Gonzalo Miguez

Classical conditioning and pain: Conditioned analgesia and hyperalgesia

This article reviews situations in which stimuli produce an increase or a decrease in nociceptive responses through basic associative processes and provides an associative account of such changes. Specifically, the literature suggests that cues associated with stress can produce conditioned analgesia or conditioned hyperalgesia, depending on the properties of the conditioned stimulus (e.g., contextual cues and audiovisual cues vs. gustatory and olfactory cues, respectively) and the proprieties of the unconditioned stimulus (e.g., appetitive, aversive, or analgesic, respectively). When such cues are associated with reducers of exogenous pain (e.g., opiates), they typically increase sensitivity to pain. Overall, the evidence concerning conditioned stress-induced analgesia, conditioned hyperalagesia, conditioned tolerance to morphine, and conditioned reduction of morphine analgesia suggests that selective associations between stimuli underlie changes in pain sensitivity.

Using context to resolve temporal ambiguity.

Three conditioned lick suppression experiments with rats examined the role of the context in the selection and integration of independently acquired interval relationships. In Experiment 1, rats were exposed to separate conditioned stimuli 1 and 2 (CS1-CS2) pairings with 2 different interval relationships, each in its own distinctive context, X or Y. The resultant integration was determined by the training context (X or Y) in which unconditioned stimulus (US)-CS2 backward pairings occurred, as assessed in a third neutral context (Z). In Experiment 2, rats experienced CS1-CS2 pairings with 2 different interval relationships as in Experiment 1, and then received US-CS2 pairings in both contexts X and Y. The testing context (i.e., X or Y) determined the resultant integration. In Experiment 3, rats were exposed to CS1-CS2 pairings in 2 different interval relationships each in different phases (i.e., Phases 1 and 2), and then in Phase 3 received US-CS2 pairings. The temporal context of testing (i.e., short or long retention interval) determined the resultant integration. Thus, both physical and temporal context can be used to disambiguate conflicting temporal information.

When does integration of independently acquired temporal relationships take place

Prior research has found that when subjects independently acquire 2 associations with a common element (e.g., S1-S2 and S2-US), each with its own temporal relationship, they behave as if the 2 unique cues (i.e., S1 and US) have a known temporal relationship despite their never having been paired. This is interpreted as indicative of temporal integration of the memories acquired during Phase 1 and Phase 2 of training based on the element common to both experiences (i.e., S2). There are 2 times at which such integration of independent temporal relationships could plausibly occur: at the time of acquisition of the second relationship or at the time of testing. Three lick-suppression experiments with rats were performed to determine when integration occurs. This question of the moment of temporal integration was assessed by extinguishing the mediating element (S2) between learning of the second temporal relationship and testing of S1. Experiment 1 (using sensory preconditioning) and Experiment 2 (using second-order conditioning) found that this manipulation interfered with behavioral control by S1, suggesting that temporal integration occurred at the time of testing. Experiment 3 used spontaneous recovery, a hallmark phenomenon of extinction, to confirm that the S2-alone presentations in Experiments 1 and 2 attenuated integration as a result of extinction of S2. Implications for the temporal coding hypothesis (e.g., Savastano & Miller, 1998) are discussed.

Trial spacing during extinction: the role of context-US associations.

Studies of extinction in Pavlovian preparations can identify conditions that make extinction more enduring and increase the benefits of exposure-based behavior therapy. One such potential condition is the use of spaced extinction trials. Nevertheless, contradictory results of spacing extinction trials are found in the existing literature. Here we examine the strength of the association between the extinction context and the unconditioned stimulus as a variable that reconciles the seemingly contradictory prior reports. To assess the role of this variable, we evaluated the effects of extinction trial spacing as a function of the associative status of the extinction context in three lick suppression experiments with rats. In Experiment 1, the associative status of the extinction context was manipulated by giving extinction treatment in either the same context as acquisition or a different context. In Experiment 2, the associative status of the extinction context was initially high as a result of the acquisition context being used for extinction and then it was manipulated through postacquisition context exposure. In Experiment 3, extinction was administered in a context different from that of acquisition and the associative status of the extinction context was manipulated by delivering unsignaled footshock (i.e., the unconditioned stimuli) in the extinction context between acquisition and extinction. In all three experiments, consistently less conditioned suppression was observed with spaced extinction trials relative to massed extinction trials when the associative value of the extinction context was relatively low. In contrast, massed extinction trials produced less conditioned suppression when the associative status of the extinction context was high. Thus, stimulus control after extinction is influenced by an interaction between the intertrial interval during extinction and the associative status of the extinction context.

The role of contextual associations in producing the partial reinforcement acquisition deficit

Three conditioned suppression experiments with rats as subjects assessed the contributions of the conditioned stimulus (CS)-context and context-unconditioned stimulus (US) associations to the degraded stimulus control by the CS that is observed following partial reinforcement relative to continuous reinforcement training. In Experiment 1, posttraining associative deflation (i.e., extinction) of the training context after partial reinforcement restored responding to a level comparable to the one produced by continuous reinforcement. In Experiment 2, posttraining associative inflation of the context (achieved by administering unsignaled outcome presentations in the context) enhanced the detrimental effect of partial reinforcement. Experiment 3 found that the training context must be an effective competitor to produce the partial reinforcement acquisition deficit. When the context was down-modulated, the target regained behavioral control thereby demonstrating higher-order retrospective revaluation. The results are discussed in terms of retrospective revaluation, and are used to contrast the predictions of a performance-focused model with those of an acquisition-focused model.

Animal models of psychopathology: Historical models and the pavlovian contribution

La investigacion con animales no humanos como sujetos experimentales, para entender el comportamiento humano, se basa en la nocion darwiniana de la continuidad de las especies. En este marco encontramos modelos analogos para entender la biologia y el comportamiento humanos en especies no humanas. En psicologia, los modelos animales han probado ser una herramienta efectiva para el entendimiento del comportamiento humano, tanto normal como anormal. En la presente revision discutimos como los modelos animales han sido usados al investigar la psicopatologia. Luego de revisar tres modelos animales historicos de psicopatologias especificas, discutimos como los fenomenos descubiertos al estudiar el condicionamiento pavloviano han contribuido a nuestra comprension de la etiologia y mantencion de la psicopatologia humana, como la tradicion pavloviana ha contribuido al desarrollo de mejores formas de tratamiento para desordenes del comportamiento, y de forma mas general, como los fenomenos pavlovianos se encuentran implicados en casi todas las interacciones entre un organismo y su ambiente.

Spontaneous recovery and ABC renewal from retroactive cue interference

Two conditioned suppression experiments with rats were conducted to determine whether the spontaneous recovery and renewal that are commonly observed in retroactive outcome interference (e.g., extinction) also occur in retroactive cue interference. Experiment 1 showed that a long delay between Phase 2 (the interfering phase) and testing produces a recovery from the cue interference (i.e., the delay enhanced responding to the target cue trained in Phase 1), which is analogous to the spontaneous recovery effect observed in extinction and other retroactive outcome interference procedures. Experiment 2 showed that, when target and interfering cues are trained in separate contexts and testing occurs in a different but familiar context, a recovery from the cue interference is also observed (i.e., the context shift enhanced responding to the target), which is analogous to ABC renewal from extinction. The results are discussed in terms of the possibility that similar associative mechanisms underlie cue and outcome interference.

Comparing the context specificity of extinction and latent inhibition

Exposure to a cue alone either before (i.e., latent inhibition treatment) or after (i.e., extinction) the cue is paired with an unconditioned stimulus results in attenuated conditioned responding to the cue. Here we report two experiments in which potential parallels between the context specificity of the effects of extinction and latent inhibition treatments were directly compared in a lick suppression preparation with rats. The reversed ordering of conditioning and nonreinforcement in extinction and latent inhibition designs allowed us to examine the effect of training order on the context specificity of what is learned given phasic reinforcement and nonreinforcement of a target cue. Experiment 1 revealed that when conditioned-stimulus (CS) conditioning and CS nonreinforcement were administered in the same context, both extinction and latent inhibition treatments had reduced impacts on test performance, relative to excitatory conditioning when testing occurred outside the treatment context. Similarly, Experiment 2 showed that when conditioning was administered in one context and nonreinforcement was administered in a second context, the effects of both extinction and latent inhibition treatments were attenuated when testing occurred in a neutral context, relative to the context in which the CS was nonreinforced. The observed context specificity of extinction and latent inhibition treatments has been previously reported in both cases, but not in a single experiment under otherwise identical conditions. The results of the two experiments convergently suggest that memory of nonreinforcement becomes context dependent after a cue is both reinforced and nonreinforced, independent of the order of training.

Extinction with multiple excitors

Four conditioned suppression experiments with rats, using an ABC renewal design, investigated the effects of compounding the target conditioned excitor with additional, nontarget conditioned excitors during extinction. Experiment 1 showed stronger extinction, as evidenced by less renewal, when the target excitor was extinguished in compound with a second excitor, relative to when it was extinguished with associatively neutral stimuli. Critically, this deepened extinction effect was attenuated (i.e., more renewal occurred) when a third excitor was added during extinction training. This novel demonstration contradicts the predictions of associative learning models based on total error reduction, but it is explicable in terms of a counteraction effect within the framework of the extended comparator hypothesis. The attenuated deepened extinction effect was replicated in Experiments 2a and 3, which also showed that pretraining consisting of weakening the association between the two additional excitors (Experiments 2a and 2b) or weakening the association between one of the additional excitors and the unconditioned stimulus (Experiment 3) attenuated the counteraction effect, thereby resulting in a decrease in responding to the target excitor. These results suggest that more than simple total error reduction determines responding after extinction.

Failure to observe renewal following retrieval-induced forgetting.

Recent studies have pursued the nature of inhibition observed in retrieval-induced forgetting (RIF) tasks. In a RIF paradigm, participants are trained on category-exemplar pairs in Phase 1. Then, some exemplars from select categories (Rp+ items) receive further practice in Phase 2. At test, impaired recall for non-practiced exemplars of the practiced categories (Rp- items) is observed relative to exemplars from non-practiced categories (Nrp items). This difference constitutes RIF. Prior reports of spontaneous recovery from RIF indicate that RIF represents a lapse rather than a loss of memory. Empirical analogs and theoretical considerations suggest that RIF should also be reversible through a change of context between Phase 2 and testing (i.e., renewal). We conducted two experiments using human participants to evaluate the context dependency of RIF. In both experiments, Phases 1 and 2 occurred in distinctly different contexts with subsequent testing occurring in either the Phase 1 context or the Phase 2 context. RIF was observed in both experiments. Experiment 1 additionally found that the magnitude of RIF was not reduced by testing in the Phase 1 context relative to testing in the Phase 2 context. Experiment 2 further tested context dependency of RIF by (1) increasing the dissimilarity between the two contexts and (2) inserting a retention interval between Phase 2 and test for half of the participants in each test context condition. The data again indicated no effect of the context manipulation. Thus, no renewal from RIF was observed in either experiment; moreover, these null findings were supported by Bayesian analyses. These results are compared with analogous inhibitory processes in the animal memory literature that typically show both physical and temporal context dependency.