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.     

EFFECT OF REINFORCEMENT PROBABILITY AND PRIZE SIZE ON COCAINE AND HEROIN ABSTINENCE IN PRIZE‐BASED CONTINGENCY MANAGEMENT

Although treatment outcome in prize‐based contingency management has been shown to depend on reinforcement schedule, the optimal schedule is still unknown. Therefore, we conducted a retrospective analysis of data from a randomized clinical trial (Ghitza et al., 2007) to determine the effects of the probability of winning a prize (low vs. high) and the size of the prize won (small, large, or jumbo) on likelihood of abstinence until the next urine‐collection day for heroin and cocaine users (N = 116) in methadone maintenance. Higher probability of winning, but not the size of individual prizes, was associated with a greater percentage of cocaine‐negative, but not opiate‐negative, urines.     

The emergence of conditioned reinforcement from observation

We report an experiment in which observations of peers by six 3-5-year-old participants under specific conditions functioned to convert a small plastic disc or, for one participant, a small piece of string, from a nonreinforcer to a reinforcer. Prior to the observational procedure, we compared each participant's responding on (a) previously acquired performance tasks in which the child received either a preferred food item or the disc (string) for correct responses, and (b) the acquisition of new repertoires in which the disc (string) was the consequence for correct responses. Verbal corrections followed incorrect responses in the latter tasks. The results showed that discs and strings did not reinforce correct responses in the performance tasks, but the food items did; nor did the discs and strings reinforce correct responses in learning new repertoires. We then introduced the peer observation condition in which participants engaged in a different performance task in the presence of a peer who also performed the task. A partition blocked the participants from seeing the peers' performance. However, participants could observe peers receiving discs or strings. Participants did not receive discs or strings regardless of their performance. Peer observation continued until the participants either requested discs or strings repeatedly, or attempted to take discs or strings from the peers. Following the peer observation condition, the same performance and acquisition tasks in which participants had engaged prior to observation were repeated. The results showed that the discs and strings now reinforced correct responding for both performance and acquisition for all participants. We discuss the results with reference to research involving nonhuman subjects that demonstrated the observational conditioning of reinforcers.     

When two paradigms meet: Does evaluative learning extinguish in differential fear conditioning?

Contemporary theories of Pavlovian conditioning propose a distinction between signal learning (SL), in which a conditioned stimulus (CS) becomes a predictor for a biologically significant unconditioned stimulus (US), and evaluative learning (EL), in which the valence of the US is transferred to the CS. This distinction is based largely on the different susceptibilities of EL and SL to extinction. This study compared the extinction of indices of EL (online valence ratings) and SL (US-expectancy ratings and skin conductance responses, SCRs) in a differential fear conditioning design using complex CSs. Only half of the participants gave online valence ratings, allowing us to confirm that online valence measurement did not influence SCRs. In line with the distinction between EL and SL, SCRs extinguished rapidly while valence ratings showed resistance to extinction. US-expectancy ratings, however, were not distinguishable from valence ratings indicating that verbal indicators of EL and SL share a similar time course.     

Learning in cod (Gadus morhua): long trace interval retention

Basic knowledge about learning capacities and awareness in fish is lacking. In this study we investigated which temporal gaps Atlantic cod could tolerate between two associated events, using an appetitive trace-conditioning paradigm with blinking light as conditioned stimulus (CS) and dry fish food as unconditioned stimulus (US). CS–US presentations were either temporally overlapping (delay conditioning, CS duration 24 s, interstimulus interval 12 s) or separated by 20, 60, or 120 s (trace conditioning, CS duration 12 s) or 2 h (control, CS duration 12 s). The percentage of fish in the feeding area increased strongly during CS presentation in all delay, 20 s, and 60 s trace groups and in one out of two 120 s trace groups, but not in the control groups. In the 20 and 60 s trace procedures, the fish crowded together in the small feeding area during the trace interval, showing strong anticipatory behaviour. In all the conditioned groups, the fish responded to the CS within eight trials, demonstrating rapid learning. At 88 and 70 days after the end of the conditioning experiments, the delay and 20 s trace groups, respectively, were presented the CS six times at 2-h intervals without reward. All groups responded to the light signal, demonstrating memory retention after at least 3 months. This study demonstrates that Atlantic cod has an impressively good ability to associate two time-separated events and long time retention of learnt associations.     

Social learning theory and cognitive behavioral models of body dysmorphic disorder

Contemporary cognitive behavioral models of body dysmorphic disorder are reviewed, whereby the first by Neziroglu and colleagues emphasizes conditioning processes and relational frame theory and the latter by Veale emphasizes information processing. A brief review of the existing cognitive behavioral therapy research follows the presentation of the models. The majority of publications on BDD continue to deal with phenomenology and epidemiology, and much more research on cognitive behavioral treatment is needed. Treatment research should be geared towards testing elements of the models explicated in this article, and randomized controlled trials are greatly needed.     

Activation of amygdaloid PKC pathway is necessary for conditioned cues-provoked cocaine memory performance

Drug-associated cues are critical in reinstating the drug taking behavior even during prolonged abstinence and thus are thought to be a key factor to induce drug craving and to cause relapse. Amygdaloid complex has been known for its physiological function in mediating emotional experience storage and emotional cues-regulated memory retrieval. This study was undertaken to examine the role of basolateral nuclei of amygdala and the intracellular signaling molecule in drug cues-elicited cocaine memory retrieval. Systemic anisomycin treatment prior to the retrieval test abolished the cues-provoked cocaine conditioned place preference (CPP) memory. Likewise, a similar blockade of cues-provoked cocaine CPP performance was achieved by infusion of anisomycin and cycloheximide into the basolateral nuclei of amygdala before the test. Intra-amygdaloid infusion of H89, a protein kinase A inhibitor, or U0126, a MEK inhibitor, did not affect retrieval of the cues-elicited cocaine CPP memory. In contrast, intra-amygdaloid infusion of NPC 15437, a PKC inhibitor, abolished the cues-elicited cocaine CPP expression, while left the memory per se intact. Intra-amygdaloid infusion of NPC 15437 did not seem to affect locomotor activity or exert observable aversive effect. Taken together, our results suggest that activation of PKC signaling pathway and probably downstream de novo protein synthesis in the basolateral nuclei of amygdala is required for the cues-elicited cocaine memory performance. However, temporary inhibition of this signaling pathway does not seem to affect cocaine CPP memory per se.     

Auditory specific fear conditioning results in increased levels of synaptophysin in the basolateral amygdala

Auditory fear conditioning is one of the most well characterized models used in studies of learning and memory. In order to ensure the animals have been conditioned to fear the auditory stimulus, animals are generally tested for their response to this stimulus in a different context to that used for training. For this reason it is often unclear how much contextual fear conditioning the animals also acquire when they are trained. In this study, we have established a protocol for fear conditioning in mice which is explicit for auditory cues; mice trained using this protocol, show a very low fear response to contextual cues encountered during training. We have undertaken analysis to look for potential brain changes associated with this model by measuring levels of the synaptic vesicle protein, synaptophysin, in the basolateral nuclei of the amygdala following auditory fear conditioning. Our results show levels of synaptophysin were significantly higher in mice which learnt to associate the auditory stimulus with fear, in comparison to all non-learning control animals. These findings support the idea that synaptic plasticity associated with formation of fear conditioning to a single specific conditioned stimulus occurs within the basolateral nuclei of the amygdala. Furthermore, our results demonstrate the usefulness of this model in looking for changes in the brain specific for a defined learning event.     

Socially mediated learning in male Betta splendens. III: Rapid acquisitions

In four experiments with male Siamese fighting fish, the classical conditioning of visual/spatial cues with elicitors of aggression was demonstrated. These studies show that this type of socially mediated learning is more rapidly conditioned than was previously known. One 15-min training session is adequate to condition a preference for those cues that had recently been paired with conspecific images. Finally, behavior occurring during acquisition, in the presence of aggression-eliciting cues, was uncorrelated with the magnitude of the learned preferences that were assayed during extinction tests and in the absence of social stimuli.     

Affective-Evaluative Learning in Humans: A Form of Associative Learning or Only an Artifact?

The status of evaluative conditioning (EC) as a distinct form of associative learning was called in question by Field and Davey (1997, 1998, 1999), who argued that in the typical visual EC paradigm, nonassociative visual concept learning is responsible for the evaluative changes observed. Especially, the use of only within-subject control conditions instead of independent control groups was criticized. The present three experiments show (a) that EC effects can be demonstrated within another sensory modality than visual perception and (b) that EC effects are demonstrable in a between-subject design (including a successful replication attempt). A further result was that these EC effects do not require participants' conscious awareness. The data provide no support for an artifactual account of EC but suggest an interpretation of EC as a form of associative learning.