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PubMed1975

Ethanol as a reinforcer for rats: effects of concurrent access to water and alternate positions of water and ethanol.

Water and ethanol solutions were concurrently made available on a continuous reinforcement schedule to 4 food-deprived male albino rats during daily 1-hr sessions in an operant conditioning chamber equipped with 2 levers and 2 liquid dippers. The number of ethanol reinforcements substantially exceeded the number of water reinforcements for each rat at each concentration studied (8, 16, and 32% w/v). Water reinforcements were low in number and did not vary with ethanol concentration. As the ethanol concentration was increased, the number of ethanol reinforcements obtained decreased, while the quantity consumed (mg/100 g of body weight/hr) increased. The highest rate of responding occurred at the beginning of the session.

Alcohol Drinking↗
PubMed2002

Potential role for the hypothalamo-pituitary-adrenal axis in the conditioned reinforcer-induced reinstatement of extinguished cocaine seeking in rats.

RATIONALE: We have previously reported that pretreatment with the corticosterone synthesis inhibitor ketoconazole blocks the electric foot-shock-induced reinstatement of cocaine-seeking behavior in rats, suggesting a potential role for the hypothalamo-pituitary-adrenal (HPA) axis in this animal model of relapse. OBJECTIVES: This experiment was designed to investigate whether or not ketoconazole would also inhibit the reinstatement of cocaine seeking induced by the presentation of a conditioned reinforcer. The effects of the corticotropin-releasing hormone 1 (CRH1) receptor antagonist CP-154,526 were also investigated to further determine the involvement of the HPA axis in this behavior. METHODS: Adult male rats were implanted with jugular catheters and trained to self-administer cocaine (0.25 mg/kg per infusion) during daily 2-h sessions. During training, cocaine delivery was paired with the presentation of a tone and the illumination of a house light. Once a stable baseline of cocaine self-administration was observed, lever pressing was extinguished to less than 20% of baseline rates. During reinstatement testing, responding by rats in the contingent group resulted in the presentation of the conditioned reinforcer (i.e., the house light and tone previously paired with self-administered cocaine). Rats in the non-contingent group were presented with the tone/house light compound stimulus once every 5 min, regardless of responding. Rats were pretreated with ketoconazole (25 mg/kg, i.p.) or CP-154,526 (20 mg/kg, i.p.) 30 min prior to testing for reinstatement with the contingent presentation of the conditioned reinforcer to determine the role for the HPA axis in this behavior. RESULTS: The response-contingent presentation of the conditioned reinforcer reliably reinstated extinguished cocaine-seeking behavior, while the non-contingent presentation of the same stimulus did not. Increases in plasma corticosterone were evident during cocaine self-administration as well as during extinction and reinstatement testing. However, while plasma corticosterone returned to basal levels by the end of the session during extinction, it remained elevated through the end of the session during reinstatement. Pretreatment with ketoconazole reversed the conditioned reinforcer-induced reinstatement of extinguished cocaine-seeking behavior and also attenuated the conditioned increases in plasma corticosterone observed during reinstatement. Pretreatment with CP-154,526 resulted in a similar decrease in cocaine seeking. CONCLUSIONS: These data suggest a potential role for the HPA axis in the ability of environmental cues to stimulate cocaine-seeking behavior.

Analysis of Variance↗
PubMed2000

Reinforcing effects of contingently administered subcutaneous injections of etonitazene in rats.

RATIONALE: Response-contingent injections of opioids have been shown to control behavior in various species. OBJECTIVE: To determine whether s.c. injections of etonitazene (ETZ) could maintain behavior in rats when administered under a single fixed-interval schedule. METHODS: Rats were trained to lever press for eight 45-mg food pellets under a single fixed-interval (FI) 10-min schedule of reinforcement: following passage of the 10-min interval, each lever press resulted in a pellet delivery until eight pellets were obtained. Delivery of the reinforcer was signaled by a change in visual stimulus conditions. Once stable responding for the food pellets under the FI 10-min schedule was established, a s.c. injection of 3.2 micrograms/kg ETZ was administered to the rat by the investigator following schedule completion and delivery of the food pellets. After receiving the drug injection, rats were returned to the experimental chamber for 30 min and exposed to the same stimulus conditions that accompanied food reinforcement. Across sessions, the number of food pellets was decreased until rats were responding solely for the drug. RESULTS: Responding for the s.c. administered drug stabilized and persisted across sessions. When saline vehicle injections were substituted for the drug injections, responses diminished across sessions to levels below that of the drug baseline. Subsequent alternating blocks of ETZ and vehicle injections produced respective increases and decreases in responding. CONCLUSION: This study demonstrates that response-contingent s.c. injections of a drug can control behavior in rats, systematically replicating a previous experiment that used the i.p. route. Since all pertinent operant behavior is emitted prior to the administration of drug, this procedure can be used for testing the reinforcing effects of a drug without interference from any direct (rate-altering) drug effects. The present findings also extend the conditions under which drugs of abuse may reinforce behavior.

Animals↗
PubMed2005

The effects of the quality and probability of reinforcement on feeder selection by lobectomized dogs.

The role of the prefrontal cortex was studied in an active selection situation in which dogs had to choose one of two feeders, with changes in the quality and probability of the reinforcement provided in one of the feeders. The study was performed in two stages. Before surgery, animals were trained to place themselves on a start area during the interstimulus interval. Dogs were presented with a conditioned stimulus for investigation of the sequence of selection of feeders with identical reinforcements. After bilateral extirpation of the prefrontal areas (the proreal gyrus), dogs continuously ran from one feeder to the other during the interstimulus period. In response to the conditioned stimulus, the animals repeated the reaction of selecting the same feeder on many occasions during the first few (7-9) days. When there was a conflict between the probability and quality of reinforcement, the dogs came to prefer the feeder with the greater reinforcement quality despite its lower probability of presentation. In our experiments, operated animals presented with food at probabilities of 30% and 100% performed feeder selections with different probabilities. One of the functions of the prefrontal cortex in intact animals would appear to be to support the reaction of selecting the greater probability of reinforcement.

Animals↗
PubMed1984

General level of reinforcement.

A concept of General Level of Reinforcement (GLR) is introduced. This concept is defined as the number, quality and duration of reinforcements per unit time. The assumptions of this theory are discussed. A crucial assumption is that the theory is related to psychological and physiological well-being. Ways to measure general level of reinforcement are described, and clinical implications presented. Methods to increase the level of reinforcement, such as covert reinforcement and the Self-Control Triad, are specified. Finally, suggestions for research are provided.

Behavior Therapy↗
PubMed1983

Differential reinforcement of other-than-vocalization as a control procedure in the conditioning of infant vocalization rate.

The purpose of the present study is to demonstrate reinforcement control over infant vocalization rates using a DRO schedule to control for elicitation of social stimulation. Mothers of four 2 1/2- to 3-month-old infants provided social reinforcement for their infants' vocalization under two schedules: continuous reinforcement (CRF) and differential reinforcement of other-than-vocalization (DRO). In a repeated-reversal single-subject experimental design, all four infants produced systematically higher vocalization rates during CRF, even though densities of social stimulation during DRO were equal to or greater than densities provided during CRF. Thus, whatever its elicitation value, social stimulation may reinforce infant vocalization rates.

Conditioning, Operant↗
PubMed2004

Reinforcer concentration effects on a fixed-interval schedule.

Four rats received training on a mixed FI 30-s FI 150-s schedule, where the different FI values were associated with different levers. During baseline, the reinforcer was a 30% concentration of condensed milk. During subsequent testing sessions, the reinforcer concentration was varied within sessions over values of 10, 30, 50, and 70%. Measures of behaviour were taken from the FI 30-s lever during trials where the reinforcer was delivered for responses on the other lever. Increasing the reinforcer concentration which began the interval (a) increased the time to start responding in the interval, and (b) increased the location of the response peak on the FI 30-s lever (often to values well above 30s). Response rate at the peak, and spread of the response rate versus time function, changed much less with reinforcer concentration. The data are discussed relative to predictions derived from Scalar Expectancy Theory, the Behavioural Theory of Timing, and the Tuned-trace model.

Animals↗
PubMed2002

The observing-response procedure: a novel method to study drug-associated conditioned reinforcement.

In this experiment, the observing-response procedure was adapted for use with drug self-administration. Rats' responding for oral ethanol was sometimes reinforced on a random-ratio schedule, whereas at other times it had no effect (i.e., extinction). Behavior producing stimuli associated with the otherwise unsignaled random-ratio and extinction periods (i.e., observing behavior) was acquired and maintained. In a vehicle control condition, both self-administration and observing behavior decreased, but observing decreased less rapidly proportionally to baseline than vehicle consumption. Thus, conditioned reinforcers may have persistent effects that are relatively independent of the current status of the primary reinforcer. The procedure allows long-term study of drug-associated conditioned reinforcement and provides independent indexes of the conditioned reinforcing and discriminative stimulus effects of drug stimuli.

Animals↗
PubMed2000

Relative persistence of behavior: a fundamental measure of relative reinforcing effects.

Relative persistence of behavior is measured in terms of rates of behavior at a higher schedule value divided by rates of behavior at a lower schedule value and then multiplied by 100 to express the result as a percentage. Relative persistence of behavior is a direct function of reinforcer size over a broad range of values. In 1 study, food was the reinforcer; however, in most studies of persistence, drug reinforcers were used, and the drugs were taken orally or intravenously. A variety of reinforcing drugs were studied: barbiturates, opioids, psychomotor stimulants, a dissociative anesthetic, and alcohol. Both ratio and interval schedules were used to study relative persistence of behavior in human participants, male and female rhesus monkeys (Macaca mulatta), and rats. Thus, studies of persistence are based on results of an extensive set of conditions. The results support the proposition that relative persistence of behavior is a fundamental measure of relative reinforcing effects.

Animals↗
PubMed1975

Partial reinforcement effects in classical aversive conditioning in rabbits and human beings.

The partial reinforcement extinction effect (the PREE) in classical aversive conditioning was investigated in 2 experiments. In the first, the nictitating membrane responses of 120 rabbits were conditioned at a 250-msec. interstimulus interval (ISI) under continuous reinforcement, partial reinforcement with the unconditioned stimulus (US) omitted (Group PO), or partial reinforcement with the US delayed to 1,500 msec. (Group PD). These 3 groups were factorially extinguished under US-Omitted, US-Unpaired, or US-Delayed extinction regimens. A significant PREE was obtained, but only for PO training and US-Omitted extinction. The second experiment, employing human subjects in a masked eye blink conditioning task, produced parallel results. A general discrimination view of the classical PREE seems applicable, but one in which neither cognitive factors nor intertrial conditioning of reinforcement aftereffects play a significant role.

Acoustic Stimulation↗
PubMed2004

Exposure to delta-9-tetrahydrocannabinol (THC) increases subsequent heroin taking but not heroin's reinforcing efficacy: a self-administration study in rats.

One concern about the widespread use of cannabis is that exposure to its active ingredient, delta-9-tetrahydrocannabinol (THC), might increase future reinforcing effects of other abused drugs such as heroin. In this study, we investigated the effects of pre-exposure to THC on subsequent intravenous self-administration of heroin by Sprague-Dawley rats. In one group of rats, we studied (1) acquisition of heroin self-administration behavior using a continuous-reinforcement (fixed-ratio (FR) 1) schedule, (2) heroin dose-response relationships using an FR1/variable-dose schedule, and (3) reinforcing efficacy of heroin using a progressive-ratio schedule. The number of rats pre-exposed to THC that subsequently learned to self-administer 50 microg/kg injections of heroin within 10 daily sessions did not differ from vehicle-pretreated controls. In contrast, rats pre-exposed to THC subsequently self-administered significantly more heroin injections per session and showed significantly shorter post-injection pauses over a range of heroin doses (12.5-100 microg/kg/injection) using the variable-dose schedule. Interestingly, the maximum effort rats would exert to receive an injection of the different doses of heroin under the progressive-ratio schedule was not altered by THC pre-exposure. In a second group of rats, we varied the 'price' of heroin (responses required/dose), by manipulating FR response requirements at different doses of heroin across sessions, to calculate demand and response output curves. Again, consumption was significantly higher in the THC-treated rats at the lowest prices of heroin (FR1/100 microg/kg and FR1/50 microg/kg) but there were no differences in the reinforcing efficacy of heroin between THC- and vehicle-pretreated rats. Altogether, these results demonstrate that pre-exposure to THC alters some pharmacological effects of heroin that determine frequency of heroin taking, but offer no support for the hypothesis that pre-exposure to THC alters heroin's efficacy as a reinforcer.

Analgesics, Non-Narcotic↗
PubMed2005

Motivational effects of cannabinoids and opioids on food reinforcement depend on simultaneous activation of cannabinoid and opioid systems.

Strong functional interactions exist between endogenous cannabinoid and opioid systems. Here, we investigated whether cannabinoid-opioid interactions modulate motivational effects of food reinforcement. In rats responding for food under a progressive-ratio schedule, the maximal effort (break point) expended to obtain 45 mg pellets depended on the level of food deprivation, with free-feeding reducing break points and food-deprivation increasing break points. Delta-9-tetrahydrocannabinol (THC; 0.3-5.6 mg/kg intrapeitoneally (i.p.)) and morphine (1-10 mg/kg i.p.) dose-dependently increased break points for food reinforcement, while the cannabinoid CB1 receptor antagonist rimonabant (SR-141716A; 0.3-3 mg/kg i.p.) and the preferential mu-opioid receptor antagonist naloxone (0.3-3 mg/kg i.p.) dose-dependently decreased break points. THC and morphine only increased break points when food was delivered during testing, suggesting that these treatments directly influenced reinforcing effects of food, rather than increasing behavior in a nonspecific manner. Effects of THC were blocked by rimonabant and effects of morphine were blocked by naloxone, demonstrating that THC's effects depended on cannabinoid CB1 receptor activation and morphine's effects depended on opioid-receptor activation. Furthermore, THC's effects were blocked by naloxone and morphine's effects were blocked by rimonabant, demonstrating that mu-opioid receptors were involved in the effects of THC and cannabinoid CB1 receptors were involved in the effects of morphine on food-reinforced behavior. Thus, activation of both endogenous cannabinoid and opioid systems appears to jointly facilitate motivational effects of food measured under progressive-ratio schedules of reinforcement and this facilitatory modulation appears to critically depend on interactions between these two systems. These findings support the proposed therapeutic utility of cannabinoid agonists and antagonists in eating disorders.

Analgesics, Non-Narcotic↗
PubMed2003

Response persistence under variable-time schedules following immediate and unsignalled delayed reinforcement.

Key pecking of three pigeons was maintained in separate components of a multiple schedule by either immediate reinforcement (i.e., tandem variable-time fixed-interval schedule) or unsignalled delayed reinforcement (i.e., tandem variable-interval fixed-time schedule). The relative rate of food delivery was equal across components, and this absolute rate differed across conditions. Immediate reinforcement always generated higher response rates than did unsignalled delayed reinforcement. Then, variable-time schedules of food delivery replaced the contingencies just described such that food was delivered at the same rate but independently of responding. In most cases, response rates decreased to near-zero levels. In addition, response persistence was not systematically different between multiple-schedule components across pigeons. The implications of the results for the concepts of response strength and the response-reinforcer relation are noted.

Animals↗
PubMed1999

A comparison of measures of relative reinforcing efficacy and behavioral economics: cigarettes and money in smokers.

In this experiment, we compared behavioral economic measures and measures of the relative reinforcing efficacy of cigarettes and money between-participants. The experiment proceeded in two phases. In the first phase, money and cigarettes were available on separate progressive ratio (PR) schedules when they were solely available. The response requirement for the PR schedule increased across sessions, rather than within a session. In the second phase, money and cigarettes were made concurrently available at some of the response requirements employed during the PR schedule. Measures of (1) PR breakpoint, (2) peak response rate, (3) preference, (4) elasticity and (5) Pmax (the price at which the greatest amount of responding occurs) were compared within participant. Across the PR- and concurrent-schedule conditions, the three measures of reinforcing efficacy (breakpoint, response rate and preference) yielded an inconsistent assessment of the relative reinforcing efficacy of money and cigarettes. The reinforcer that resulted in greater peak response rates varied across subjects, while PR breakpoint was higher for cigarettes in all participants. Further, in concurrent schedules, preferences for cigarettes or money reversed across the response requirements. Behavioral economic analyses suggest that Pmax and elasticity are related to PR breakpoint, and that preference can be predicted from a comparison of the demand curves under single-schedule conditions. Implications for the concept of reinforcing efficacy are discussed.

Adult↗
PubMed1983

Sensory and social reinforcement of head-turning in a profoundly retarded multiply handicapped child.

Head-turning by a nine-year-old multiply handicapped profoundly retarded child (highest item passed on the Mental Scale of the Bayley Infant development test: 2.6 months; highest item passed on Motor Scale of Infant development test: 0.1 month) was reinforced by a variety of potential reinforcers: auditory; vibratory; social; visual. In addition various elicitation and shaping procedures were employed. Relative to base-line performance only visual reinforcement produced a substantial increase in head-turning. This finding is discussed in terms of the compatibility of operant and reinforcer and is related to the recent literature on constraints and predispositions in learning. The extent to which visual reinforcement also had eliciting effects is considered and further experimental controls and operations described.

Acoustic Stimulation↗
PubMed2005

Prolonged increase in the sensitivity of the posterior ventral tegmental area to the reinforcing effects of ethanol following repeated exposure to cycles of ethanol access and deprivation.

The posterior ventral tegmental area (VTA) is a neuroanatomical substrate mediating the reinforcing effects of ethanol in rats. Repeated alcohol deprivations produce robust ethanol intakes of alcohol-preferring (P) rats during relapse and increase the reinforcing effects of oral alcohol self-administration. The objective of this study was to test the hypothesis that alcohol drinking and repeated alcohol deprivations will increase the reinforcing effects of ethanol within the posterior VTA of P rats. Groups of female P rats were used (alcohol-naive, continuous access, and repeatedly deprived). Each rat was implanted with a guide cannula aimed at the posterior VTA. Depression of the active lever produced the infusion of 100 nl of artificial cerebrospinal fluid (CSF) or ethanol (25-300 mg%). Each rat was given only one ethanol concentration during the 4-h sessions conducted every other day. Compared with the infusions of artificial CSF, the alcohol-naive group reliably self-infused 75 and 150 mg% ethanol, but not the lower or higher concentrations. On the other hand, the continuous access group had significantly higher self-infusions of 50, 75, 150, and 300 mg% ethanol compared with artificial CSF infusions. The repeatedly deprived group also self-infused significantly more of 50, 75, 150, and 300 mg% ethanol than artificial CSF; moreover, the number of infusions for all four concentrations was higher in the repeatedly deprived versus the continuous access group. Chronic alcohol drinking by P rats increased the reinforcing effects of ethanol within the posterior VTA, and repeated alcohol deprivations produced a further increase in these reinforcing effects of ethanol.

Alcohol Drinking↗
PubMed1991

Contingent reinforcement of abstinence with individuals abusing cocaine and marijuana.

Two males diagnosed with cocaine dependence received a behavioral intervention comprised of contingency management and the community reinforcement approach. During the initial phase of treatment, reinforcement was delivered contingent on submitting cocaine-free urine specimens. The community reinforcement approach involved two behavior therapy sessions each week. Almost complete cocaine abstinence was achieved, but regular marijuana use continued. During a second phase, reinforcement magnitude was reduced, but remained contingent on submitting cocaine-free specimens. Behavior therapy was reduced to once per week. Cocaine abstinence and regular marijuana use continued. Next, reinforcement was delivered contingent on submitting cocaine- and marijuana-free specimens. This modified contingency resulted in an abrupt increase in marijuana abstinence and maintenance of cocaine abstinence. One- and 5-month follow-ups indicated that cocaine abstinence continued, but marijuana smoking resumed. These results indicate that the behavioral intervention was efficacious in achieving abstinence from cocaine and marijuana; maintenance, however, was achieved for cocaine only.

Adult↗
PubMed1998

Treatment of pica through multiple analyses of its reinforcing functions.

We conducted functional analyses of the pica of 3 participants. The pica of 1 participant appeared to be maintained by automatic reinforcement; that of the other 2 participants appeared to be multiply controlled by social and automatic reinforcement. Subsequent preference and treatment analyses were used to identify stimuli that would complete with the automatic function of pica for the 3 participants. These analyses also identified the specific aspect of oral stimulation that served as automatic reinforcement for 2 of the participants. In addition, functional analysis-based treatments were used to address the socially motivated components of 2 of the participants' pica. Results are discussed in terms of (a) the importance of using the results of functional analyses to develop treatments for pica and (b) the advantages of developing indirect analyses to identify specific sources of reinforcement for automatically reinforced behavior.

Adolescent↗