.