PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Reinforcement Schedule”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1995

Effect of medial prefrontal cortex injections of SCH 23390 on intravenous cocaine self-administration under both a fixed and progressive ratio schedule of reinforcement.

Rats were trained to self-administer cocaine (1.5 mg/kg i.v.) under either a fixed ratio (FR) or progressive ratio (PR) schedule of reinforcement. Following acquisition, bilateral intracerebral cannulae were directed at the medial prefrontal cortex (mPFC) or striatum (STRM). Intracranial injections of the D1 receptor antagonist, SCH 23390 (0-2.0 micrograms/0.5 microliter/side), were made immediately prior to a self-administration session. Under the FR 1 schedule, SCH 23390 caused a dose-dependent increase in the rate of cocaine intake following injection into either the mPFC or the STRM. In contrast, under the PR schedule similar injections into the STRM had no effect on the breaking point, but large decreases were produced following injection into the mPFC. These results indicate that dopaminergic systems within the mPFC have a significant role to play in the reinforcing properties of cocaine. Moreover, the STRM does not appear to have a role in those reinforcing properties of cocaine measured under the PR schedule. The significant rate-increasing effects obtained from the STRM under the FR schedule, indicate that the two schedules must measure different aspects of cocaine's CNS action.

Animals↗
PubMed1981

Increasing slowed operant responding of schizophrenics under a fixed-ratio schedule of reinforcement.

Two procedures were evaluated in terms of their ability to modify the slowed responding of schizophrenics under an FR 40 schedule. FR 40 response rates increased when schizophrenics were instructed to earn a minimum number of reinforcements or to imitate the rate of responding of someone shown earning that minimum number of reinforcements. The greater increase in FR 40 responding occurred under the latter procedure.

Conditioning, Operant↗
PubMed1988

Application of operant procedures in a group of institutionalized aggressive geriatric patients.

This study used positive reinforcement schedules versus no reinforcement on a group of 6 highly aggressive, institutionalized elderly patients. Dependent measures included confirmed incidents of physical and verbal aggressive behavior monitored across an ABAB design with a 4-month phase-out period. Results indicated that aggressive behavior can be significantly decreased in a group setting and subsequently generalized to ward behavior. Ancillary aspects of the study included the role of tangible and back-up reinforcers and staff attitude and behavior. Implications for future research are discussed.

Aged↗
PubMed1967

Time-dependent contrast effects in a multiple schedule of food reinforcement.

Four rats were rewarded for running in a wheel under two alternating conditions of food reinforcement. These periods of frequent and infrequent reinforcement, each accompanied by a particular stimulus, were presented a number of times in each daily session. Following shifts from high to low frequency of reinforcement, responding decreased suddenly and markedly, and then recovered within the next few minutes. The magnitude of this temporary depression was an increasing function of the duration of the immediately preceding component of high-frequency reinforcement. A transient elevation in performance, which did not vary with the duration of the prior component, was noted in two subjects following shifts from low to high frequency of reinforcement. The elevation and depression effects did not appear simultaneously during the 48 experimental sessions. A possible relation between the difficulty of the discrimination and the extent of contrast effects is discussed.

Animals↗
PubMed2002

Dopamine release in the dorsal striatum during cocaine-seeking behavior under the control of a drug-associated cue.

Compulsive drug use is characterized by a pattern of drug seeking and consumption that becomes progressively habitual and less and less modifiable by external and internal factors. Although traditional views would posit that nigrostriatal dopamine (DA) neurons originating in the substantia nigra and innervating the dorsal striatum are primarily concerned with motor functions, recent studies have implicated the dorsal striatum in mediating stimulus-response (habit) learning. In this study, in vivo microdialysis in combination with a second-order schedule of cocaine reinforcement was used to investigate the role of the dorsal striatal dopamine innervation in well established drug-seeking behavior under the control of a drug-associated cue [light conditioned stimulus (CS+)]. Rats were initially trained to self-administer cocaine under a continuous reinforcement schedule where a response on one of two identical levers led to a 20 sec presentation of a light CS+ and an intravenous cocaine infusion (0.75 mg/kg). The response requirement for the CS+ and cocaine was then progressively increased until stable responding was established under a second-order schedule of reinforcement. During microdialysis, rats were presented with the cocaine-associated CS+ either noncontingently or contingent on responding during a session of cocaine-seeking behavior. The results showed a marked increase in DA release in the dorsal striatum during drug-seeking, when cocaine cues were presented contingently, but not when the same cue was presented noncontingently. These data indicate a possible involvement of the dopaminergic innervation of the dorsal striatum in well established, or habitual, cocaine-seeking behavior.

Animals↗
PubMed2003

Beta-funaltrexamine affects cocaine self-administration in rats responding on a progressive ratio schedule of reinforcement.

Many studies have shown interactions between mu-opiates and the mesolimbic dopamine (DA) system. Mu-opiate receptor antagonists have been reported to either increase or decrease the rate of cocaine self-administration, and the interpretation of these data has been difficult. In an attempt to further characterize and localize the effect of opiate receptor blockade on the reinforcing effects of cocaine, the mu-opiate irreversible antagonist beta-funaltrexamine (betaFNA) was administered locally to different regions of the mesocorticolimbic system. Microinjection of betaFNA into the ventral tegmental area (VTA) or the nucleus accumbens (NAcc) had no effect on cocaine self-administration under a fixed ratio (FR) schedule of reinforcement. However, blockade of opiate receptors in both brain regions did attenuate responding for cocaine maintained by a progressive ratio (PR) schedule. Administration of betaFNA in the dorsal striatum had no effect under either schedule condition. The present findings suggest that endogenous opiate systems within the mesolimbic DA system modulate the reinforcing effects of cocaine; however, this modulation seems to be schedule dependent.

Animals↗
PubMed1993

Dopaminergic antagonism within the nucleus accumbens or the amygdala produces differential effects on intravenous cocaine self-administration under fixed and progressive ratio schedules of reinforcement.

Bilateral intracerebral injections of the D1 receptor antagonist, SCH 23390, were administered into the nucleus accumbens (NACC) or amygdala (AMY) immediately prior to an i.v. cocaine self-administration session. Injection into both sites produced a dose-dependent (0.1-2.0 micrograms/injection) increase in the rate of cocaine self-administration under a fixed ratio (FR) schedule of reinforcement (1.5 mg/kg/injection). However, injection into the AMY produced a significantly greater increase in rate of drug intake than within the NACC. In contrast, under a progressive ratio (PR) schedule of cocaine reinforcement the D1 antagonist had very little effect within the AMY on break point (BP) but greatly reduced the BP following injection into the NACC. A locomotor activity study revealed that following systemic injection of cocaine (10 mg/kg i.p.), SCH 23390 (1.0 microgram/injection site) significantly reduced activity to comparable levels following injection into either brain site. This indicates that the dissociation of effects between the two neural sites within the cocaine self-administration paradigm does not appear to be due to greater locomotor reducing actions of the antagonist within the NACC. These results demonstrate that a significant contribution is made by AMY dopamine to cocaine reinforcement mechanisms, which appears to be different to that of the NACC. Moreover, they suggest that FR and PR schedules may measure different aspects of cocaine's CNS action which support self-administration behaviour.

Amygdala↗
PubMed1998

Effects of pedunculopontine tegmental nucleus lesions on responding for intravenous heroin under different schedules of reinforcement.

The pedunculopontine tegmental nucleus (PPTg) is believed to play important roles in reward and learning. We examined the effect of PPTg lesions (0.5 microl of 0.1 M NMDA injected bilaterally over 10 min) on the learning of an operant response for opiate reward. In 14 adult male Long-Evans rats, bilateral lesions of the PPTg disrupted the acquisition of responding for intravenous heroin (0.1 mg/kg infused at a rate of 0.25 ml/28 sec) on a fixed ratio-1 (FR-1) schedule of reinforcement. The 12 remaining lesioned animals increased their heroin intake over the acquisition sessions but did not reach the response levels of sham-lesioned animals on the 15th and final session. The sham- and PPTg-lesioned animals that learned the FR-1 task exhibited similar patterns of responding during extinction and reacquisition sessions. When tested on a progressive ratio (PR) schedule of reinforcement, however, PPTg-lesioned animals had lower break points than sham-lesioned animals. Asymmetric lesions, which destroyed the majority of the nucleus in one hemisphere only, did not produce any behavioral deficits. Rats that were lesioned after training also did not show deficits in responding under either FR or PR schedules. These findings suggest that PPTg lesions reduce the rewarding effect of opiates but do not disrupt the ability either to learn an operant response or the response requirements of a PR schedule.

Animals↗
PubMed1974

Conjunctive schedules of reinforcement. I. Rate-dependent effects of pentobarbital and d-amphetamine.

Key pecking of pigeons was maintained under conjunctive schedules of food presentation in which both a fixed-interval and a fixed-ratio schedule had to be completed before a peck produced food. For two pigeons, pecks on a single key completed both schedule requirements (fixed-interval 3-min, fixed-ratio 50 for one bird, fixed-interval 5-min, fixed-ratio 50 for the second). For two other pigeons, each requirement was scheduled on a separate key. On the two-key schedule, a peck after 5 min on the key scheduling the fixed-interval requirement produced food if at least 10 pecks had occurred on the ratio key (conjunctive fixed-interval 5-min, fixed-ratio 10). When each requirement was scheduled on a separate key, response rates on the fixed-ratio key were generally higher in the early portion of the interval and declined as the interval progressed; responding on the fixed-interval key, once initiated, typically remained at a constant rate throughout the interval. Responding under the single-key schedule was characterized by a high rate early in the interval; this then changed to a lower rate that continued until a peck produced food. For all pigeons, increases in response rates with pentobarbital and d-amphetamine were inversely related to the control rate of responding. When equivalent rates on each key of the two-key schedule were compared, both drugs increased rates on the fixed-ratio key less. Although the effects of both drugs were rate dependent, each drug differentially modified the pattern of responding under the single-key schedule.

Animals↗
PubMed2006

Investigations of timing during the schedule and reinforcement intervals with wheel-running reinforcement.

Across two experiments, a peak procedure was used to assess the timing of the onset and offset of an opportunity to run as a reinforcer. The first experiment investigated the effect of reinforcer duration on temporal discrimination of the onset of the reinforcement interval. Three male Wistar rats were exposed to fixed-interval (FI) 30-s schedules of wheel-running reinforcement and the duration of the opportunity to run was varied across values of 15, 30, and 60s. Each session consisted of 50 reinforcers and 10 probe trials. Results showed that as reinforcer duration increased, the percentage of postreinforcement pauses longer than the 30-s schedule interval increased. On probe trials, peak response rates occurred near the time of reinforcer delivery and peak times varied with reinforcer duration. In a second experiment, seven female Long-Evans rats were exposed to FI 30-s schedules leading to 30-s opportunities to run. Timing of the onset and offset of the reinforcement period was assessed by probe trials during the schedule interval and during the reinforcement interval in separate conditions. The results provided evidence of timing of the onset, but not the offset of the wheel-running reinforcement period. Further research is required to assess if timing occurs during a wheel-running reinforcement period.

Analysis of Variance↗
PubMed1976

Morphine, pentazocine and naloxone effects on responding under a multiple schedule of reinforcement in rhesus monkeys and pigeons.

The effects of morphine, pentazocine, naloxone and combinations of these drugs on schedule-controlled behavior were examined in rhesus monkeys and pigeons. The order of potency in decreasing response rates under a multiple 5-minute fixed-interval, 30-response fixed-ratio schedule in both monkeys and pigeons was morphine greater than pentazocine greater than naloxone. Compared to monkeys, pigeons were less sensitive to morphine and pentazocine and slightly more sensitive to naloxone. In monkeys and pigeons, as the morphine dose increased, higher naloxone doses were required to restore responding to or near control levels. In pigeons, however, the response rate decreases caused by naloxone prevented the complete antagonism of the highest morphine dose and limited the range of naloxone doses over which complete antagonism of morphine occurred. Antagonism of pentazocine by naloxone generally was greatest at the lowest pentazocine dose tested in both monkeys and pigeons. At higher pentazocine doses, if any antagonism was obtained, it was slight, and the amount of antagonism typically did not increase as the naloxone dose increased. Pentazocine generally failed to antagonize morphine in monkeys and pigeons.

Animals↗
PubMed2001

Choices between positive and negative reinforcement during treatment for escape-maintained behavior.

Positive reinforcement was more effective than negative reinforcement in promoting compliance and reducing escape-maintained problem behavior for a child with autism. Escape extinction was then added while the child was given a choice between positive or negative reinforcement for compliance and the reinforcement schedule was thinned. When the reinforcement requirement reached 10 consecutive tasks, the treatment effects became inconsistent and reinforcer selection shifted from a strong preference for positive reinforcement to an unstable selection pattern.

Autistic Disorder↗
PubMed1968

Fixed-ratio punishment by timeout of concurrent variable-interval behavior.

Pigeons' responding was maintained by two concurrently available variable-interval reinforcement schedules. A fixed-ratio punishment schedule of timeout periods from the concurrent reinforcement schedules was arranged for responding during one of the variable-interval schedules. The greater the probability of a timeout after a response on the punished variable-interval schedule (the smaller the fixed ratio that produced timeout), the greater the decline in the relative punished response rates. Relative reinforcement rates remained invariant when relative response rates declined. Both behavioral contrast and induction effects were observed on the unpunished variable-interval schedule as a function of timeout punishment of the other schedule.

Animals↗
PubMed1994

Human choice in concurrent ratio-interval schedules of reinforcement.

Seven undergraduates participated in a concurrent-choice experiment with monetary reinforcers. Response-independent analogues of variable-interval and variable-ratio schedules were used to assess whether subjects would maximize reinforcement rate. The optimal pattern of behavior, in terms of maximizing reinforcement rate, involved a large bias toward the ratio alternative, with only occasional sampling of the interval schedule. Most experiments with pigeons, however, demonstrate matching of response rates to reinforcement rates, with only slight biases for the ratio schedule. Although subjects in the present experiment allocated more time to the ratio alternative than required by matching, the magnitude of the bias did not approximate that predicted by a maximizing account. After exposure to clock stimuli correlated with the operation of each schedule, 1 subject's behavior did show a substantial level of bias, increasing the total number of reinforcers obtained, and lay at a point between the predictions of matching and maximizing. The other subjects, however, continued to respond less optimally. The present results can be accounted for by a view of matching that incorporates the effects of delayed reinforcement.

Choice Behavior↗
PubMed1991

Effects of d-amphetamine on responding under second-order schedules of reinforcement with paired and nonpaired brief stimuli.

Three pigeons were studied under a multiple schedule in which pecks in each component were reinforced according to a variable-interval 120-s second-order schedule with fixed-interval 60-s units. In the first component of the multiple schedule, the completion of a fixed interval produced either food or a 4-s change in key color plus houselight illumination. In the second component an identical schedule was in effect, but the stimulus was a 0.3-s change in key color. Both long and short brief stimuli were not paired with food presentations in Conditions 1 and 3 and were paired with food in Condition 2. There were no consistent differences in response patterns under paired and nonpaired brief-stimulus conditions when the stimulus was a 4-s change in key color accompanied by houselight illumination. However, pairing the 0.3-s key-color change with food presentations resulted in higher indices of curvature and lower response rates in the early segments of the fixed interval than when the stimulus was not paired with food presentations. Low doses of d-amphetamine (0.3 and 1 mg/kg) produced small and inconsistent increases in overall response rates, and higher doses (3 and 10 mg/kg) decreased overall response rates. d-Amphetamine altered response patterns within fixed intervals by decreasing the indices of curvature and increasing response rates in the early segments of the fixed interval. Response rates and patterns under paired and nonpaired brief-stimulus conditions were not differentially affected by d-amphetamine. Thus, evidence for the enhancement of the conditioned reinforcement effects of psychomotor stimulant drugs was not found with the second-order schedules used in the present study.

Animals↗
PubMed1971

Sequence schedules of reinforcement.

The performance of pigeons was studied under a second-order schedule composed of fixed-interval components, each of which was associated with a different discriminative stimulus, the stimuli occurring in a fixed order. In one condition, food presentation followed the completion of the fourth component. This was designated a fixed-ratio sequence schedule. In another condition, responses in the first component completed after a fixed time were reinforced. This was designated a fixed-interval sequence schedule. Although the stimulus order and maximum reinforcement frequency were identical under the two schedules, considerably more responding occurred under the fixed-interval sequence schedule in all components. Relatively few food presentations occurred after responding during any but the terminal components of the fixed-interval sequence schedule, a feature independent of the parameter values investigated. In addition, while a pattern of increased responding between food presentations prevailed under both schedules, under the fixed-interval sequence schedule the rate in the terminal component was frequently less than in the penultimate component. The fixed-interval sequence schedule appeared to have several properties of simple fixed-interval schedules.

Journal Article↗