Extinction Context Research Articles

Renewal of threat expectancy in an online contextual avoidance paradigm

Extinction of fear and avoidance is not permanent and can return following contextual changes (termed renewal). The aim of the current study was to investigate the renewal of avoidance, threat expectancy, and fear ratings in an online avoidance task administered during the COVID-19 pandemic. One-hundred and two participants completed a task consisting of habituation, threat conditioning, avoidance conditioning, extinction with response prevention, and renewal. Tests for renewal occurred either in the original conditioning context (ABA, n = 52) or the extinction context (ABB, n = 50). Images of a quiet and a busy street served as relevant contexts. Renewal was evident whereby the ABA group showed a significant increase in threat expectancy when tested in the conditioning context, which had not been extinguished. This effect was not found for avoidance or fear ratings, nor for the ABB group who underwent the renewal test in the extinction context. The current study demonstrated differential renewal of threat expectancy in an online contextual avoidance paradigm.

Sex Differences in Contextual Extinction Learning After Single Binge-Like EtOH Exposure in Adolescent C57BL/6J Mice.

This study investigates the impact of binge-like alcohol exposure on context extinction learning, aiming to identify previously unrecognized risks associated with this common drinking pattern and the development of trauma- and stress-related disorders, such as PTSD. Our findings reveal that binge-like alcohol exposure impairs extinction learning in male adolescent mice by disrupting molecular mechanisms within fear memory circuits, suggesting novel therapeutic and preventive targets. Dysregulated candidates include the canonical Wnt/β-catenin signaling proteins, β-catenin and GSK-3β, along with FKBP5, a key player in glucocorticoid signaling and part of a gene network linked to PTSD. These alterations, found in the dorsal hippocampus (dHPC), basolateral amygdala (BLA), striatum, and nucleus accumbens (NAc) core and shell, may serve as promising targets for future pharmacological intervention.

Renewal of conditioned fear in male and female rats.

Pavlovian extinction reduces the performance of conditioned responses and occurs when the conditioned stimulus (CS) is repeatedly presented in the absence of the unconditioned stimulus (US). However, when the CS is experienced in a context that is different from the extinction context, there is a recovery of the conditioned response, a phenomenon known as renewal. There is some evidence that the renewal of appetitive conditioning is influenced by sex, with females failing to exhibit renewed responding. Further, there is recent evidence that renewal of fear might also not occur in female rats. In both appetitive and fear preparations, the lack of renewal in females has been postulated to be related to cycling ovarian hormones. Therefore, in Experiments 1 and 2, we directly compared fear renewal in males and females (Experiment 1) as well as ovariectomized (OVX) females (Experiment 2) when conditioning occurred in Context A, extinction in B, and testing in A (ABA renewal). Experiments 3 and 4 examined renewal when conditioning and extinction occurred in A and testing occurred in B (AAB renewal). In all experiments, renewal was not significantly different between male and female rats. Further, in Experiments 2 and 4, renewal did not differ between males, intact females, and OVX females. Additionally, in each experiment, there was no evidence that context excitation and/or inhibition contributed to renewal; instead suggesting that renewal was controlled by an occasion-setting mechanism. Overall, these results suggest little evidence for the role of sex in renewal of conditioned freezing and also indicate that cycling ovarian hormones have little role in the strength of renewal in female rats. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

ABA and AAB renewal of alcohol seeking in rats are reduced by exposure to beer before extinction

Three experiments with rats examined the impact of a retrieval-extinction procedure on ABA and AAB renewal of instrumental learning. In all experiments, rats were trained to run down an alley for alcoholic beer in Context A. Then, the instrumental response underwent extinction, which was conducted in Context B for Experiments 1 and 2, and in Context A for Experiment 3. In each experiment, one group of animals received a brief exposure to the beer prior to each extinction session, whereas this beer exposure was omitted for a second group. Moreover, Experiment 2 comprised a third group that was exposed to non-alcoholic beer before each extinction session. Finally, all rats were tested in their extinction context and in a second context, which was Context A for Experiments 1 and 2, and Context B for Experiment 3. We found ABA (Experiments 1 and 2) and AAB (Experiment 3) renewal of beer seeking in those animals for which beer exposure prior to extinction was omitted. However, response recovery was not evident when animals received exposure to beer before extinction, regardless of whether alcoholic or non-alcoholic beer was used. Our results suggest that the renewal of alcohol seeking can be prevented by means of the retrieval-extinction paradigm.

Signalling unpaired unconditional stimuli during extinction does not impair their effect to reduce renewal of conditional fear

Presenting unpaired unconditional stimuli (US) during extinction training reduces the renewal of conditional fear due to context change and slows re-acquisition. The present study investigated whether this reduced return of fear is mediated by Pavlovian inhibitory conditioning to the conditional stimulus paired with the US during acquisition (CS+) that is acquired when this stimulus is presented without the US in an excitatory extinction context. Using an ABA renewal paradigm that trained extinction in a context different from acquisition and renewal test, participants either received no USs (Standard), five unsignalled US presentations (Unsignalled) or five presentations of the US preceded by a novel, third CS (Signalled) during extinction training. Extinction was followed by tests for renewal and re-acquisition. Replicating previous results, renewal of electrodermal conditional responses was observed in group Standard, but not in group Unsignalled. Signalling the additional USs, and thus reducing context conditioning and the potential for inhibitory conditioning, did not reduce their effect in that renewal was absent in group Signalled. These results are inconsistent with an inhibitory conditioning account of the effects of unpaired US presentations during extinction. A trial sequence learning account or an arousal account may explain the effects of unpaired presentations of the US during extinction.

Renewal of instrumental avoidance in humans.

The ABA renewal effect occurs when behavior is trained in one context (A), extinguished in a second context (B), and the test occurs in the training context (A). Two mechanisms that explain ABA renewal are context summation at the test and contextual modulation of extinction learning, with the former being unlikely if both contexts have a similar associative history. In two experiments, we used within-subjects designs in which participants learned to avoid a loud noise (unconditioned stimulus) signaled by discrete visual stimuli (conditioned stimuli [CSs]), by pressing the space bar on the computer keyboard. The training was conducted in two contexts, with a different pair of CSs (CS+ and CS-) trained in each context. During extinction, CS+ and CS- stimuli were presented in the alternative context from that of training, and participants were allowed to freely respond, but no loud noise was presented. Finally, all CSs were tested in both contexts, resulting in a within-subjects ABA versus ABB comparison. Across experiments, participants increased avoidance responses during training and decreased them during extinction, although Experiment 2 revealed less extinction. During the test, responding was higher when CS+ were tested in the training context (ABA) versus the extinction context (ABB), revealing the renewal of instrumental avoidance. Experiment 2 also measured expectancy after the avoidance test and revealed a remarkable similarity between avoidance responses and expectancy ratings. This study shows the renewal of instrumental avoidance in humans, and the results suggest the operation of a modulatory role for the context in renewal, similar to the occasion setting of extinction learning by the context. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Ventral hippocampus mediates inter-trial responding in signaled active avoidance

The hippocampus has a central role in regulating contextual processes in memory. We have shown that pharmacological inactivation of ventral hippocampus (VH) attenuates the context-dependence of signaled active avoidance (SAA) in rats. Here, we explore whether the VH mediates intertrial responses (ITRs), which are putative unreinforced avoidance responses that occur between trials. First, we examined whether VH inactivation would affect ITRs. Male rats underwent SAA training and subsequently received intra-VH infusions of saline or muscimol before retrieval tests in the training context. Rats that received muscimol performed significantly fewer ITRs, but equivalent avoidance responses, compared to controls. Next, we asked whether chemogenetic VH activation would increase ITR vigor. In male and female rats expressing excitatory (hM3Dq) DREADDs, systemic CNO administration produced a robust ITR increase that was not due to nonspecific locomotor effects. Then, we examined whether chemogenetic VH activation potentiated ITRs in an alternate (non-training) test context and found it did. Finally, to determine if context-US associations mediate ITRs, we exposed rats to the training context for three days after SAA training to extinguish the context. Rats submitted to context extinction did not show a reliable decrease in ITRs during a retrieval test, suggesting that context-US associations are not responsible for ITRs. Collectively, these results reveal an important role for the VH in context-dependent ITRs during SAA. Further work is required to explore the neural circuits and associative basis for these responses, which may be underlie pathological avoidance that occurs in humans after threat has passed.

Pharmacological manipulations of the dorsomedial and dorsolateral striatum during fear extinction reveal opposing roles in fear renewal

Systemic manipulations that enhance dopamine (DA) transmission around the time of fear extinction can strengthen fear extinction and reduce conditioned fear relapse. Prior studies investigating the brain regions where DA augments fear extinction focus on targets of mesolimbic and mesocortical DA systems originating in the ventral tegmental area, given the role of these DA neurons in prediction error. The dorsal striatum (DS), a primary target of the nigrostriatal DA system originating in the substantia nigra (SN), is implicated in behaviors beyond its canonical role in movement, such as reward and punishment, goal-directed action, and stimulus–response associations, but whether DS DA contributes to fear extinction is unknown. We have observed that chemogenetic stimulation of SN DA neurons during fear extinction prevents the return of fear in contexts different from the extinction context, a form of relapse called renewal. This effect of SN DA stimulation is mimicked by a DA D1 receptor (D1R) agonist injected into the DS, thus implicating DS DA in fear extinction. Different DS subregions subserve unique functions of the DS, but it is unclear where in the DS D1R agonist acts during fear extinction to reduce renewal. Furthermore, although fear extinction increases neural activity in DS subregions, whether neural activity in DS subregions is causally involved in fear extinction is unknown. To explore the role of DS subregions in fear extinction, adult, male Long-Evans rats received microinjections of either the D1R agonist SKF38393 or a cocktail consisting of GABAA/GABAB receptor agonists muscimol/baclofen selectively into either dorsomedial (DMS) or dorsolateral (DLS) DS subregions immediately prior to fear extinction, and extinction retention and renewal were subsequently assessed drug-free. While increasing D1R signaling in the DMS during fear extinction did not impact fear extinction retention or renewal, DMS inactivation reduced later renewal. In contrast, DLS inactivation had no effect on fear extinction retention or renewal but increasing D1R signaling in the DLS during extinction reduced fear renewal. These data suggest that DMS and DLS activity during fear extinction can have opposing effects on later fear renewal, with the DMS promoting renewal and the DLS opposing renewal. Mechanisms through which the DS could influence the contextual gating of fear extinction are discussed.

Dissimilarities of neural representations of extinction trials are associated with extinction learning performance and renewal level.

Renewal of extinguished responses is associated with higher activity in specific extinction-relevant brain regions, i.e., hippocampus (HC), inferior frontal gyrus (IFG), and ventromedial PFC (vmPFC). HC is involved in processing of context information, while IFG and vmPFC use such context information for selecting and deciding among competing response options. However, it is as yet unknown to what extent trials with changed versus unchanged outcome, or extinction trials that evoke renewal (i.e., extinction context differs from acquisition and test context: ABA trials) and trials that do not (i.e., same context in all phases: AAA trials) are represented differentially in extinction-relevant brain regions. In this study, we applied representational similarity analysis (RSA) to determine differences in neural representations of these trial types and their relationship to extinction error rates and renewal level. Overall, individuals with renewal (REN) and those without (NoREN) did not differ significantly in their discrimination levels between ABA and AAA extinction trials, with the exception of right posterior HC, where REN exhibited more pronounced context-related discrimination. In addition, higher dissimilarity of representations in bilateral posterior HC, as well as in several IFG regions, during extinction learning was linked to lower ABA renewal rates. Both REN and NoREN benefitted from prediction error feedback from ABA extinction errors for context- and outcome-related discrimination of trials in IFG, vmPFC, and HC, but only the NoREN group also benefitted from error feedback from AAA extinction errors. Thus, while in both groups the presence of a novel context supported formation of distinct representations, only in NoREN the expectancy violation of the surprising change of outcome alone had a similar effect. In addition, only in NoREN context-related discrimination was linked to error feedback in vmPFC. In summary, the findings show that context- and outcome-related discrimination of trials in HC, vmPFC, and IFG is linked to extinction learning errors, regardless of renewal propensity, and at the same time point towards differential context processing strategies in REN and NoREN. Moreover, better discrimination of context-related trials during extinction learning promotes less renewal during extinction recall, suggesting that renewal may be related to suboptimal context-related trial discrimination.

Glutamatergic neurons in ventral pallidum modulate heroin addiction via epithalamic innervation in rats.

Glutamatergic neurons in ventral pallidum (VPGlu) were recently reported to mediate motivational and emotional behavior, but its role in opioid addiction still remains to be elucidated. In this study we investigated the function of VPGlu in the context-dependent heroin taking and seeking behavior in male rats under the ABA renewal paradigm. By use of cell-type-specific fiber photometry, we showed that the calcium activity of VPGlu were inhibited during heroin self-administration and context-induced relapse, but activated after extinction in a new context. The drug seeking behavior was accompanied by the decreased calcium signal of VPGlu. Chemogenetic manipulation of VPGlu bidirectionally regulated heroin taking and seeking behavior. Anterograde tracing showed that the lateral habenula, one of the epithalamic structures, was the major output region of VPGlu, and its neuronal activity was consistent with VPGlu in different phases of heroin addiction and contributed to the motivation for heroin. VPGlu axon terminals in LHb exhibited dynamic activity in different phases of heroin addiction. Activation of VPGlu-LHb circuit reduced heroin seeking behavior during context-induced relapse. Furthermore, the balance of excitation/inhibition from VP to LHb was shifted to enhanced glutamate transmission after extinction of heroin seeking motivation. Overall, the present study demonstrated that the activity of VPGlu was involved in the regulation of heroin addiction and identified the VPGlu-LHb pathway as a potential intervention to reduce heroin seeking motivation.

Increased Generalization, Stronger Acquisition, or Reduced Extinction? Investigation of the Mechanisms Underlying the Acquisition-in-Multiple-Contexts Effect

Prior research has demonstrated that conducting acquisition in multiple contexts results in more responding to the point that it can even nullify the benefit of subsequent extinction in multiple contexts on reducing renewal of excitatory responding. The underlying mechanism to explain why this happens has not been systematically examined. Using self-reported expectancy of the outcome, the current study investigates three mechanisms that potentially explain why acquisition in multiple contexts results in more responding—greater generalization, stronger acquisition learning, or slower extinction learning. Participants (N = 180) received discriminative training with a conditioned stimulus (CS+) and outcome pairing and a CS− → noOutcome pairing in either one or three contexts. This was followed by either extinction treatment in a novel context or no extinction. Finally, testing occurred in the acquisition context, the extinction context, or a novel context. Stronger renewal of extinguished conditioned expectation was observed for participants who received CS+ → Outcome pairings in three contexts relative to one context. There was no effect of the number of contexts on the strength of the excitatory CS+ → Outcome association or degree of inhibitory learning that occurred during extinction. This suggests that generalization is the mechanism responsible for the adverse impact to extinction learning when acquisition is conducted in multiple contexts.

In the Beginning Was the Wort: A New Natural Theology of Meaning for Ecological Catastrophe

This paper builds upon a recent corpus of popular science that has elevated previously unsung members of the biosphere—“worts.” It argues that the corpus constitutes a new natural theology, a search for meaning in the biosphere, and suggests a theological underpinning to what its authors intuit: that worts give meaning. To do this, the paper draws on Eduardo Kohn’s How Forests Think (2013) and its examination of meaning as a ubiquitous feature of the multispecies ecosystem. Following on from Kohn, two key arguments are made. First, Kohn’s posthuman anthropology is compatible with a Thomist treatment of organisms in terms of their distinct, life-orientated telos. Second, the current context of potential human extinction puts a life-orientated telos in a new light, reviving the validity of teleological thinking. Sharing the fate of nonhuman subjects, rather than treating them as scientific objects, authors and readers of the new natural theology find meaning among worts.

Cortisol decreases activation in extinction related brain areas resulting in an impaired recall of context-dependent extinction memory

Conditioned responding gradually stops during successful extinction learning. The renewal effect is defined as the recovery of a extinguished conditioned response when the context of extinction is different from acquisition. The stress hormone cortisol is known to have an influence on extinction memory and associative learning. Different effects of cortisol on behaviour and brain activity have been observed with respect to stress timing, duration, and intensity. However, the influence of cortisol prior to the initial encoding of stimulus-outcome associations on extinction learning, renewal and its behavioural and neurobiological correlates is still largely unknown. In our study, 60 human participants received 20 mg cortisol or placebo and then learned, extinguished, and recalled the associations between food stimuli presented in distinct contexts and different outcomes in three subsequent task phases. Learning performance during acquisition and extinction phases was equally good for both treatment groups. In the cortisol group, significantly more participants showed renewal compared to placebo. In the subgroup of participants with renewal, cortisol treated participants showed significantly better extinction learning performance compared to placebo. Participants showing renewal had in general difficulties with recalling extinction memory, but in contrast to placebo, the cortisol group exhibited a context-dependent impairment of extinction memory recall. Imaging analyses revealed that cortisol decreased activation in the hippocampus during acquisition. The cortisol group also showed reduced dorsolateral prefrontal cortex activation when extinction learning took place in a different context, but enhanced activation in inferior frontal gyrus during extinction learning without context change. During recall, cortisol decreased ventromedial prefrontal cortex activation. Taken together, our findings illustrate cortisol as a potent modulator of extinction learning and recall of extinction memory which also promotes renewal.

Neural correlates of context-dependent extinction recall in social anxiety disorder: relevance of intrusions in response to aversive social experiences.

There are phenomenological similarities between social anxiety disorder (SAD) and posttraumatic stress disorder, such as a provoking aversive event, posttraumatic stress symptoms (e.g. intrusions) in response to these events and deficient (context-dependent) fear conditioning processes. This study investigated the neural correlates of context-dependent extinction recall and fear renewal in SAD, specifically in patients with intrusions in response to an etiologically relevant aversive social event. During functional magnetic resonance imaging a two-day context-dependent fear conditioning paradigm was conducted in 54 patients with SAD and 54 healthy controls (HC). This included fear acquisition (context A) and extinction learning (context B) on one day, and extinction recall (context B) as well as fear renewal (contexts C and A) one day later. The main outcome measures were blood oxygen level-dependent responses in regions of interest and skin conductance responses. Patients with SAD showed reduced differential conditioned amygdala activation during extinction recall in the safe extinction context and during fear renewal in the acquisition context compared to HC. Patients with clinically relevant intrusions moreover exhibited hypoactivation of the ventromedial prefrontal cortex (vmPFC) during extinction learning, extinction recall, and fear renewal in a novel context, while amygdala activation more strongly decreased during extinction learning and increased during fear renewal in the acquisition context compared with patients without intrusions. Our study provides first evidence that intrusions in SAD are associated with similar deficits in context-dependent regulation of conditioned fear via the vmPFC as previously demonstrated in posttraumatic stress disorder.

Neurobeachin haploinsufficient mice display sex-independent alterations in cued and contextual fear conditioning.

Neurobeachin ( NBEA ) is a cytoplasmic protein that regulates receptor trafficking, neurotransmitter and hormone secretion, as well as synaptic connectivity. Recently, hippocampus-dependent contextual extinction, the gradual decrease of a conditioned fear response to a context, was suggested to be specifically impaired in male mice with Nbea deficiency ( Nbea+/- ). The current study examines the role of sex in this effect and whether Nbea also influences cued fear conditioning. We included both female and male mice and used a phased contextual and cued fear acquisition protocol that consists of different phases allowing us to assess fear acquisition, cued and contextual fear memory and within-phase extinction. Performance of Nbea+/- mice during assessment of both contextual and cued fear memory was significantly altered compared to controls, independent of sex. Follow-up analyses revealed that this altered performance could be indicative of impaired within-phase extinction. Altered within-phase extinction was not exclusively attributable to hippocampus, and independent of sex. Our results rather suggest that Nbea influences complex learning more broadly across different brain structures.

Estrous cycle state-dependent renewal of appetitive behavior recruits unique patterns of Arc mRNA in female rats.

Renewal is a behavioral phenomenon wherein extinction learning fails to generalize between different contextual environments, thereby representing a significant challenge to extinction-based rehabilitative therapies. Previously, we have shown that renewal of extinguished appetitive behavior differs across the estrous cycle of the female rat. In this experiment that effect is replicated and extended upon to understand how the estrous cycle may modulate contextual representation at the neuronal population level to drive renewal. Estrous cycle stage [i.e., proestrus (P, high hormone) or metestrus/diestrus (M/D, low hormone)] was considered during two important learning and behavioral expression windows: at extinction training and during long-term memory (LTM)/renewal testing. Cellular compartment analysis of temporal activity using fluorescence in situ hybridization (catFISH) for Arc mRNA was conducted after the distinct context-stimulus exposures. Rats in P during context-dependent extinction training but in a different stage of the estrous cycle during LTM and renewal testing (P-different) were shown to exhibit more renewal of conditioned foodcup (but not conditioned orienting) behavior compared to rats in other estrous cycle groups. Importantly, we discovered this depends on the order of tests. P-different rats showed differential Arc mRNA expression in regions of the prefrontal cortex (PFC), amygdala, and hippocampus (HPC). For each case P-different rats had more co-expression (i.e., expression of both nuclear and cytoplasmic) of Arc mRNA compared to other groups; specific to the dorsal HPC, P-different rats also had a more robust Arc mRNA response to the extinction context exposure. These data suggest female rats show estrous cycle state-dependent renewal of appetitive behavior, and differences in context and conditioned stimulus representation at the neuronal level may drive this effect.

Partial reinforcement extinction and omission effects in the elimination and recovery of discriminated operant behavior.

Three experiments explored how training reinforcement schedules and context influence the elimination and recovery of human operant behavior. In Experiment 1, participants learned a discriminated operant response in Context A before the response was eliminated with extinction in Context B. They then received a final test in each context. Groups were trained with a discriminative stimulus that predicted a reinforced response on either every trial (continuous reinforcement [CRF]) or some of the trials (partial reinforcement [PRF]). Extinction was slower following PRF training (a partial reinforcement extinction effect [PREE]) and extinguished responding increased when tested in Context A ("ABA" renewal). Experiment 2 further confirmed the PREE was obtained equally whether extinction occurred in the training context (Context A) or a new context (Context B) which is consistent with trial-based accounts of the PREE. Experiment 3 used the same design as Experiment 1 to evaluate the influence of training reinforcement on response elimination with an omission contingency. Across the omission training phase in Context B, the decrease in responding occurred more slowly in the PRF-trained group in comparison to the CRF-trained group, perhaps the first demonstration of what might be termed a PRF omission effect. Again, ABA renewal was observed in Context A. Training reinforcement schedule therefore had a similar influence on response elimination with extinction and omission. Elimination and recovery of human instrumental behavior, with extinction or omission, are influenced by training reinforcement schedule and context. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Fear extinction relies on ventral hippocampal safety codes shaped by the amygdala.

Extinction memory retrieval is influenced by spatial contextual information that determines responding to conditioned stimuli (CS). However, it is poorly understood whether contextual representations are imbued with emotional values to support memory selection. Here, we performed activity-dependent engram tagging and in vivo single-unit electrophysiological recordings from the ventral hippocampus (vH) while optogenetically manipulating basolateral amygdala (BLA) inputs during the formation of cued fear extinction memory. During fear extinction when CS acquire safety properties, we found that CS-related activity in the vH reactivated during sleep consolidation and was strengthened upon memory retrieval. Moreover, fear extinction memory was facilitated when the extinction context exhibited precise coding of its affective zones. Last, these activity patterns along with the retrieval of the fear extinction memory were dependent on glutamatergic transmission from the BLA during extinction learning. Thus, fear extinction memory relies on the formation of contextual and stimulus safety representations in the vH instructed by the BLA.

The impact of prolonging extinction on the ABC “super renewal” of instrumental responses in rats

Two free operant conditioning experiments with rats examined the impact of conducting a large amount of extinction training on situations that enhance the ABC renewal effect (ABC super renewal). In Experiment 1, ABC renewal was strengthened by conducting acquisition in multiple contexts. All rats were trained to press a lever for food. One group was trained in one context, while the other two groups were trained in three contexts. Then, all rats received extinction in context B. For two groups this phase lasted 4 sessions, whereas it lasted 36 sessions for the other group. In Experiment 2, ABC renewal was strengthened by using a large number of acquisition sessions. Rats were trained to perform an operant response to obtain food in context A. One group received a moderate amount of training, while the rest of the rats received a larger number of acquisition sessions. Responses underwent extinction in context B. Two groups received 4 sessions, while 36 extinction sessions were used for the remaining group. In both experiments, rats were tested in context B (extinction context) and C (renewal context). Greater ABC renewal occurred both when acquisition training was conducted in multiple contexts (Experiment 1) and by increasing the amount of acquisition training (Experiment 2). Nevertheless, we found that conducting a large number of extinction sessions reduced ABC super renewal in Experiment 1 only.

Acute stress persistently alters instrumental motivation without affecting appetitive Pavlovian conditioning, extinction, or contextual renewal

In two experiments, we adapted the stress-enhanced fear learning approach to evaluate the persistent effects of acute stress on appetitive learning and motivation in adult male Long Evans rats. In Experiment 1, we found that exposure to a battery of footshocks in one context had no effect on the acquisition, extinction, or contextual renewal of an appetitive Pavlovian discrimination in different contexts. However, when rats were subsequently trained to respond on a progressive ratio instrumental schedule, rats with a history of shock showed lower response rates and progressive ratio break points. Extinction of the shock-associated context had little effect on progressive ratio responding. In Experiment 2, we replicated this instrumental responding deficit with a continuous reinforcement schedule when the Pavlovian phases did not intervene in the time between shock and instrumental testing. Our findings here demonstrate that highly stressful acute experiences produce long-lasting deficits in instrumental motivation for food in male rats.