Food deprivation enhances both autoshaping and autoshaping impairment by a latent inhibition procedure

Pavlovian learning and conditioned reinforcement

Conditioned reinforcers are widely used in applied behavior analysis. Basic research evidence reveals that Pavlovian learning plays an important role in the acquisition and efficacy of new conditioned-reinforcer functions. Thus, a better understanding of Pavlovian principles holds the promise of improving the efficacy of conditioned reinforcement in applied research and practice. This paper surveys how (and if) Pavlovian principles are presented in behavior-analytic textbooks; imprecisions and knowledge gaps within contemporary Pavlovian empirical findings are highlighted. Thereafter, six practical principles of Pavlovian conditioning are presented along with empirical support and knowledge gaps that should be filled by applied and translational behavior-analytic researchers. Innovative applications of these principles are outlined for research in language acquisition, token reinforcement, and self-control.

Genetics of novelty seeking, amphetamine self-administration and reinstatement using inbred rats

Previous research using outbred rats indicates that individual differences in activity in a novel environment predict sensitivity to the reinforcing effect of psychostimulant drugs. The current study examined if the link between responses related to novelty and amphetamine self-administration is heritable. Twelve inbred rat strains were assessed for locomotor activity in a novel environment, preference for a novel environment, and intravenous amphetamine self-administration (acquisition, extinction and amphetamine-induced reinstatement). Strain differences were observed in activity in a novel environment, novelty preference and amphetamine self-administration, indicating a genetic influence for each of these behaviors. While there was no relation between activity in an inescapable novel environment and amphetamine self-administration, strain-dependent differences in novelty preference were positively correlated with the amount of amphetamine self-administered. There was also a positive correlation between the dose-dependent rate of amphetamine self-administration and magnitude of reinstatement. These results show that the activity in an inescapable novel environment and the preference for a novel environment are different genetically, and thus likely to reflect different behavioral constructs. Moreover, these results implicate a genetic influence on the relation between novelty seeking and stimulant self-administration, as well as on the relation between stimulant reward and reinstatement.

Lever conditioned stimulus-directed autoshaping induced by saccharin-ethanol unconditioned stimulus solution: effects of ethanol concentration and trial spacing

Two experiments were designed to evaluate whether brief access to a saccharin-ethanol solution would function as an effective unconditioned stimulus (US) in Pavlovian-autoshaping procedures. In these experiments, the insertion of a lever conditioned stimulus (CS) was followed by the brief presentation of a sipper tube containing saccharin-ethanol US solution. Experience with this Pavlovian-autoshaping procedure engendered lever CS-directed autoshaping conditioned responses (CRs) in all rats. In Experiment 1, the concentration of ethanol [0%, 2%, 4%, 6%, or 8% (vol./vol.)] in 0.1% saccharin was systematically increased within subjects across autoshaping sessions to evaluate the relation between a rat's drinking and lever pressing. In Experiment 2, the mean intertrial interval (ITI) duration (60, 90, 120 s) was systematically increased within subjects across autoshaping sessions to evaluate the effect of ITI duration on drinking and lever pressing. A pseudoconditioning control group received lever CS randomly with respect to the saccharin-ethanol US solution. In Experiment 1, lever-press autoshaping CRs developed in all rats, and the tendency of a rat to drink an ethanol concentration was predictive of the performance of lever-press autoshaping CRs. In Experiment 2, longer ITIs induced more lever CS-directed responding, and CS-US paired procedures yielded more lever CS-directed responding than that observed in CS-US random procedures. Saccharin-ethanol is an effective US in Pavlovian-autoshaping procedures, inducing more CS-directed responding than in pseudoconditioning controls receiving CS-US random procedures. More lever CS-directed responding was observed when there was more drinking of the saccharin-ethanol US solution (Experiment 1); when the CS and US were paired, rather than random (Experiment 2); and with longer mean ITI durations (Experiment 2). This pattern of results is consistent with the hypothesis that lever CS-directed responding reflects performance of Pavlovian-autoshaping CRs.

The pharmacology of latent inhibition as an animal model of schizophrenia

The nature of the primary symptoms of schizophrenia and our lack of knowledge of its underlying cause both contribute to the difficulty of generating convincing animal models of schizophrenia. A more recent approach to investigating the biological basis of schizophrenia has been to use information processing models of the disease to link psychotic phenomena to their neural basis. Schizophrenics are impaired in a number of experimental cognitive tasks that support this approach, including sensory gating tasks and models of selective attention such as latent inhibition (LI). LI refers to a process in which noncontingent presentation of a stimulus attenuates its ability to enter into subsequent associations, and it has received much attention because it is widely considered to relate to the cognitive abnormalities that characterise acute schizophrenia. Several claims have been made for LI having face and construct validity for schizophrenia. In this review of the pharmacological studies carried out with LI we examine its claim to predictive validity and the role of methodological considerations in drug effects. The data reviewed demonstrate that facilitation of low levels of LI is strongly related to demonstrated antipsychotic activity in man and all major antipsychotic drugs, both typical and atypical, have been shown to potentiate LI using a variety of protocols. Very few compounds without antipsychotic activity are active in this model. In contrast, disruption of LI occurs with a wide range of drugs and the relationship with psychotomimetic potential is less clear. Although reversal of disrupted LI has also been used as a model for antipsychotic acticity, mostly using amphetamine-induced disruption, insufficient studies have been carried out to evaluate its claim to predictive validity. However, like facilitation, it is sensitive to both typical and atypical antipsychotic agents. The data we have reviewed here demonstrate that facilitation of LI and, perhaps to a lesser extent, reversal of disrupted LI fulfil the criteria for predictive validity.

Autoshaping i.v. cocaine self-administration in rats: effects of nondrug alternative reinforcers on acquisition

The purpose of this experiment was to examine the effects of a nondrug alternative reinforcer and feeding conditions on the acquisition of cocaine self-administration. Rats were autoshaped to press a lever that resulted in a 0.2 mg/kg i.v. cocaine infusion. Responses on the lever were monitored during six consecutive autoshaping sessions that occurred each day. A retractable lever was inserted into the operant chamber on a random time 60 s schedule 10 times per session for six sessions that began each hour. Each day the six autoshaping sessions were followed by a 6-h cocaine self-administration session. During self-administration the lever remained extended, and each response on the lever resulted in a cocaine infusion (0.2 mg/kg). The criterion for acquisition of cocaine-reinforced behavior was met when there were 5 consecutive days during which the mean number of infusions during the 6-h self-administration session was at least 100. This procedure was repeated daily until the criterion was met or 30 days elapsed. The rats were also trained to respond on lick-operated automatic drinking devices that delivered 0.05 ml water or a glucose and saccharin solution (G + S) contingent upon each lick response. Five groups of 12-14 rats were compared. The first four groups constituted a 2 x 2 factorial design whereby either G + S or water was available in the home cage for 3 weeks before autoshaping began and G + S or water was available in the operant chamber during autoshaping. These groups were limited to 20 g food per day and all had free access to water.(ABSTRACT TRUNCATED AT 250 WORDS)