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At least 613 records · Page 34Linked to original sources
PubMed2005

The role of CB1 receptors in sweet versus fat reinforcement: effect of CB1 receptor deletion, CB1 receptor antagonism (SR141716A) and CB1 receptor agonism (CP-55940).

It is well established that Cannabis sativa can increase appetite, particularly for sweet and palatable foods. In laboratory animals, cannabinoid CB1 receptor antagonism decreases motivation for palatable foods, and most recently, the CB1 receptor antagonist SR141716A, or rimonabant (Acomplia), was reported to produce weight loss in obese human subjects. Indeed, the endocannabinoid system plays a select role in the rewarding properties of palatable foods, and this is well characterized in laboratory animals with sweet sucrose solutions. In the present study, CB1 knockout mice (CB1 KO) and wild-type littermate mice (WT) were trained to respond for a complex sweet as well as a pure fat reinforcer under a progressive ratio (PR) schedule, to determine whether motivation to consume different palatable foods is tonically regulated by CB1 receptors. To assess sweet reinforcement, several concentrations of the liquid nutritional drink, Ensure, were presented under the PR schedule. For fat reinforcement, several concentrations of corn oil (emulsified in 3% xanthan gum) were made available. Additionally, to compare the result of genetic invalidation of the CB1 receptor to antagonism of the CB1 receptor system, the effect of SR141716A (3.0 mg/kg) on responding for Ensure and corn oil were also assessed using the PR schedule. We also assessed the effect of the CB1 agonist CP-55940 (30 microg/kg) on responding for Ensure and corn oil. CB1 KOs took significantly longer to acquire operant responding maintained by Ensure, and responding for Ensure under the PR schedule was significantly reduced in CB1 KOs as well as in WTs pretreated with SR141716A, as compared to WT controls. Additionally, pretreatment with the CB1 agonist CP-55940 increased responding for Ensure. In contrast, responding for corn oil during acquisition and under the PR schedule was not significantly different in CB1 KOs versus wild-type mice. However, SR141716A did reduce responding for corn oil in WTs, and CP-55940 significantly increased responding for corn oil. Taken together, these results suggest that CB1 receptors are preferentially involved in the reinforcing effects of a complex sweet, as compared to a pure fat, reinforcer. These data also suggest, however, that antagonism of CB1 receptors with SR141716A is sufficient to attenuate the reinforcing effect of Ensure and corn oil, while activation of the central CB1 system is sufficient to enhance Ensure and corn oil reinforcement.

Animals↗
PubMed2006

Resurgence of alcohol seeking produced by discontinuing non-drug reinforcement as an animal model of drug relapse.

Findings from basic behavioral research suggest that simply discontinuing reinforcement for a recently reinforced operant response can cause the recurrence (i.e. resurgence) of a different previously reinforced response. The present experiment examined resurgence as an animal model of drug relapse. Initially, rats pressed levers to self-administer alcohol during baseline conditions. Next, alcohol self-administration was discontinued and non-drug reinforcers (food pellets) were presented contingent on an alternative response (chain pulling). Finally, when the non-drug reinforcer was discontinued, alcohol seeking recurred even though alcohol was still unavailable for lever pressing. These results suggest that simply discontinuing non-drug reinforcement for a behavior may be sufficient to produce relapse to drug seeking. The resurgence procedure could provide a method to examine environmental, pharmacological, and neurobiological factors that lead to relapse following the loss of a non-drug source of reinforcement.

Alcoholism↗
PubMedDate not supplied

Backward inhibitory learning in honeybees: a behavioral analysis of reinforcement processing.

One class of theoretical accounts of associative learning suggests that reinforcers are processed according to learning rules that minimize the predictive error between the expected strength of future reinforcement and its actual strength. The omission of reinforcement in a situation where it is expected leads to inhibitory learning of stimuli indicative for such a violation of the prediction. There are, however, results indicating that inhibitory learning can also be induced by other mechanisms. Here, we present data from olfactory reward conditioning in honeybees that show that (1) one- and multiple-trial backward conditioning results in conditioned inhibition (CI); (2) the inhibition is maximal for a 15-sec interval between US and CS; (3) there is a nonmonotonic dependency on the degree of CI from the US-CS interval during backward pairing; and (4) the prior association of context stimuli with reinforcement is not necessary for the development of CI. These results cannot be explained by models that only minimize a prediction error. Rather, they are consistent with models of associative learning that, in addition, assume that learning depends on the temporal overlap of a CS with two processes, a fast excitatory and a slow inhibitory one, both evoked by a reinforcer. The fmdings from this behavioral analysis of reinforcement processing are compared with the known properties of an individual, identified neuron involved in reinforcement processing in the bee brain, to further understand the mechanisms underlying predictive reward learning.

Animals↗
PubMed2006

Infantile sensitivity to ethanol's motivational effects: Ethanol reinforcement during the third postnatal week.

BACKGROUND: Although tests specific to newborn rats have frequently verified their susceptibility to the reinforcing properties of ethanol, demonstration of comparable reinforcing effects in older infants has been elusive. Using a second-order conditioning procedure, the present study assessed in preweanling rats whether pairing with early postabsorptive effects of ethanol would render intraorally delivered gustatory stimuli capable of positive reinforcement for association with a salient texture. Direct reinforcing effects of ethanol were also evaluated through intake tests of gustatory stimuli previously paired with the drug. Blood ethanol levels (BELs) were determined for each of the ethanol doses used. METHODS: Pups (14 days old) were stimulated with intraoral infusion of sucrose (10% v/v), water, or quinine (0.0045% w/v) 5 minutes after being intragastrically (i.g.) administered 0.00, 0.25, 0.50, or 2.00 g/kg ethanol (Experiments 1 and 2). These stimuli were then briefly presented while pups experienced a rough texture (sandpaper). Rats were subsequently evaluated in a 2-way texture location test (sandpaper vs smooth surface). In Experiment 3, sucrose, water, or quinine was paired with early postabsorptive effects of ethanol (0.00, 0.50, or 2.0 g/kg). Consumption of these stimuli was later assessed. Motor activity patterns during the intake test were also evaluated. In Experiment 4, BELs corresponding to 0.25, 0.50, or 2.0 g/kg ethanol were determined 5 and 20 minutes after i.g. administration (time periods were in accord with the onset and offset of intraoral stimulation used in the previous experiments). RESULTS: Intraoral infusion of sucrose, water, or quinine, while under a state of sobriety and paired with sandpaper, resulted in roughly 50% preference for this texture. Sandpaper preferences were significantly elevated in pups that had experienced sucrose or water in a nonsober state-while under the effects of ethanol (Experiments 1 and 2). This indicated reinforcing effects of the ethanol intoxication. Pairing ethanol intoxication directly with consumption of sucrose, water, or quinine did not affect their later consumption. Yet, there were clear indications that this pairing resulted in conditioned behavioral activity patterns. Blood ethanol levels corresponding to the ethanol doses used here ranged between 10 and 150 mg%. CONCLUSIONS: Infants appear sensitive to pharmacological reinforcing properties of low and relatively high ethanol doses. This sensitivity was revealed indirectly, by pairing gustatory stimuli with ethanol intoxication and then allowing these stimuli to act as second-order reinforcement for a quite different (tactile) stimulus. Behavioral activation elicited by the gustatory stimuli previously paired with a state of intoxication seems to compete with the expression of ethanol's motivational properties as assessed through intake tests.

Animals↗
PubMed2005

Effects of the competitive N-methyl-D-aspartate receptor antagonist, LY235959 [(-)-6-phosphonomethyl-deca-hydroisoquinoline-3-carboxylic acid], on responding for cocaine under both fixed and progressive ratio schedules of reinforcement.

It is difficult to determine the precise role of the N-methyl-D-aspartate (NMDA) receptor system in the reinforcing effects of cocaine since uncompetitive NMDA receptor antagonists alter cocaine self-administration in different ways, depending on the antagonist examined and the behavior being measured. To increase understanding of the role of the NMDA system in cocaine's reinforcing effects, this study measured the effects of the competitive NMDA receptor antagonist, LY235959 [(-)-6-phosphonomethyl-deca-hydroisoquinoline-3-carboxylic acid], in rats that self-administered cocaine under both fixed ratio (FR) 1 and progressive ratio (PR) schedules of reinforcement. Rats were trained to self-administer cocaine (0.33 mg/infusion) under an FR1 schedule of reinforcement. Thereafter, the effects of pretreatment with LY235959, or the uncompetitive antagonists dextromethorphan and dizocilpine, were examined. The number of infusions earned during the first 10 min of responding under the FR1 schedule was analyzed separately. When rats responded for 0.33 mg/infusion cocaine under an FR1 schedule of reinforcement, 3 mg/kg LY235959 decreased cocaine self-administration only during the first 10 min of the responding. This effect was dose and time dependent and blocked by the competitive NMDA receptor agonist, NMDA. LY235959 (3 mg/kg) decreased total responding for cocaine only when the self-administered dose of cocaine was small (0.02-0.04 mg/infusion) or when responding was reinforced under the PR schedule. In contrast, dizocilpine decreased responding under the FR1 schedule but increased responding under the PR schedule. These data suggest that LY235959 decreased the reinforcing effectiveness of cocaine, a finding reported with systemically administered NMDA receptor antagonists other than dizocilpine.

Animals↗
PubMed1999

A unified analysis of value-function-based reinforcement- learning algorithms.

Reinforcement learning is the problem of generating optimal behavior in a sequential decision-making environment given the opportunity of interacting with it. Many algorithms for solving reinforcement-learning problems work by computing improved estimates of the optimal value function. We extend prior analyses of reinforcement-learning algorithms and present a powerful new theorem that can provide a unified analysis of such value-function-based reinforcement-learning algorithms. The usefulness of the theorem lies in how it allows the convergence of a complex asynchronous reinforcement-learning algorithm to be proved by verifying that a simpler synchronous algorithm converges. We illustrate the application of the theorem by analyzing the convergence of Q-learning, model-based reinforcement learning, Q-learning with multistate updates, Q-learning for Markov games, and risk-sensitive reinforcement learning.

Algorithms↗
PubMed2005

Effects of increased response effort and reinforcer delay on choice and aberrant behavior.

A four-phase investigation was completed to analyze the utility of forced-choice preference assessments when response effort and reinforcer delays are altered within a subsequent reinforcer assessment. The results indicated that access to highly preferred stimuli continued to serve as a reinforcer when increased response effort was required. When reinforcer delay was increased, the utility of preferred stimuli to serve as a reinforcer was variable. Despite stimuli continuing to serve as reinforcers for academic task engagement, increased response effort and reinforcer delay resulted in an increased level of aberrant behavior.

Attention Deficit Disorder with Hyperactivity↗
PubMed1995

Differential effects of methylphenidate and self-reinforcement on attention-deficit hyperactivity disorder.

Six boys aged 9 to 12 years attended a tutoring class focusing on reading for 30 minutes each morning. The investigators employed a modified Latin-square design in which each child began with a 5-day baseline phase followed by six 10-day treatment phases that used drug placebo, noncontingent reinforcers, 0.3 mg/kg methylphenidate, 0.7 mg/kg methylphenidate, and self-reinforcement in various combinations. Amount of academic performance was the major measure of outcome and the target behavior of self-reinforcement. Drug placebo and noncontingent reinforcers had no systematic impact. Methylphenidate had differential effects across the recorded behaviors. Self-reinforcement improved the target behavior; the mean effect size for self-reinforcement was 2.66. The combined effects of methylphenidate and self-reinforcement on academic performance were greater than either of the treatments given alone (mean effect size = 2.89).

Attention Deficit Disorder with Hyperactivity↗
PubMed2005

Hippocampal lesions facilitate instrumental learning with delayed reinforcement but induce impulsive choice in rats.

BACKGROUND: Animals must frequently act to influence the world even when the reinforcing outcomes of their actions are delayed. Learning with action-outcome delays is a complex problem, and little is known of the neural mechanisms that bridge such delays. When outcomes are delayed, they may be attributed to (or associated with) the action that caused them, or mistakenly attributed to other stimuli, such as the environmental context. Consequently, animals that are poor at forming context-outcome associations might learn action-outcome associations better with delayed reinforcement than normal animals. The hippocampus contributes to the representation of environmental context, being required for aspects of contextual conditioning. We therefore hypothesized that animals with hippocampal lesions would be better than normal animals at learning to act on the basis of delayed reinforcement. We tested the ability of hippocampal-lesioned rats to learn a free-operant instrumental response using delayed reinforcement, and what is potentially a related ability -- the ability to exhibit self-controlled choice, or to sacrifice an immediate, small reward in order to obtain a delayed but larger reward. RESULTS: Rats with sham or excitotoxic hippocampal lesions acquired an instrumental response with different delays (0, 10, or 20 s) between the response and reinforcer delivery. These delays retarded learning in normal rats. Hippocampal-lesioned rats responded slightly less than sham-operated controls in the absence of delays, but they became better at learning (relative to shams) as the delays increased; delays impaired learning less in hippocampal-lesioned rats than in shams. In contrast, lesioned rats exhibited impulsive choice, preferring an immediate, small reward to a delayed, larger reward, even though they preferred the large reward when it was not delayed. CONCLUSION: These results support the view that the hippocampus hinders action-outcome learning with delayed outcomes, perhaps because it promotes the formation of context-outcome associations instead. However, although lesioned rats were better at learning with delayed reinforcement, they were worse at choosing it, suggesting that self-controlled choice and learning with delayed reinforcement tax different psychological processes.

Animals↗
PubMed1991

Is there a common biological basis for reinforcement from alcohol and other drugs?

Vulnerability to substance abuse is an important emerging issue. A critical aspect of this phenomenon is the degree to which individuals who abuse one substance are likely to abuse other substances, alone or in combination with each other. The extent to which several distinct drugs will come to serve as positive reinforcers within genetically defined subjects defines their commonality. Questions in this area are directed at determining whether reinforcement from and abuse of alcohol and other drugs define variations within a single behavioral phenomenon, or whether reinforcement and abuse must be individually defined for each substance involved. Findings related to this commonality issue are now emerging from the areas of pharmacogenetics and operant drug self-administration. Previous studies have shown that ethanol can be readily established as a positive reinforcer in LEWIS rats, as well as C57BL/6J mice. In low ethanol preferring F344 rats, ethanol maintains significant but low levels of responding. Ethanol does not maintain lever pressing behavior in BALB/cJ mice, and is avoided in DBA/2J mice. Initial findings reported in this paper show that these genotypic patterns of reinforcement from ethanol appear to correlate highly with patterns of reinforcement from cocaine and opiates. From these findings it is concluded that (1) there exist important genetic determinants of drug reinforced behavior; and (2) drug seeking behaviors maintained by ethanol, cocaine and opiates may have at least some common biological determinants.

Alcohol Drinking↗
PubMed1975

The effects of different reinforcement conditions on the test performance of multihandicapped deaf children.

The present study explored the effects of different reinforcement conditions on the number of correct responses on the Rvaen Progressive Matrices. Four groups of 11- to 18-year-old multihandicapped deaf children matched on the basis of mean age and pretest scores were used. The groups were randomly assigned to any of four posttest conditions: end-of-session reinforcement, noncontingent reinforcement, delayed reinforcement, and immediate reinforcement. The mean posttest score of subjects tested under the immediate-reinforcement condition was significantly higher than that of any other group. No significant differences were observed between the mean posttest scores of the three other groups. The practical implications of using reinforcement procedures for testing purposes are discussed.

Achievement↗
PubMed1996

Using a choice assessment to predict reinforcer effectiveness.

A choice assessment has been found to be a more accurate method of identifying preferences than is single-item presentation. However, it is not clear whether the effectiveness of reinforcement varies positively with the degree of preference (i.e., whether the relative preference based on the results of a choice assessment predicts relative reinforcer effectiveness). In the current study, we attempted to address this question by categorizing stimuli as high, middle, and low preference based on the results of a choice assessment, and then comparing the reinforcing effectiveness of these stimuli using a concurrent operants paradigm. High-preference stimuli consistently functioned as reinforcers for all 4 clients. Middle-preference stimuli functioned as reinforcers for 2 clients, but only when compared with low-preference stimuli. Low-preference stimuli did not function as reinforcers when compared to high- and middle-preference stimuli. These results suggest that a choice assessment can be used to predict the relative reinforcing value of various stimuli, which, in turn, may help to improve programs for clients with severe to profound disabilities.

Adult↗
PubMed1996

Effects of problem difficulty and reinforcer quality on time allocated to concurrent arithmetic problems.

Students with learning difficulties participated in two studies that analyzed the effects of problem difficulty and reinforcer quality upon time allocated to two sets of arithmetic problems reinforced according to a concurrent variable-interval 30-s variable-interval 120-s schedule. In Study 1, high- and low-difficulty arithmetic problems were systematically combined with rich and lean concurrent schedules (nickels used as reinforcers) across conditions using a single-subject design. The pairing of the high-difficulty problems with the richer schedule failed to offset time allocated to that alternative. Study 2 investigated the interactive effects of problem difficulty and reinforcer quality (nickels vs. program money) upon time allocation to arithmetic problems maintained by the concurrent schedules of reinforcement. Unlike problem difficulty, the pairing of the lesser quality reinforcer (program money) with the richer schedule reduced the time allocated to that alternative. The magnitude of this effect was greatest when combined with the low-difficulty problems. These studies have important implications for a matching law analysis of asymmetrical reinforcement variables that influence time allocation.

Achievement↗
PubMed1997

Effects of reinforcer quality on behavioral momentum: coordinated applied and basic research.

The high-probability (high-p) instructional sequence has been an effective treatment for noncompliance. However, treatment failures have also been reported. We hypothesized that the efficacy of the high-p treatment may be improved by using higher quality reinforcers for compliance to high-p instructions. The resistance of compliance to change was tested by varying reinforcer quality in two applied studies and a basic laboratory experiment. Experiment 1 tested the hypothesis that an increase in reinforcer quality for high-p compliance will increase the effectiveness of the high-p treatment when it fails to increase compliance. Experiment 2 assessed the effects of reinforcer quality on resistance of compliance to change by presenting successive low-p requests following the high-p treatment. A basic laboratory study (Experiment 3) was conducted to further isolate the relation between reinforcer quality and behavioral momentum. Two different liquid reinforcers (sucrose and citric acid solutions) were presented in a two-component multiple variable-interval variable-interval schedule followed by a single extinction test session. Results of all three experiments showed a generally consistent relationship between reinforcer quality and behavioral momentum.

Adolescent↗
PubMed1997

Assessment of preference for varied versus constant reinforcers.

One method that has been demonstrated to improve the effectiveness of reinforcement is stimulus (reinforcer) variation (Egel, 1980). Egel found that bar pressing increased and responding occurred more rapidly during varied reinforcement than during constant reinforcement when identical stimuli were used across phases for 10 individuals with autism. The purpose of the current investigation was to assess the preferences of 7 individuals for varied presentation of slightly lower quality stimuli relative to constant access to the highest quality stimulus. Varied presentation was preferred over constant reinforcer presentation with 4 participants, and the opposite was true for 2 participants. One participant did not demonstrate a preference. These results suggest that stimulus variation may allow less preferred reinforcers to compete effectively with a more highly preferred reinforcer for some individuals.

Adolescent↗
PubMed1999

Relative versus absolute reinforcement effects: implications for preference assessments.

We compared results obtained in two previous studies on reinforcer identification (Fisher et al., 1992; Pace, Ivancic, Edwards, Iwata, & Page, 1985) by combining methodologies from both studies. Eight individuals with mental retardation participated. During Phase 1, two preference assessments were conducted, one in which stimuli were presented singly (SS method) and one in which stimuli were presented in pairs (PS method). Based on these results, two types of stimuli were identified for each participant: High-preference (HP) stimuli were those selected on 75% or more trials during both preference assessments; low-preference (LP) stimuli were those selected on 100% of the SS trials but on 25% or fewer of the PS trials. During Phase 2, the reinforcing effects of HP and LP stimuli were evaluated in reversal designs under two test conditions: concurrent and single schedules of continuous reinforcement. Two response options were available under the concurrent-schedule condition: One response produced access to the HP stimulus; the other produced access to the LP stimulus. Only one response option was available under the single-schedule condition, and that response produced access only to the LP stimulus. Results indicated that 7 of the 8 participants consistently showed preference for the HP stimulus under the concurrent schedule. However, when only the LP stimulus was available during the single-schedule condition, response rates for 6 of the 7 participants were as high as those observed for the HP stimulus during the concurrent-schedule condition (1 participant showed no reinforcement effect). These results indicate that, although the concurrent-schedule procedure is well suited to the assessment of relative reinforcement effects (preference for one reinforcer over another), absolute reinforcement effects associated with a given stimulus may be best examined under single-schedule conditions.

Adult↗
PubMed2000

Effects of continuous and intermittent reinforcement for problem behavior during functional communication training.

We evaluated the effectiveness of functional communication training (FCT) in reducing problem behavior and in strengthening alternative behavior when FCT was implemented without extinction. Following the completion of functional analyses in which social-positive reinforcement was identified as the maintaining variable for 5 participants' self-injurious behavior (SIB) and aggression, the participants were first exposed to FCT in which both problem behavior and alternative behavior were reinforced continuously (i.e., on fixed-ratio [FR] 1 schedules). During subsequent FCT conditions, the schedule of reinforcement for problem behavior was made more intermittent (e.g., FR 2, FR 3, FR 5, etc.), whereas alternative behavior was always reinforced according to an FR 1 schedule. Results showed that 1 participant's problem behavior decreased and alternative behavior increased during FCT when both behaviors were reinforced on FR 1 schedules. The remaining 4 participants shifted response allocation from problem to alternative behavior as the schedule of reinforcement for problem behavior became more intermittent. These results suggest that individuals might acquire alternative responses during FCT in spite of inconsistencies in the application of extinction, although even small errors in reinforcement may compromise treatment effects.

Adult↗
PubMed2000

Designing interventions that include delayed reinforcement: implications of recent laboratory research.

UNLABELLED: The search for robust and durable interventions in everyday situations typically involves the use of delayed reinforcers, sometimes delivered well after a target behavior occurs. Integrating the findings from laboratory research on delayed reinforcement can contribute to the design and analysis of those applied interventions. As illustrations, we examine articles from the Journal of the Experimental Analysis of Behavior that analyzed delayed reinforcement with respect to response allocation (A. M. Williams & Lattal, 1999), stimulus chaining (B. A. Williams, 1999), and self-control (Jackson & Hackenberg, 1996). These studies help to clarify the conditions under which delayed reinforcement (a) exercises control of behavior, (b) entails conditioned reinforcement, and (c) displaces the effects of immediate reinforcement. The research has applied implications, including the development of positive social behavior and teaching people to make adaptive choices. DESCRIPTORS: delayed reinforcement, response allocation, stimulus chains, self-control, integration of basic and applied research

Humans↗