Imagery Rescripting Versus Extinction: Distinct and Combined Effects on Expectancy and Revaluation Learning

Anxiety disorders are effectively treated with exposure therapy, but relapse remains high. Fear may reinstate after reoccurrence of the negative event because the expectancy of the aversive outcome (unconditioned stimulus [US]) is adjusted but not its evaluation. Imagery rescripting (ImRs) is an intervention that is proposed to work through revaluation of the US. The aim of our preregistered study was to test the effects of ImRs and extinction on US expectancy and US revaluation. Day 1 ( n = 106) consisted of acquisition with an aversive film clip as US. The manipulation (ImRs + extinction, extinction-only, or ImRs-only) took place on Day 2. Reinstatement of fear was tested on Day 3. Results showed expectancy learning in both extinction conditions but not in the ImRs-only condition and no enhanced revaluation learning in ImRs. The combination of ImRs and extinction slowed down extinction but did not protect against reinstatement, which pleads in favor of stand-alone interventions in clinical practice.

Reactivation of hedonic but not sensory representations in human emotional learning

Learning which stimuli in our environment co-occur with painful or pleasurable events is critical for survival. Previous research has established the basic neural and behavioural mechanisms of aversive and appetitive conditioning; however, it is unclear what precisely is learned. Here we examined what aspects of the unconditioned stimulus (US), sensory and hedonic, are transferred to the conditioned stimulus (CS). To decode the content of brain activation patterns elicited during appetitive (soft touch) and aversive (painful touch) conditioning of faces, a novel variation of representational similarity analysis (RSA) based on theoretically driven representational patterns of interest (POIs) was applied to fMRI data. Once face associations were learned through conditioning, globally the CS reactivated US representational patterns showing conditioning dependent reactivation. More specifically, in higher order brain regions, the CS only reactivated hedonic but not sensory aspects of the US, suggesting that affective conditioning primarily carries forward the valence of the experience rather than its sensory origins.

The influence of the initial reinforcement value on physiological parameters of conditioned respiratory reflex

BACKGROUND: Most of the studies of the role of reinforcement in the formation of adaptive behavior were performed on animals. At the same time, such an experimental model as a conditioned respiratory reflex to resistive load, has not been sufficiently studied, although an unconditioned reflex to additional resistance to breathing, on the basis of which a conditioned one is formed, is a stable reaction that has clear quantitative evaluation criteria, and the conditioned reflex itself is relatively strong, easily normalized, reluctantly extinguished and does not require observance of a number of methodological conditions. AIM: To study the influence of the initial value of reinforcement on the physiological parameters of the conditioned respiratory reflex. MATERIALS AND METHODS: The work was carried out on people of both genders, 16 people, aged 18 to 44, practically healthy. The unconditioned stimulus was applied in four gradations of external respiratory resistance: 11; 28; 54; 76 cm water • l/sec. The conditioned reflex was formed by the classic type, the duration of application of the conditioned stimulus was not fixed and its end coincided with the end of the action of the unconditioned stimulus, the period of the isolated action of the conditioned signal was 10 sec. As physiological parameters, we studied the ventilatory and motor parameters of respiration, the temporal parameters of the conditioned reaction. RESULTS: The influence of the unconditioned stimulus on the value of the tidal volume after the combination in all subjects depended on the absolute reinforcement values used in this combination, and was weakly connected with the initial reinforcement value. The influence of the external resistance on breathing used in this combination was significantly higher on such parameters as intraoral pressure of inspiration and expiration; the role of the initial reinforcement value in the dynamics of the given parameters was not confirmed. CONCLUSIONS: Most “sensitive” to the action of the initial value of the resistive load were the temporal parameters of the conditioned respiratory reflex — the latent period and the time of the conditioned reaction; the parameters of the “ventilatory” and “motor” outputs of the external respiration system changed noticeably, the spirometric parameters showed very little dynamics, and the capnographic parameters practically did not change. The dynamics of the parameters of the conditioned respiratory reflex to increased external respiratory resistance permits to single out groups of signs that have the greatest semantic significance for evaluation of the system-forming and discriminating role of the initial gradation of the reinforcement factor.

Higher-Order Conditioning: What Is Learnt and How it Is Expressed

Pairing a neutral conditioned stimulus (CS) with a motivationally significant unconditioned stimulus (US) results in the CS coming to elicit conditioned responses (CRs). The widespread significance and translational value of Pavlovian conditioning are increased by the fact that pairing two neutral CSs (A and X) enables conditioning with X to affect behavior to A. There are two traditional informal accounts of such higher-order conditioning, which build on more formal associative analyses of Pavlovian conditioning. But, higher-order conditioning and Pavlovian conditioning have characteristics that are beyond these accounts: Notably, the two are influenced in different ways by the same experimental manipulations, and both generate conditioned responses that do not reflect the US per se. Here, we present a formal analysis that sought to address these characteristics.

Simulation-based learning shapes real-life attitudes

Humans can vividly simulate hypothetical experiences. This ability draws on our memories (e.g., of familiar people and locations) to construct imaginings that resemble real-life events (e.g., of meeting a person at a location). Here, we examine the hypothesis that we also learn from such simulated episodes much like from actual experiences. Specifically, we show that the mere simulation of meeting a familiar person (unconditioned stimulus; US) at a known location (conditioned stimulus; CS) changes how people value the location. We provide key evidence that this simulation-based learning strengthens pre-existing CS-US associations and that it leads to a transfer of valence from the US to the CS. The data thus highlight a mechanism by which we learn from simulated experiences.

Temporal Factors Modulate Haloperidol-Induced Conditioned Catalepsy

Repeated pairings of a neutral context and the effects of haloperidol give rise to conditioned catalepsy when the context is subsequently presented in a drug-free test. In order to confirm whether this response is based on Pavlovian processes, we conducted two experiments involving two manipulations that affect conditioning intensity in classical conditioning procedures: time of joint exposure to the conditioned and the unconditioned stimulus, and the length of the inter-stimulus interval (ISI). The results revealed that both an increase in the length of context-drug pairings during conditioning and a reduced ISI between drug administration and context exposure increased conditioned catalepsy. These results are discussed in terms of the temporal peculiarities of those procedures that involve drugs as the unconditioned stimulus along with the role of Pavlovian conditioning in context-dependent catalepsy.

Peripheral cortisol administration blunts reward arousal but heightens anxiety-like arousal in marmosets

AimsExcess hypothalamic-pituitary-adrenal (HPA) axis activation is common in people with major depression and generalised anxiety disorder. We sought to determine whether higher circulating levels of the glucocorticoid cortisol are causally related to the expression of anhedonia-like and anxiety-like behaviours in marmosets.MethodFour marmosets (two male, two female) took part in the study. Cortisol and saline control injections were administered intramuscularly and salivary cortisol samples were taken before and after injections to determine if circulating cortisol levels changed from pre- to post-injection. To measure anhedonia-like behaviours, we trained marmosets on an appetitive Pavlovian conditioning paradigm, where animals learn to associate two anticipatory auditory cues (conditioned stimulus + or conditioned sitmulus -, CS+ or CS-) with the presence or absence of food reward (unconditioned stimulus + or unconditioned stimulus -, US+ or US-). Using cardiovascular telemetry probes and video cameras, we recorded animals' cardiovascular and behavioural arousal in freely moving conditions, comparing the injection of saline control versus 5mg/kg, 10mg/kg or 20mg/kg intramuscular cortisol. To measure anxiety-like behaviours, we used a human intruder (HI) paradigm, where marmosets are confronted with an unfamiliar human in their home cage. We recorded their behaviour on video cameras after saline control or 20mg/kg intramuscular cortisol. We used an exploratory-factor analysis (EFA) to determine how marmosets' behaviours towards the intruder loaded onto an 'anxiety-like' score. We then compared these scores under saline control versus cortisol conditions. Significance was set at p < 0.05.ResultUnlike saline control, we found that subcutaneous injections of 20 mg/kg cortisol successfully elevated peripheral cortisol concentrations to levels equivalent to peak circadian concentrations (p = 0.023). In the appetitive setting, 5 mg/kg, 10 mg/kg and 20 mg/kg cortisol injections blunted anticipatory (CS+ induced) increases in behavioural arousal (p = 0.004) but did not alter anticipatory cardiovascular arousal. Consummatory behavioural and cardiovascular arousal also remained intact. In the HI test, 20 mg/kg cortisol injections moderately increased anxiety towards the intruder as measured by an increase in marmosets' EFA-derived anxiety-like scores (p = 0.035).ConclusionIn marmosets, elevated peripheral cortisol levels are causally related to the behavioural features of blunted reward anticipation together with elevated anxiety-like behaviours characteristic of mood and anxiety disorders. Future work will characterise the neuroimaging changes induced by elevated peripheral cortisol levels and identify the regions of the prefrontal cortex contributing to HPA axis regulation and dysregulation.

Serotonin depletion reduces both acquisition and expression of context-conditioned fear

Objective: Whereas numerous experimental and clinical studies suggest a complex involvement of serotonin in the regulation of anxiety, it remains to be clarified if the dominating impact of this transmitter is best described as anxiety-reducing or anxiety-promoting. The aim of this study was to assess the impact of serotonin depletion on acquisition, consolidation, and expression of conditioned fear. Methods: Male Sprague–Dawley rats were exposed to foot shocks as unconditioned stimulus and assessed with respect to freezing behaviour when re-subjected to context. Serotonin depletion was achieved by administration of a serotonin synthesis inhibitor, para-chlorophenylalanine (PCPA) (300 mg/kg daily × 3), (i) throughout the period from (and including) acquisition to (and including) expression, (ii) during acquisition but not expression, (iii) after acquisition only, and (iv) during expression only. Results: The time spent freezing was significantly reduced in animals that were serotonin-depleted during the entire period from (and including) acquisition to (and including) expression, as well as in those being serotonin-depleted during either acquisition only or expression only. In contrast, PCPA administrated immediately after acquisition, that is during memory consolidation, did not impact the expression of conditioned fear. Conclusion: Intact serotonergic neurotransmission is important for both acquisition and expression of context-conditioned fear.