条件性恐惧泛化的性别差异

恐惧的过度泛化是焦虑障碍的核心症状之一, 表现为患者对与原危险刺激极不相似的中性刺激也有着较高强度的恐惧反应。临床上, 女性比男性更有可能患焦虑障碍, 因而对恐惧泛化进行性别差异研究可以为解释女性有着更高焦虑障碍发病率提供新的角度, 同时为临床治疗提供参考。本研究采用辨别性条件恐惧范式, 以主观预期值和皮电反应值作为测量指标, 从行为和生理两个层面对条件性恐惧泛化程度和恐惧泛化消退的性别差异进行研究。结果发现, 在恐惧泛化程度上, 未出现显著性别差异。在恐惧泛化消退上, 在主观预期值和皮电反应值两个层面均有着显著性别差异, 具体表现为相较于男性, 女性恐惧泛化的消退更慢, 持续时间更长。研究结果表明, 女性焦虑障碍高发病率的潜在影响因素之一可能在于女性对于恐惧泛化刺激的难以消除。     

Effects of multiple contexts and context similarity on the renewal of extinguished conditioned behaviour in an ABA design with humans

The ABA renewal procedure involves pairing a conditional stimulus (CS) and an unconditional stimulus (US) in one context (A), presenting extinction trials of the CS alone in a second context (B), and nonreinforced test trials of the CS in the acquisition context (A). The renewal of extinguished conditioned behaviour is observed during test. The current study tested the effects of multiple extinction contexts and context similarity in attenuating renewal. Participants (N = 99) took part in a fear conditioning ABA renewal procedure. Using a measure of self-reported expectancy of the US, ABA renewal was observed when a single extinction context that was dissimilar to the test context was used. Renewal was attenuated, though still present, when extinction occurred in multiple dissimilar extinction contexts or in a single extinction context that was similar to the test context. Renewal was completely abolished when multiple extinction contexts that were similar to the test context were combined. Multiple extinction contexts and context similarity act additively in their effect on attenuating renewal. The results are discussed in relation to the design of exposure therapy programs that seek to reduce relapse that can occur via renewal.     

An experimental demonstration of AAB renewal in children with autism spectrum disorder

Operant renewal is a return of extinguished behavior due to changes in contextual stimuli that control the occurrence or nonoccurrence of a response. Well‐established in classical conditioning and operant research, renewal presents itself in three forms—ABA, ABC, and AAB—and poses threats to treatment maintenance where extinction procedures are utilized. As AAB renewal may be less likely to occur than ABA or ABC renewal, the current study sought to determine if AAB renewal would occur with three participants with Autism Spectrum Disorder who were taught a simple lever pull response. Results showed that lever pulls increased for two of three participants when we introduced novel stimuli (i.e., a light and a buzzer) to alter the contextual environment after extinction. These findings suggest that AAB renewal may account for some instances of response recovery after extinction and that the procedure of this study may be beneficial to the further study of renewal and the variables that affect its occurrence within a translational model.     

Renewal of Extinguished Lever-Press Responses upon Return to the Training Context

Two experiments with rats explored renewal effects in operant conditioning preparations. When pressing a lever was trained in one context and then extinguished in a second context, the responding was renewed by returning to the original context (ABA renewal) in Experiment 1. This finding was replicated in Experiment 2 with discriminative operant performance signaled by a localized light cue. In spite of the successful demonstration of ABA renewal effect in these experiments, AAB renewal was detected in neither experiment: When the responses had been extinguished in the context of acquisition, testing the rats in a second context did not renew the responses. The demonstration of ABA renewal but no AAB renewal suggests that extinction in another context and/or a return to the original context are critical for renewal of extinguished operant performance.     

Return of experimentally induced chocolate craving after extinction in a different context: divergence between craving for and expecting to eat chocolate

Unlike in fear conditioning, little attention has been devoted to extinction and renewal in appetitive conditioning, despite its relevance for extinction-based addiction treatments. We developed a paradigm, using a specific tray as a conditioned stimulus (CS) for eating chocolate (unconditioned stimulus, US), to investigate the effects of context change on acquisition and extinction of conditioned chocolate craving using an ABA renewal design. In Study 1 (n=32), participants successfully acquired chocolate craving, but unlike what is commonly observed in fear conditioning, craving did not extinguish. In Study 2, we separately assessed craving and US expectancy in a between-subjects design (n=64). US-expectancy data showed acquisition, extinction and renewal in the ABA group. The craving data did not follow this pattern, suggesting different mechanisms for craving and US expectancy. Similarities and differences between craving and US expectancy, as well as practical implications, are discussed.     

状态焦虑对条件性恐惧泛化的影响

恐惧的过度泛化是焦虑障碍患者重要的潜在病因,探索焦虑对恐惧泛化的影响具有重要意义。本研究在恐惧习得后,通过恐惧创伤电影范式诱发状态焦虑组被试的焦虑水平,采用主观预期值和皮电反应值作为指标,考察状态焦虑对条件性恐惧泛化的影响。结果表明,恐惧创伤电影范式显著提高了状态焦虑组被试的焦虑水平。在泛化阶段,状态焦虑组被试表现出更强的恐惧泛化,对与条件刺激相似的泛化刺激表现出更强烈的恐惧以及更高的预期。状态焦虑使得被试恐惧泛化的消退更慢,持续时间更长。研究同时发现,在状态焦虑下,被试对条件刺激的辨识出现增强趋势。研究结果提示在对经历负性事件个体进行临床干预时,可通过降低其焦虑水平来减少过度泛化。     

The effects of physical context changes and multiple extinction contexts on two forms of renewal in a conditioned suppression task with humans

Three experiments examined the effects of physical context changes and multiple extinction contexts on the renewal of conditioned suppression in humans. A conditioned suppression task used an undesirable event as the unconditional stimulus (US). One conditional stimulus (CS+) predicted the occurrence of the US and another (CS−) predicted US absence. In Experiment 1 (N = 32), conditioned suppression was acquired to the CS+ in one context and extinguished in a different context. An increase in suppression was found for the CS+ and not for the CS− when subsequent test trials were conducted in the acquisition context (ABA renewal). Experiment 2 (N = 32) tested for ABC Renewal and showed increased suppression to both the CS+ and CS− when test was conducted in a novel context. Experiment 3 (N = 80) showed that these two effects were abolished when extinction was conducted in multiple contexts. The experiments extend the ABA renewal of conditioned suppression found with non-human animal subjects and the reduction of renewal by extinction in multiple contexts. Context changes may also facilitate cue competition effects after training with elementary stimuli, as shown by the effects of US omission in the ABA and ABC renewal groups.     

Extinction treatment in multiple contexts attenuates ABC renewal in humans

Renewal has been implicated as one of the underlying mechanisms in return of fear following exposure therapy. ABC renewal is clinically more relevant than ABA renewal and yet it is a weaker form of renewal, suggesting that conducting extinction treatment in multiple contexts may be sufficient to attenuate ABC renewal. Using self-reported expectancy of shock and startle blink responses the current study examined the effects of conducting extinction treatment in multiple contexts on ABC fear renewal. Participants (N = 68) received conditional stimulus (CS) and unconditional stimulus (US) pairings in one context (A) followed by extinction treatment (CS presentations alone) in either one other context (B) or three other contexts (BCD). Non-reinforced test trials in a novel context (E) resulted in renewal of extinguished conditioned behaviour for those who received extinction in only one context. However, renewal was attenuated for those who received extinction treatment in three contexts. No renewal was found for the control group that received the test trial in the same context as during extinction. Suggestions are provided for clinicians seeking to prevent or attenuate return of fear following exposure therapy.     

Kappa opioid receptors mediate where fear is expressed following extinction training

Six experiments used a within-subjects renewal design to examine the involvement of kappa opioid receptors (KORs) in regulating the expression and recovery of extinguished fear. Rats were trained to fear a tone conditioned stimulus (CS) via pairings with foot shock in a distinctive context (A). This was followed by extinction training of the CS in a second context (B). Finally, all rats were tested for fear to the tone in the extinction context (ABB) and the training (ABA) or a novel (ABC) context. Intracerebroventricular (ICV) infusion of the KOR antagonist nor-binaltorphimine dihydrochloride (nor-BNI) dose-dependently prevented ABA renewal of fear, but had no effect on the expression of ABC renewal, the expression of extinction, or the expression of nonextinguished fear. Conversely, pretest infusion of the KOR agonist U50,488 hydrochloride (U50,488) selectively facilitated the expression of ABA renewal and had no effect on the expression of extinction. Pretest infusion of nor-BNI had no effect on the expression of context-specific latent inhibition. Collectively, these results suggest that KORs gate the expression of fear following extinction training and may comprise a critical neuropeptide component of the circuitry underlying context-dependent expression of fear.     

Return of fear in a human differential conditioning paradigm caused by a stimulus change after extinction

In a human fear conditioning experiment, 32 participants were trained in a differential conditioning procedure with geometrical shapes as CS+ and CS- (four presentations each), and an electric shock as US. Measures of conditioned responding were skin conductance response (SCR) and retrospective US-expectancy ratings. For half of the participants (Generalization Group, GG), the subsequent extinction phase consisted of four nonreinforced presentations of generalization stimuli (GS+ and GS-). Participants from the Extinction control Group received an equal amount of nonreinforced presentations of the CSs. Finally, all participants were tested with the original CSs. The results from both measures clearly show an increase in the size of the discrimination upon the stimulus change after extinction in the GG. Because this pattern is not observed in the Extinction control Group, extinction performance appears to be somehow restricted to the perceptual characteristics of the extinction stimulus. Interestingly, the size of the conditioned SCR discrimination in the GG is not influenced by the stimulus change after acquisition. This observation points to a differential impact of stimulus change after acquisition vs. extinction treatment. The findings are discussed from the theoretical perspective of renewal and the clinical perspective of Return of Fear.     

A developmental dissociation in reinstatement of an extinguished fear response in rats

Recently, studies from our laboratory have shown that 16-day-old rats, in contrast to 23-day-old rats, fail to show either ABA renewal or recovery of an extinguished fear response following a pre-test injection of FG7142 [Kim, J. H. & Richardson, R. (2007). A developmental dissociation of context and GABA effects on extinguished fear in rats. Behavioral Neuroscience; Yap & Richardson, unpublished data]. The present study, using freezing as a measure of learned fear, extends these findings by examining whether there is a developmental difference in susceptibility to reinstatement following extinction. 16- and 23-day-old rats were trained to fear a white-noise conditioned stimulus (CS) by pairing it with a shock unconditioned stimulus (US). This fear was subsequently extinguished by non-reinforced presentations of the CS. Some rats received a post-extinction Reminder which consisted of a single presentation of a reduced-intensity US. Experiments 1 and 2 demonstrated that this Reminder was effective in reinstating extinguished fear in 23-day-olds, and that this reinstatement effect was context-specific in rats this age. In contrast, 16-day-old rats failed to show the reinstatement effect in either experiment. The failure to observe a post-extinction reinstatement effect in the 16-day-olds was not due to a general ineffectiveness of the Reminder treatment at this age because it did alleviate spontaneous forgetting in rats this age (Experiment 3). Taken together, the results suggest that fundamentally different processes may mediate extinction early in development compared to later in development.     

提取-消退范式中复合刺激对恐惧消退的影响

情绪障碍治疗的关键在于消退条件性恐惧记忆,研究证明基于记忆再巩固的提取-消退范式能有效消除或改写原有的恐惧记忆。本研究将提取-消退范式应用到更复杂的恐惧记忆中,采用多感官复合刺激(声音+图片)作为条件刺激,以皮电反应作为恐惧反应指标,考察采用单个线索(声音或图片)、复合线索(声音+图片)进行提取-消退对条件性恐惧记忆的消退效果有何差异。结果表明:声音线索提取-消退组出现了自发恢复和重建效应,图片提取-消退组只出现了重建效应,复合刺激提取-消退组未出现自发恢复和重建效应。说明由复合刺激线索引发的条件性恐惧,采用复合刺激中的单个较强线索或原有完整线索进行提取-消退,对恐惧记忆的消退效果最好。     

Pavlovian Disgust Conditioning and Generalization: Specificity and Associations With Individual Differences

Although studies have identified differences between fear and disgust conditioning, much less is known about the generalization of conditioned disgust. This is an important gap in the literature given that overgeneralization of conditioned disgust to neutral stimuli may have clinical implications. To address this knowledge gap, female participants (n = 80) completed a Pavlovian conditioning procedure in which one neutral food item (conditioned stimulus; CS+) was followed by disgusting videos of individuals vomiting (unconditioned stimulus; US) and another neutral food item (CS–) was not reinforced with the disgusting video. Following this acquisition phase, there was an extinction phase in which both CSs were presented unreinforced. Importantly, participants also evaluated generalization stimuli (GS+, GS?) that resembled, but were distinct from, the CS after each conditioning phase. As predicted, the CS+ was rated as significantly more disgusting and fear inducing than the CS? after acquisition and this pattern persisted after extinction. However, disgust ratings of the CS+ after acquisition were significantly larger than fear ratings. Participants also rated the GS+ as significantly more disgusting, but not fear inducing, than the GS? after acquisition. However, this effect was not observed after extinction. Disgust proneness did predict a greater increase in disgust and fear ratings of the CS+ relative to the CS? after acquisition and extinction. In contrast, trait anxiety predicted only higher fear ratings to the CS+ relative to the CS? after acquisition and extinction. Disgust proneness nor trait anxiety predicted the greater increase in disgust to the GS+ relative to the GS? after acquisition. These findings suggest that while conditioned disgust can generalize, individual difference variables that predict generalization remain unclear. The implications of these findings for disorders of disgust are discussed.     

Fear conditioning in posttraumatic stress disorder: evidence for delayed extinction of autonomic, experiential, and behavioural responses

Aversive conditioning has been proposed as an important factor involved in the etiology of posttraumatic stress disorder (PTSD). However, it is not yet fully understood exactly which learning mechanisms are characteristic for PTSD. PTSD patients (n=36), and healthy individuals with and without trauma exposure (TE group, n=21; nTE group, n=34), underwent a differential fear conditioning experiment consisting of habituation, acquisition, and extinction phases. An electrical stimulus served as the unconditioned stimulus (US), and two neutral pictures as conditioned stimuli (CS+, paired; CS-, unpaired). Conditioned responses were quantified by skin conductance responses (SCRs), subjective ratings of CS valence and US-expectancy, and a behavioural test. In contrast to the nTE group, PTSD patients showed delayed extinction of SCRs to the CS+. Online ratings of valence and US-expectancy as well as the behavioural test confirmed this pattern. These findings point to a deficit in extinction learning and highlight the role of affective valence appraisals and cognitive biases in PTSD. In addition, there was some evidence that a subgroup of PTSD patients had difficulties in learning the CS-US contingency, thereby providing preliminary evidence of reduced discrimination learning.     

Reinstatement of fear in humans: autonomic and experiential responses in a differential conditioning paradigm

The present study investigated reinstatement of fear in humans using an aversive differential conditioning paradigm. Two neutral human face pictures were presented during habituation, acquisition, extinction, and postreinstatement phases. One picture served as a conditioned stimulus (CS) reinforced by an unconditioned stimulus (US) in the form of electrical stimulation (CS+) and the second picture as a control stimulus that was never reinforced (CS-). The prediction that in a reinstatement manipulation a previously extinguished fear response in humans can be reinstated in a reinstatement group by the mere presentation of three unpredicted electrical stimulations (USs) was tested. Participants in the control group were not exposed to unpredicted USs and no reinstatement effect was expected. Outcome measures included subjective US expectancy ratings and skin conductance responses. Results showed non-selective return of the fear response due to fear recovery associated with both CSs (CS+/CS-) in the reinstatement group. Unexpected fear recovery was observed for both CSs (CS+/CS-) in control participants. Results are discussed with respect to context conditioning, fear generalisation, and anxiety-related cognitive mechanisms underlying fear recovery after extinction.     

Temporal specificity of extinction in autoshaping

Three experiments investigated the effects of varying the conditioned stimulus (CS) duration between training and extinction. Ring doves (Streptopelia risoria) were autoshaped on a fixed CS-unconditioned stimulus (US) interval and extinguished with CS presentations that were longer, shorter, or the same as the training duration. During a subsequent test session, the training CS duration was reintroduced. Results suggest that the cessation of responding during an extinction session is controlled by generalization of excitation between the training and extinction CSs and by the number of nonreinforced CS presentations. Transfer of extinction to the training CS is controlled by the similarity between the extinction and training CSs. Extinction learning is temporally specific.     

Conditioned Inhibition Produced by Extinction of a Conditioned Stimulus

Four experiments used a conditioned taste aversion procedure to examine the potential for CS-alone extinction treatment to produce a conditioned stimulus that possesses inhibitory properties. In Experiment 1, saccharin was paired with LiCl, and then saccharin was presented alone for several trials to produce extensive behavioral extinction. Animals receiving this treatment were retarded in reacquiring conditioned responding to saccharin relative to control subjects receiving conditioning to the flavor for the first time. In Experiment 2, the extinguished saccharin stimulus was shown to decrease conditioned responding to a known excitor when the two stimuli were presented in compound as a summation test. Experiments 3A and 3B replicated the findings of Experiments 1 and 2 while providing evidence that the effects were not due to the differential effects of neophobia during testing. These three experiments revealed that an extinguished conditioned excitor passes retardation and summation tests for conditioned inhibition. Experiment 4 found that extinction of a known excitor was slowed when the excitor was extinguished in compound with a previously extinguished conditioned stimulus. That is, an extinguished CS provided protection from extinction to another CS, a finding also consistent with the view that extinction produces conditioned inhibition.     

Non-differential return of fear in humans after a reinstatement procedure

The present experiment investigated reinstatement of fear in humans using a differential fear conditioning preparation. In this experiment, one neutral stimulus (conditioned stimulus; CS+) was paired with an aversive stimulus (unconditioned stimulus; US) during the acquisition phase, while another neutral stimulus was not (CS−). This procedure led to a difference in responding between the CS+ and the CS− (i.e., differential conditioning). After this acquisition phase, an extinction phase followed, during which both CSs were presented without the US, resulting in a decrease in differential conditioned responding. Reinstatement refers to the return of extinguished conditioned responses due to the experience of US-only trials after the extinction phase. This phenomenon was investigated by presenting half of the participants (reinstatement group) with unpredictable USs after the extinction phase. The control group did not receive these USs after the extinction procedure. The results show that return of fear was clearly apparent after the reinstating USs. This return of fear was, however, not limited to the CS+. An increase in ‘conditioned’ responding was also observed for the control stimulus. This interesting observation will be discussed against the background of a number of recent theoretical conceptualizations of reinstatement.     

Spontaneous recovery of extinguished fear responses deepens their extinction: a role for error-correction mechanisms

A series of experiments used a within-subject design to study spontaneous recovery of fear responses (freezing) to an extinguished conditioned stimulus (CS) in rats. Experiments 1, 2, 3, and 4 demonstrated that: a remotely extinguished CS elicited more freezing than a recently extinguished one on a common test; that the CS showing recovery underwent greater response loss across additional extinction than the one lacking recovery; and that spontaneous recovery and deepening of response loss survived reconditioning. Experiment 5 demonstrated that an excitor extinguished in compound with a CS showing recovery suffered greater loss than an excitor extinguished in compound with a CS not showing recovery, implying that the differential change is regulated by a common error term. Experiments 6 and 7 demonstrated that extinction of a compound composed of two CSs, one showing recovery and a second lacking recovery, produced greater loss to the CS that showed recovery, implying that the change is also regulated by individual error term.     

Reinstatement of fear to an extinguished conditioned stimulus: two roles for context

The authors studied the role of context in reinstatement. Freezing was reinstated when the conditioned stimulus (CS) was extinguished in 1 context and rats moved to another context for reexposure to the shock unconditioned stimulus (US) and test. It was also reinstated (rather than renewed) when rats were shocked in the extinction context and moved to another context for test. This reinstatement was CS specific and reduced by nonreinforced exposures to the extinction context. Rats shocked in the context in which a stimulus had been preexposed froze when tested in another context. These findings suggest 2 roles for context in reinstatement: conditioning of the test context (M. E. Bouton, 1993) and mediated conditioning by the extinction context (P. C. Holland, 1990).