Reducing Generalization of Conditioned Fear: Beneficial Impact of Fear Relevance and Feedback in Discrimination Training

Fear generalization predicts post-traumatic stress symptoms: A two-year follow-up study in Dutch fire fighters

INTRODUCTION

Excessive fear generalization has been associated with pathological anxiety, including posttraumatic stress disorder (PTSD). However, studies investigating the longitudinal relationship between generalization and the development of anxiety symptomatology are scarce. This study aims to test the predictive value of fear generalization for PTSD symptoms in a high-risk profession sample and to explore the relationship between generalization and neuroticism, which are both linked to PTSD.

METHOD

Longitudinal data from a multi-wave study in 529 Dutch fire-fighters were used. Fear generalization, PTSD symptoms and neuroticism were assessed at baseline. PTSD symptoms were reevaluated at six, 12, 18, and 24 months. Generalization was assessed in a differential conditioning paradigm by measuring expectancies of an aversive outcome when presented with stimuli similar to previously conditioned stimuli.

RESULTS

Higher expectancy ratings towards stimuli most similar to safety signals predicted PTSD symptoms at follow-up after controlling for baseline PTSD symptoms, whereas higher expectancy ratings towards stimuli most similar to danger signals was associated with neuroticism. Neuroticism weakened the predictive power of fear generalization when considered simultaneously.

DISCUSSION

These findings suggest that heightened fear generalization is associated with the development of anxiety and trauma-related symptoms. Targeting problematic fear generalization may be a promising intervention approach.

Fear in action: Fear conditioning and alleviation through body movements

Fear memories enhance survival especially when the memories guide defensive movements to minimize harm. Accordingly, fear memories and body movements have tight relationships in animals: Fear memory acquisition results in adapting reactive defense movements, while training active defense movements reduces fear memory. However, evidence in humans is scarce because their movements are typically suppressed in experiments. Here, we tracked adult participants' body motions while they underwent ecologically valid fear conditioning in a 3D virtual space. First, with body motion tracking, we revealed that distinct spatiotemporal body movement patterns emerge through fear conditioning. Second, subsequent training to actively avoid threats with naturalistic defensive actions led to a long-term (24 h) reduction of physiological and embodied conditioned responses, while extinction or vicarious training only transiently reduced the responses. Together, our results highlight the role of body movements in human fear memory and its intervention.

Enhanced late positive potential to conditioned threat cue during delayed extinction in anxious youth

BACKGROUND

Deficits in threat learning relate to anxiety symptoms. Since several anxiety disorders arise in adolescence, impaired adolescent threat learning could contribute to adolescent changes in risk for anxiety. This study compared threat learning among anxious and non-anxious youth using self-reports, peripheral psychophysiology measures, and event-related potentials. Because exposure therapy, the first-line treatment for anxiety disorders, is largely based on principles of extinction learning, the study also examined the link between extinction learning and treatment outcomes among anxious youth.

METHODS

Clinically anxious (n = 28) and non-anxious (n = 33) youth completed differential threat acquisition and immediate extinction. They returned to the lab a week later to complete a threat generalization test and a delayed extinction task. Following these two experimental visits, anxious youth received exposure therapy for 12 weeks.

RESULTS

Anxious as compared to non-anxious youth demonstrated elevated cognitive and physiological responses across acquisition and immediate extinction learning, as well as greater threat generalization. In addition, anxious youth showed enhanced late positive potential response to the conditioned threat cue compared to the safety cue during delayed extinction. Finally, aberrant neural response during delayed extinction was associated with poorer treatment outcomes.

CONCLUSIONS

The study emphasizes differences between anxious and non-anxious youth in threat learning processes and provides preliminary support for a link between neural processing during delayed extinction and exposure-based treatment outcome in pediatric anxiety.

No influence of threat uncertainty on fear generalization

Fear overgeneralization and perceived uncertainty about future outcomes have been suggested as risk factors for clinical anxiety. However, little is known regarding how they influence each other. In this study, we investigated whether different levels of threat uncertainty influence fear generalization. Three groups of healthy participants underwent a differential fear conditioning protocol followed by a generalization test. All groups learned to associate one female face (conditioned stimulus, CS+) with a female scream (unconditioned stimulus, US), whereas the other face (CS-) was not associated with the scream. In order to manipulate threat uncertainty, one group (low uncertainty, n = 26) received 80%, the second group (moderate uncertainty, n = 32) received 60%, and the third group (high uncertainty, n = 30) 40% CS-US contingency. In the generalization test, all groups saw CS+ and CS- again along with four morphs resembling the CSs in steps of 20%. Subjective (expectancy, valence, and arousal ratings), psychophysiological (skin conductance response, SCR), and visuocortical (steady-state visual evoked potentials, ssVEPs) indices of fear were registered. Participants expected the US according to their reinforcement schedules and the discriminative responses to CS+/CS- increased with more uncertainty in skin conductance. However, acquisition of conditioned fear was not evident in ssVEPs. During the generalization test, we found no effect of threat uncertainty in any of the measured variables, but the strength of generalization for threat expectancy ratings was positively correlated with dispositional intolerance of uncertainty. This study suggests that mere threat uncertainty does not modulate fear generalization.

Learned industriousness as a translational mechanism in anorexia nervosa

It remains unexplained why some behaviours persist despite being non-hedonic and ostensibly aversive. This phenomenon is especially baffling when such behaviours are taken to excess in the form of psychopathology. Anorexia nervosa is one psychiatric disorder in which effortful behaviours that most people find unpleasant (suchas restrictive eating) are persistently performed. We propose thatthe social psychology theory of learned industriousness providesa novel mechanistic account for such phenomena. This theoryposits that high-effort behaviour can be conditioned to acquire secondary reinforcing properties through repeated pairing with reward. Accordingly, effort sensations become less aversive andmore appetitive, increasing willingness to engage in effortful behaviour. In this Perspective, we review pre-clinical behaviouraland biological data that support learned industriousness, contrast learned industriousness with other models of non-hedonic persistence (such as habit learning), highlight evidence that supports learned industriousness in individuals with anorexia nervosa and consider implications of the model, including translation to other psychiatric presentations.

Know Your Movements: Poorer Proprioceptive Accuracy is Associated With Overprotective Avoidance Behavior

Pain-related avoidance of movements that are actually safe (ie, overprotective behavior) plays a key role in chronic pain disability. Avoidance is reinforced through operant learning: after learning that a certain movement elicits pain, movements that prevent pain are more likely to be performed. Proprioceptive accuracy importantly contributes to motor learning and memory. Interestingly, reduced accuracy has been documented in various chronic pain conditions, prompting the question whether this relates to avoidance becoming excessive. Using robotic arm-reaching movements, we tested the hypothesis that poor proprioceptive accuracy is associated with excessive pain-related avoidance in pain-free participants. Participants first performed a task to assess proprioceptive accuracy, followed by an operant avoidance training during which a pain stimulus was presented when they performed one movement trajectory, but not when they performed another trajectory. During a test phase, movements were no longer restricted to 2 trajectories, but participants were instructed to avoid pain. Unbeknownst to the participants, the pain stimulus was never presented during this phase. Results supported our hypothesis. Furthermore, exploratory analyses indicated a reduction in proprioceptive accuracy after avoidance learning, which was associated with excessive avoidance and higher trait fear of pain. PERSPECTIVE: This study is the first to show that poorer proprioceptive accuracy is associated with excessive pain-related avoidance. This finding is especially relevant for chronic pain conditions, as reduced accuracy has been documented in these populations, and points toward the need for research on training accuracy to tackle excessive avoidance.