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PubMedDate not supplied

Motivation and reinforcement in the systemic mechanisms of behavior: dynamic reinforcement engrams.

Materials are presented which suggest the interaction of motivation and reinforcement in the systemic organization of behavioral acts in individual brain neurons. It was demonstrated that immune mechanisms participate in the interaction of motivation and reinforcement. It is postulated that reinforcement during learning, by means of backward afferentation, forms molecular reinforcement engrams in the neuronal structures of the action outcome acceptor. The molecular reinforcement engrams are built by processes of the synthesis of DNA and protein molecules in ribosomes. These engrams, during the succeeding appearances of the corresponding needs, are activated by the dominant motivation and in anticipation direct animals toward the satisfaction of their initial needs.

Animals↗

PubMed2000

Second-order schedules of drug reinforcement in rats and monkeys: measurement of reinforcing efficacy and drug-seeking behaviour.

RATIONALE AND OBJECTIVES: To review the literature on the use of second-order schedules of drug reinforcement in the context of experimental investigations of the neural and pharmacological mechanisms underlying addictive behaviour in general and drug-seeking behaviour in particular. METHODS: Second-order schedules of drug reinforcement are described in which responding is maintained not only by the self-administered drug, but also by contingent presentation of drug-paired stimuli that serve as conditioned reinforcers of instrumental behaviour. RESULTS: The behaviour of rats and monkeys responding under second-order schedules is discussed in relation to self-administered drug dose and the importance of drug-associated cues in maintaining responding for cocaine, morphine or heroin. Drug-seeking behaviour during the period before drug is self-administered is described and compared with drug-seeking behaviour derived from other procedures. In addition, results are summarised that demonstrate the differential involvement of the amygdala and prefrontal cortex in the acquisition of cue-controlled cocaine- and heroin-seeking behaviour, as well as the effects of drugs interacting with D3 dopamine, NMDA and AMPA receptors on drug-seeking behaviour and dopaminergic correlates of drug-paired stimuli presented non-contingently and during responding for cocaine under a second-order schedule. CONCLUSIONS: We argue that the first, drug-free interval (or other period) of responding under a second-order schedule of reinforcement has particular utility in that it provides a measure of drug-seeking behaviour and reinforcing efficacy that are not affected by the pharmacological effects of recently administered drug. It also provides a means of investigating the role of drug-paired stimuli in drug-seeking behaviour, including its behavioural, neural and neurochemical basis.

Animals↗

PubMed2000

Reinforcing and subjective effects of morphine in human opioid abusers: effect of dose and alternative reinforcer.

RATIONALE: Although most opioid self-administration research has been conducted with laboratory animals, such research with humans is necessary to answer questions unique to human drug-taking behavior. OBJECTIVE: We investigated the influence of morphine dose and an alternative non-drug reinforcer on choice between morphine versus money and examined the relationship between drug-reinforced behavior and subjective euphoria. METHODS: Five male opioid users participated in the 7-week study. During the first 5 weeks, a single dose of morphine (0, 4, 8, 16, or 32 mg/70 kg) was available each week. On Monday, subjects received an IM injection of the dose tested that week. On Tuesday, Thursday, and Friday, subjects could work for morphine or money under a second-order, progressive ratio schedule. For each primary ratio completed on the drug lever, subjects earned one-ninth of the available drug dose, and for each ratio completed on the money lever, subjects earned $1. Total amount of drug earned was administered in a single IM injection at the end of the session; money earned was credited to the subject's account. RESULTS: As morphine dose increased, responding for drug increased in an orderly manner and responding for money decreased. During the final phase of the study, the lowest and highest doses that maintained drug responding for each subject were repeated, and the value of the alternative reinforcer was increased to $2 per ratio. This manipulation was associated with decreased drug-maintained responding at the lowest, but not the highest, reinforcing dose of morphine. CONCLUSION: The progressive ratio, concurrent access procedure may be useful in predicting the outcome of drug abuse treatment interventions that use alternate reinforcement strategies.

Adult↗

PubMed1999

Voucher-based reinforcement of cocaine abstinence in treatment-resistant methadone patients: effects of reinforcement magnitude.

Voucher-based reinforcement of cocaine abstinence has been one of the most effective means of treating cocaine abuse in methadone patients, but it has not been effective in all patients. This study was designed to determine if we could promote cocaine abstinence in a population of treatment-resistant cocaine abusing methadone patients by increasing the magnitude of voucher-based abstinence reinforcement. Participants were 29 methadone patients who previously failed to achieve sustained cocaine abstinence when exposed to an intervention in which they could earn up to $1155 in vouchers (exchangeable for goods/services) for providing cocaine-free urines. Each patient was exposed in counterbalanced order to three 9-week voucher conditions that varied in magnitude of voucher reinforcement. Patients were exposed to a zero, low and high magnitude condition in which they could earn up to $0, $382, or $3480 in vouchers for providing cocaine-free urines. Analyses for 22 patients exposed to all three conditions showed that increasing voucher magnitude significantly increased patients' longest duration of sustained cocaine abstinence (P<0.001) and percent of cocaine-free urines (P<0.001), and significantly decreased patients' reports of cocaine injections (P=0.024). Almost half (45%) of the patients in the high magnitude condition achieved >/=4 weeks of sustained cocaine abstinence, whereas only one patient in the low and none in the zero magnitude condition achieved more than 2 weeks. Reinforcement magnitude was a critical determinant of the effectiveness of this abstinence reinforcement intervention.

Adult↗

PubMed2001

Reinforcement by orally delivered methadone, cocaine, and methadone-cocaine combinations in rhesus monkeys: are the combinations better reinforcers?

RATIONALE: Polydrug abuse is a problem that has been infrequently examined. In the present study, drug self-administration procedures were used to investigate the reinforcing effects of drug combinations. OBJECTIVES: To determine the absolute and relative response rates maintained by orally delivered methadone, cocaine, and their combinations under sequential and concurrent access. Choice between drug combinations containing different concentrations of cocaine was also determined. METHODS: Oral intake of methadone, cocaine, and their combinations was studied with rhesus monkeys during daily 3-h sessions. Lip contact (the operant response) was reinforced by delivery of liquid contingent upon completion of a fixed-ratio schedule. In one series, the drugs and drug combinations were studied sequentially with the water vehicle concurrently available. In the next series, the drugs and drug combinations were concurrently available. In the third series, pairs of drug combinations containing different concentrations of cocaine were also concurrently available. RESULTS: Methadone, cocaine and their combinations functioned as reinforcers. Under sequential access, response rates for the drug combinations and the component drugs were often similar. However, under concurrent access, response rates for the drug combinations were greater than response rates for the component drugs at the highest FR size for each condition. Also, drug combinations containing higher cocaine concentrations were preferred to combinations containing lower cocaine concentrations. CONCLUSIONS: Combinations of methadone and cocaine have relatively greater reinforcing effects than the component drugs, and these greater reinforcing effects are better detected with concurrent measures than with sequential measures.

Administration, Oral↗

PubMedDate not supplied

Evaluating the reinforcing effects of choice in comparison to reinforcement rate.

A concurrent-operants arrangement was used to evaluate a boy's preference for a choice condition (in which he chose the reinforcement) over a no-choice condition (in which the therapist selected the reinforcement for him) when (a) these conditions produced equal rates of reinforcement and (b) lower rates of reinforcement were associated with the choice condition. The boy preferred the choice condition even when it resulted in a much less favorable rate of reinforcement than the no-choice condition (up to 4000% less).

Aggression↗

PubMed2004

A partial reinforcement extinction effect despite equal rates of reinforcement during Pavlovian conditioning.

In 4 experiments rats received appetitive Pavlovian conditioning followed by extinction. Food accompanied every trial with the conditioned stimulus (CS) for the continuously reinforced groups and only half of the trials for the partially reinforced groups. In contrast to previous experiments that have compared the effects of partial and continuous reinforcement, the rate at which food was delivered during the CS was the same for both groups. The strength of the conditioned response during extinction weakened more rapidly in the continuously than in the partially reinforced groups. The results demonstrate that the partial reinforcement extinction effect is a consequence of the nonreinforced trials with the CS, rather than the rate at which the unconditioned stimulus is delivered during the CS.

Animals↗

PubMed1994

Effects of reinforcer duration on the response behavior of preterm 2-year-olds in visual reinforcement audiometry.

The purpose of this study was to investigate the effects of reinforcer duration (0.5, 1.5, and 4.0 sec) on response behavior to a 50-dB HL complex noise bandpass signal in visual reinforcement audiometry (VRA). Sixty preterm 2-year-olds (corrected age 24-30 mo) met the selection criteria and were used as subjects. Data indicated that decreasing the duration of a subject's exposure to the visual reinforcer resulted in more responses, with significantly slower habituation rates presented by subjects receiving brief (0.5 sec) versus long (4.0 sec) reinforcer duration. These results suggest that audiologists may increase the amount of audiometric information obtained from children in the upper age bracket of VRA by decreasing their exposure to the visual reinforcer.

Acoustic Stimulation↗

PubMed2004

Preferential effects of the metabotropic glutamate 2/3 receptor agonist LY379268 on conditioned reinstatement versus primary reinforcement: comparison between cocaine and a potent conventional reinforcer.

Metabotropic glutamate receptors (mGluRs) have been implicated in regulating anxiety, stress responses, and the neurobehavioral effects of psychostimulants. The present study sought to determine whether group II mGluR activation by the potent mGlu2/3 receptor agonist, (-)-2-oxa-4-aminobicylco hexane-4,6-dicarboxylic acid (LY379268), antagonizes reinstatement of cocaine-seeking induced by cocaine-related stimuli and whether this effect extends to behavior induced by stimuli conditioned to a potent conventional reinforcer, sweetened condensed milk (SCM). Also, we tested whether the suppressant effects of LY379268 on conditioned reinstatement extend to the primary reinforcing effects of cocaine or SCM. Rats were trained to associate discriminative stimuli (S(D)) with the availability of cocaine or SCM versus non-reward and then subjected to repeated extinction sessions during which the respective reinforcers and S(D) were withheld. Subsequent reexposure to the cocaine or SCM S(D), but not the non-reward S(D), produced recovery of responding at the previously active lever. LY379268 (0.3-3.0 mg/kg, s.c.) dose-dependently attenuated recovery of cocaine seeking but reduced conditioned reinstatement by the SCM S(D) only at the highest dose. LY379268 did not alter responding reinforced directly by SCM, and only the highest LY379268 dose reduced cocaine self-administration. The results suggest that the effects of LY379268 are selective for behavior maintained by cocaine as opposed to palatable conventional reinforcers. More importantly, the results show that LY379268 suppresses behavior motivated by stimuli conditioned to cocaine or SCM more effectively than consummatory behavior maintained by the unconditioned effects of these substances. As such, the results identify group II mGluRs as a pharmacotherapeutic target for craving and relapse prevention associated with cocaine cue exposure.

Amino Acids↗

PubMed1997

Key pecking during extinction after intermittent or continuous reinforcement as a function of the number of reinforcers delivered during training.

Key pecking by 7 pigeons was established and maintained on a multiple variable-ratio variable-ratio (VR) schedule of food presentation. The schedule in one of the components was then changed to fixed-ratio (FR) 1 for a predetermined number of reinforcers. Both components were then changed to extinction (i.e., multiple extinction, extinction). This sequence was repeated a different number of times for each pigeon to determine the relation between the number of reinforcers delivered during each component of the multiple VR FR 1 schedule and the number of responses during extinction. For most pigeons, there were fewer responses during extinction in the presence of a stimulus recently correlated with FR 1, regardless of the number of reinforcers received. The ratio of the total responses in extinction in the former VR component to the total responses in the former FR 1 component increased as the number of reinforcers delivered during each component of the multiple schedule increased. Within-subject replications of the partial-reinforcement extinction effect generally occurred, and there were no overall reductions in the number of responses in extinction with repeated exposures to extinction.

Animals↗

PubMed2004

[Within-session changes in responding to water reinforcement: effects of variability in the duration of reinforcement].

This study tested the hypothesis (McSweeney & Swindell, 1999) that habituation contributes to within-session decreases in drinking. Six rats' lever-pressing was reinforced by water under a continuous reinforcement (CRF) schedule. During the fixed amount sessions, duration of reinforcement was fixed at 3 seconds. Reinforcement duration varied from 1 to 5 seconds, with a mean of 3 seconds, during variable amount sessions. Experimental phase lasted 10 successive days and consisted of 5 fixed amount and 5 variable amount sessions, alternating day by day. Within-session decreases in responding were steeper during fixed amount than variable amount sessions. In addition, response rates were well described as linear functions of cumulative number of reinforcements. The regression line for the fixed amount sessions had steeper slope and smaller x-axis intercept than those for the variable amount sessions. These results support the habituation hypothesis and are not explained by post-ingestive factors.

Animals↗

PubMed1981

Aversion to the reinforcer differentially affects conditioned reinforcement and instrumental responding.

Rats were trained to press a bar for sucrose solution delivered by a dipper; they then received pairings of sucrose and lithium chloride (LiCl) in the home cage and were tested for bar pressing. In the first and second experiments, the conditioned aversion to sucrose had no effect on unreinforced bar pressing in the test, but the aversion reduced bar pressing reinforced either by sucrose or by the operation of the empty dipper. In the third and fourth experiments, presses during training were reinforced by sucrose only in the presence of an audiovisual discriminative stimulus; in the test, the aversion to sucrose reduced pressing reinforced by the discriminative stimulus, but the aversion had no effect on unreinforced pressing in either the presence or the absence of the discriminative stimulus. Thus, pairings of sucrose and LiCl reduced the reinforcing value of sucrose and also of a stimulus previously paired with sucrose, but they had no effect of an instrumental response previously reinforced by sucrose or on the discriminative properties of a stimulus paired with sucrose.

Animals↗

PubMed1996

Visual Reinforcement Signals Interfere with the Effects of Reinforcer Magnitude Manipulations

Three experiments examined the effect of reinforcement magnitude on free-operant response rates. In Experiment 1, rats that received four food pellets responded faster than rats that received one pellet on a variable ratio 30 schedule. However, when the food hopper was illuminated during reinforcer delivery, there was no difference between the rates of response produced by the two magnitudes of reward. In Experiment 2, there was no difference in response rates emitted by rats receiving either one or four pellets of food as reward on a random interval (RI) 60-s schedule. In Experiment 3, rats responding on an RI 30-s schedule did so at a lower rate with four pellets as reinforcement than with one pellet. This effect was abolished by the illumination of the food hopper during reinforcement delivery. These results indicate that the influence of magnitude is obscured by manipulations which signal the delivery of reinforcement.

Journal Article↗

PubMed1973

Reinforcer effectiveness as a function of reinforcer rate and magnitude: a comparison of concurrent performances.

Pigeons' pecks on each of two concurrently available response keys were reinforced under a variable-interval schedule that sometimes allotted food-pellet deliveries to one key and sometimes to the other. The keys differed in the number of reinforcements assigned to each and in the number of pellets delivered during each reinforcement. When the total quantity of food associated with each key during a session was constant, the proportion of responses to a key depended on the particular combinations of reinforcer rate and reinforcer magnitude scheduled on each key. A given quantity of food generated more responding on a key when it was delivered frequently in small amounts than when it was delivered infrequently in large amounts.

Journal Article↗

PubMed1978

Relationship between response rate and reinforcement frequency in variable-interval schedules: the effect of the concentration of sucrose reinforcement.

Four rats were exposed to variable-interval schedules specifying a range of different reinforcement frequencies, using sucrose of two different concentrations and distilled water as the reinforcer. With sucrose, the rates of responding of all four rats were increasing negatively accelerated functions of reinforcement frequency, the data conforming closely to Herrnstein's equation; this was also true of the data from three of the four rats when distilled water was used as the reinforcer. The values of both constants in Herrnstein's equation were related to the sucrose concentration: the asymptotic response rate decreased, and the reinforcement frequency corresponding to the half-maximal response rate increased, with decreasing sucrose concentration.

Journal Article↗

PubMed1979

Effects of response-independent negative reinforcers on negatively reinforced key pecking.

Previous research has shown that presenting response-independent positive reinforcers reduces the response rate of an operant maintained by positive reinforcement. The present experiment investigated a similar effect using shock-free time as a negative reinforcer. Brief shocks were delivered in the presence of a distinctive stimulus, and pigeon's key pecks were reinforced by the occasional presentation of a 2-minute shock-free period. Extra 2-minute shock-free periods were added independently of behavior. For each of three pigeons, response rate during shock-on periods declined with added shock-free periods; the more frequently the extra shock-free periods occurred the greater the decline in response rate. This outcome is predicted by extending the Law of Effect to include negative reinforcement.

Journal Article↗

PubMed1991

Effects of haloperidol on the multitrial partial reinforcement extinction effect (PREE): evidence for neuroleptic drug action on nonreinforcement but not on reinforcement.

Two experiments investigated the effects of haloperidol (0.1 mg/kg) on the partial reinforcement extinction effect (PREE). In experiment 1 two groups of rats were trained to run in a straight alley using six trials/day with an intertrial interval (ITI) of 5-8 min. The continuously reinforced (CRF) group received food reward on every trial. The partially reinforced (PRF) group was rewarded on a quasi-random 50% schedule. All animals were then tested in extinction. Haloperidol was administered in a 2 x 2 design, i.e., drug-no drug in acquisition and drug-no drug in extinction. In experiment 2 two groups of rats were trained to press a lever in an operant chamber using a discrete trial procedure of ten trials/day with an ITI of 60 s. The CRF group was rewarded on each trial and the PRF group was rewarded on a quasi-random 50% schedule. Haloperidol was administered for 22 days prior to the start of the PREE procedure as well as throughout acquisition and extinction. The PREE, i.e., increased resistance to extinction of PRF as compared to CRF animals, was obtained in both experiments in all drug conditions. In both experiments haloperidol increased the rate of extinction. Experiment 1 revealed that this effect was entirely due to the administration of the drug in extinction, independently of the drug condition in acquisition. In contrast to previous results in a one trial/day procedure, the administration of haloperidol to CRF animals did not increase resistance to extinction, failing to support the notion that neuroleptics attenuate the rewarding properties of reinforcement.

Animals↗

PubMed1992

Oral self-administration of pentobarbital by rhesus monkeys: relative reinforcing effects under concurrent signalled differential-reinforcement-of-low-rates schedules.

During daily 3-h sessions two separate pentobarbital solutions were concurrently available to rhesus monkeys under signalled differential-reinforcement-of-low-rates (signalled DRL) schedules of mouth contacts with spouts. The schedules were synchronized so that each time the 30-s DRL interval expired, lights above both spouts were illuminated and a liquid delivery could be obtained either from the left or right spout, but not both. First water and then each of four 'comparison-concentration' pentobarbital solutions (0.0625, 0.25, 1 and 4 mg/ml) were successively available under one schedule for a block of sessions. Concurrently, deliveries of a 'standard concentration' solution were available from the second spout under an identical DRL schedule; the concentration of this standard solution remained constant throughout the testing of the series of comparison solutions. Three pentobarbital concentrations (4, 1 and 0.25 mg/ml) in turn served as the standard concentration. Relative reinforcing effects were directly related to pentobarbital concentration: in general, within pairs of concurrently available pentobarbital solutions more behavior was maintained by the higher of the two drug concentrations. These findings are discussed in the context of previous studies using ratio and interval schedules which have found relative reinforcing effects to be directly related to reinforcer magnitude.

Administration, Oral↗