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PubMed1978

Matching in concurrent variable-interval avoidance schedules.

After pretraining with multiple variable-interval avoidance schedules, two rats were exposed to a series of concurrent variable-interval avoidance schedules. Responses on two levers cancelled delivery of electric shocks arranged according to two independent variable-interval schedules. The ratio of responses and time spent on the two levers approximately matched the ratio of shocks avoided on each. Matching to the number of shocks received was not obtained. Concurrent variable-interval avoidance can therefore be added to the group of positive and negative reinforcement schedules that can be expressed in the quantitative framework of the matching law.

Journal Article↗
PubMed1963

Aversive aspects of a schedule of positive reinforcement.

Six male White Carneaux pigeons were trained to peck at one of two keys to obtain food on several fixed-ratio schedules of reinforcement. Concurrently, the first response on a second key could, I-change the conditions of visual stimulation and remove the food reinforcement contingency, II-change the conditions of stimulation and have no effect upon the reinforcement contingency, or III-do nothing. The second response on the stimulus change key always restored baseline conditions. When second-key responses produced a stimulus change, the number of such responses was a function of the ratio value on the first key. Typically, second-key responses occurred before the start of fixed-ratio runs. The duration of stimulus change periods was an exponential function of the number of responses required for reinforcement when the possibility for reinforcement was not disturbed by periods of stimulus change (Condition II).

Animals↗
PubMed1987

Intravenous self-administration of diazepam in rats.

Diazepam 0.5-2.0 mg/kg per injection was self-administered intravenously by rats on a continuous reinforcement schedule in a dose-dependent manner over a 30 day period. The rates of diazepam self-administration were relatively stable after responding was established, in comparison with rats self-administering morphine 0.5 mg/kg per injection whose rates continued to increase. At a fixed ratio 4 or 8 schedule, higher maximum rates of responding were seen with diazepam than with morphine. During withdrawal, reductions in body weight tended to occur in a manner dependent on the preceding rates of diazepam self-administration and were possibly caused by physical dependence. These findings suggest that diazepam acts as an intravenous reinforcer in rats and that the procedure we describe is of use to predict the dependence liability of drugs considered to have only a weak potential for abuse.

Animals↗
PubMed1983

Undermatching and overmatching as deviations from the matching law.

A model of performance under concurrent variable-interval reinforcement schedules that takes as its starting point the hypothetical "burst" structure of operant responding is presented. Undermatching and overmatching are derived from two separate, and opposing, tendencies. The first is a tendency to allocate a certain proportion of response bursts randomly to a response alternative without regard for the rate of reinforcement it provides, others being allocated according to the simple matching law. This produces undermatching. The second is a tendency to prolong response bursts that have a high probability of initiation relative to those for which initiation probability is lower. This process produces overmatching. A model embodying both tendencies predicts (1) that undermatching will be more common than overmatching, (2) that overmatching, when it occurs, will tend to be of limited extent. Both predictions are consistent with available data. The model thus accounts for undermatching and overmatching deviations from the matching law in terms of additional processes added on to behavior allocation obeying the simple matching relation. Such a model thus enables processes that have been hypothesized to underlie matching, such as some type of reinforcement rate or probability optimization, to remain as explanatory mechanisms even though the simple matching law may not generally be obeyed.

Journal Article↗
PubMed1976

Auditory frequency generalization with differing extinction influences in normal and prefrontal dogs trained in instrumental alimentary reflexes.

Following criterion of 90 percent correct responses to a 1,000-Hz tone on a 50 percent reinforcement schedule, 8 of 12 dogs were subjected to lesions of the medial or lateral prefrontal cortex. Three types of auditory frequency generalization tests followed separated by a period of reacquisition of the instrumental response. A sampling procedure of generalization assessment, wherein a block of test trials was contained within 15 partially reinforced trials and repeated over 16 days, revealed complete generalization in the medials and rapid, but discriminative responding in the laterals. The second generalization test was conducted in complete extinction over 5 days. The medials yielded discriminative performance and least overall resistance to extinction, while the laterals showed a higher amount of frequency control and minimal extinction effects. Go-no go differentiation training preceeded the last generalization test [CS(+) = 1,000 Hz; CS(-) = 600 Hz], resulting in retarded acquisition in the laterals and easiest acquisition in the medials. The last generalization test suggested that all groups were comparable, with some trend toward more rapid extinction in the medial dogs. Collectively, the data indicated that performance was determined by the interacting functions between the specific lesions and the density of reinforcement present in the testing procedure.

Animals↗
PubMed1967

Operant reinforcement of an autonomic response: two studies.

Two successive studies were conducted to determine the possibility of operant reinforcement of nonspecific galvanic skin resistance responses. In the first study, with five experimental and three control subjects who served for 20 to 30 min a day for 10 days, all experimental subjects learned to emit more nonspecific galvanic skin resistance responses than their ad hoc matched controls. In a second study, nine experimental and nine control subjects were matched for first-day levels of reactivity and yoked for operant reinforcement schedules. Significant differences between the two groups were found on the last day of conditioning and during extinction. Six of the nine experimental subjects showed higher cumulative rate curves than their matched and yoked controls. The concomitant measures (basal resistance, heart rate, etc.) all supported this finding. It was suggested that operant reinforcement of autonomic response tends to maintain a certain level of responding in contrast to persistent adaptation in the control group.

Journal Article↗
PubMed1975

Application of Premack's generalization of reinforcement to modify occupational behavior in two severely retarded individuals.

Premack's generalization that a more probable response will reinforce a less probable one was applied to modify occupational behavior of two severly retarded individuals. When opportunity to work on a more preferred activity was made contingent upon spending some time on a less preferred activity, an increase in the amount of time spent on less preferred work occurred. As the reinforcement schedule was gradually reduced in terms of time allowed on more preferred work, time spent on the less preferred activity tended to increase. Behavior did not return to baseline levels on extinction, however. Possible reasons for these findings are outlined, together with the practical advantages of utilizing Premack's generalization as a reinforcement technique for motivating retarded individuals in rehabilitation settings.

Adult↗
PubMed1975

Scopolamine effects on visual discrimination: modifications related to stimulus control.

Stumptail monkeys (Macaca arctoides) performed a discrete trial, three-choice visual discrimination. The discrimination behavior was controlled by the shape of the visual stimuli. Strength of the stimuli in controlling behavior was systematically related to a physical property of the stimuli, luminance. Low luminance provided weak control, resulting in a low accuracy of discrimination, a low response probability and maximal sensitivity to scopolamine (7.5--60 mug/kg). In contrast, high luminance provided strong control of behavior and attenuated the effects of scopolamine. Methylscopolamine had no effect in doses of 30 to 90 mug/kg. Scopolamine effects resembled the effects of reducing stimulus control in undrugged monkeys. Since behavior under weak control seems to be especially sensitive to drugs, manipulations of stimulus control may be particularly useful whenever determination of the minimally-effective dose is important, as in behavioral toxicology. Present results are interpreted as specific visual effects of the drug, since nonsensory factors such as base-line response rate, reinforcement schedule, training history, motor performance and motivation were controlled. Implications for state-dependent effects of drugs are discussed.

Animals↗
PubMed1968

Chlorpromazine: direct measurement of differential behavioral effect.

A retarded child with a high stereotyped rocking rate was conditioned to pull a ball on a reinforcement schedule in which the fixed ratio aof rewarded to nonrewarded responses was 100. Results show no rocking movements during ball-pulling; but when ball-pulling was on extinction, rocking returned to its original rate. Chlorpromazine blocked rocking movements during extinction, but had no effect on ball-pulling. Delivery of one free reinforcer was sufficient to reinstate ball-pulling after extinction, but the stimulus properties of the free reinforcer were not affected by the drug.

Adolescent↗
PubMed1993

Session duration and the VI response function: Within-session prospective and retrospective effects.

Two experiments examined the effects of session duration on responding during simple variable-interval schedules. In Experiment 1, rats were exposed to a series of simple variable-interval schedules differing in both session duration (10 min or 30 min) and scheduled reinforcement rate (7.5 s, 15 s, 30 s, and 480 s). The functions relating response rate to reinforcement rate were predominantly monotonic for the short (10-min) sessions but were predominantly bitonic for the long (30-min) sessions, when data from the entire session were considered. Examination of responding within sessions suggested that differences in the whole-session data were produced by a combination of prospective processes (i.e., processes based on events scheduled to occur later in the session) and retrospective processes (i.e., processes based on events that had already occurred in the session). In Experiment 2, rats were exposed to a modified discrimination procedure in which pellet flavor (standard or banana) predicted session duration (10 min or 30 min). All rats came to respond faster during the short (10-min) sessions than during the first 10 min of the long sessions. As in Experiment 1, the results seemed to reflect the simultaneous operation of both prospective and retrospective processes. The results shed light on the recent controversy over the form of the variable-interval response function by identifying one variable (session duration) and two types of processes (prospective and retrospective) that influence responding on these schedules.

Journal Article↗
PubMed1981

Base-line muscle tensions and motoric responding of schizophrenics.

Schizophrenics with high or low levels of frontalis muscle tensions while at rest (base-line) were instructed to respond (button-press) at different rates, allowed to respond at any rate they preferred, and reinforced for responding under different schedules of reinforcement. Information about response-reinforcement relationships was provided for each reinforcement schedule. High and low levels of base-line muscle tensions were associated with high and low rates of preferred and reinforced responding, respectively. Response rates also varied with different contingencies of reinforcement. Further, the data permit the following tentative conclusions: (a) under certain contingencies, responding may vary more with base-line muscle tensions than with the contingency of reinforcement, and (b) instructed rates of responding may not be correlated consistently with base-line muscle tensions.

Adult↗
PubMedDate not supplied

Schedule-controlled operant behavior of rats during 1,1,1-trichloroethane inhalation: relationship to blood and brain solvent concentrations.

The central nervous system is the principal target of 1,1,1-trichloroethane (TRI), and several studies of this volatile solvent have demonstrated effects on learned animal behaviors. There have been few attempts, however, to quantitatively relate such effects to blood or target organ (brain) solvent concentrations. Therefore, Sprague-Dawley rats trained to lever-press for evaporated milk on a variable interval 30-s reinforcement schedule were placed in an operant test cage and exposed to clean air for 20 min, followed by a single concentration of TRI vapor (500-5000 ppm) for 100 min. Additional rats were exposed to equivalent TRI concentrations for 10, 20, 40, 60, 80, or 100 min to determine blood and brain concentration vs. time profiles. Inhalation of 1000 ppm slightly increased operant response rates, whereas 2000, 3500, and 5000 ppm decreased operant response rates in a concentration- and time-dependent manner. Accumulation of TRI in blood and brain was rapid and concentration dependent, with the brain concentration roughly twice that of blood. Plots of blood and brain TRI concentrations against operant performance showed responding in excess of control rates at low concentrations, and decreasing response rates as concentrations increased. Linear regression analyses indicated that blood and brain concentrations, as well as measures of time integrals of internal dose, were strongly correlated with operant performance. Neurobehavioral toxicity in laboratory animals, as measured by changes in operant performance, can therefore be quantitatively related to internal measures of TRI exposure to enhance its predictive value for human risk assessment.

Animals↗
PubMed1985

Proactive behavioral effects of theta-driving septal stimulation on conditioned suppression and punishment in the rat.

In two experiments, a treatment phase of septal stimulation preceded the acquisition of free operant lever pressing on a random-interval 64-s reinforcement schedule. Male Sprague-Dawley rats, chronically implanted with a bilateral septal stimulating electrode and a unilateral bipolar hippocampal recording electrode, received (a) low-frequency (7.7-Hz) stimulation, which drove the hippocampal theta rhythm, or (b) random-pulse stimulation (average frequency = 7.7 Hz), which produced only nonregular waveforms in the hippocampus. Control animals were implanted but not stimulated. After 12 days of lever-press acquisition, animals were presented while lever pressing with an auditory signal associated with a particular schedule of shock delivery: In Experiment 1, shocks occurred despite the subject's response strategy; in Experiment 2, shocks were delivered only if the rat pressed the lever. In both experiments, lever pressing was suppressed by the auditory stimulus. Theta-driving but not random-pulse septal stimulation proactively increased behavioral tolerance to the effects of electric shock. These results reinforce the idea that proactive behavioral effects of septal stimulation are a consequence of the production of the hippocampal theta rhythm.

Animals↗
PubMed2006

Response perseveration and adaptation in heavy marijuana-smoking adolescents.

The present study examined two behavioral processes - response perseveration and response adaptation - in adolescents who were heavy marijuana smokers and control adolescents. Testing took place in a controlled laboratory setting, using customized software and either a computer keyboard or a custom built response panel for response input. Adolescents age 14-18 were recruited into a heavy smoking (near daily) group (N=22) or a control group (N=31) with <15 lifetime uses of marijuana and no history of substance abuse or dependence. Marijuana use was verified by daily quantification of urinary cannabinoids and self-reports. Participants completed laboratory tasks designed to measure response perseveration (Wisconsin Card Sort Task, WCST) and response adaptation (concurrent variable-ratio reinforcement schedule with changing contingencies). Data were analyzed via ANOVA, controlling for multiple factors including: gender, age, nicotine use, presence of conduct disorder, and subscales of the Youth Self Report. After controlling for these compared to controls marijuana-using participants made significantly more perseverative and total errors on the WCST and showed significantly impaired (e.g., less adaptive) response allocation to the changing reinforcement contingencies on the concurrent-reinforcement task. Within the constraints of the study's limitations in controlling for alternative sources of between-subject variability, the data suggest that individuals who regularly smoke marijuana during adolescence show measurable perturbations in important basic behavioral processes. The data are also consistent with a previous laboratory study demonstrating reduced motivation in marijuana-smoking adolescents versus controls [Lane, S.D., Cherek, D.R., Pietras, C.J., and Steinberg, J.L. (2005). Performance of heavy marijuana-smoking adolescents on a laboratory measure of motivation. Addictive Behaviors, 30, 815-828].

Adaptation, Psychological↗
PubMedDate not supplied

Prenatal ethanol effects on reward efficacy for adult mice are gestation stage specific.

We previously reported that adult mice exposed to ethanol throughout gestation (G5-17) responded slower than controls on reinforcement schedules which required large numbers of responses per unit of food, i.e., high fixed ratio (FR) schedules. The primary finding of the present study was that ethanol exposure during the last 5 days of gestation (G12-17) is sufficient to produce this effect whereas a similar exposure early in gestation (G5-10) is not. Both male and female mice exposed to ethanol late in gestation responded slower than either lab chow or pair-fed controls, and the effect was similar to that of mice exposed to ethanol throughout gestation (G5-17) in our earlier study. Thus, developmental events occurring late in gestation are important for the reduced reinforcing efficacy of food for prenatal-ethanol-exposed mice. In addition, the present experiment established the comparability of the sucrose and lab chow controls on this task. The results of the present study and our previous report are compatible with the hypothesis that the reduced responding on high FR schedules exhibited by prenatal-ethanol-exposed mice reflects a reduction in the efficacy of food reward. It is possible that the reduction in reward efficacy is due to altered development of neuronal systems functionally related to reward which develop late in gestation.

Animals↗
PubMed1998

Subicular lesion induced impairment in operant behaviour and altered dendritic morphology of CA1, CA3 hippocampal neurons.

The effects of bilateral electrolytic subicular lesions were examined on the operant behaviour for food reward on a continuous reinforcement schedule as well as the dendritic morphology of CA1 and CA3 hippocampal areas. The subjects were female Wistar rats 20 days of age and were divided into four groups. 1. Age matched control 2. Sham operated 3. Operant behaviour for food reward and 4. Subicular lesion. Animals were starved twenty-four hours prior to operant behaviour training sessions. Two trial sessions with continuous reinforcement (CRF) of 10 min duration/day were done during training sessions following which the rats were allowed CRF for ten minutes per day for ten days. On the eleventh day, the operant behaviour and sham operated animals were taken up for bilateral subicular lesion and sham surgery respectively. After seventy two hours of surgical recovery, operant behavioural testing was done as before for a further period of ten days. Later all the groups of animals were sacrificed and the hippocampi were processed for rapid Golgi staining technique. Our results suggest that subicular lesions do produce a significant reduction in operant learning behaviour for food reward. Further the Golgi studies revealed a reduction in dendritic branching points and intersections of apical and basal CA1, CA3 neurons in lesioned animals.

Animals↗
PubMed1985

Positive and negative reinforcement effects on behavior in a three-person microsociety.

Three-person groups, either of males or of females, resided for 6 to 12 days in a continuously programmed environment. Subjects followed a behavioral program that determined the sequential and contingent relations within an inventory of activities. The program consisted of positive reinforcement days and avoidance days. During a positive reinforcement day, each work unit completed by a subject incremented a group account. The account was divided evenly among the three participants at the conclusion of the study. During a negative reinforcement day, no money was earned, and the group was assigned work unit criterion that, if completed, prevented a reduction in accumulated earnings. During negative reinforcement days, subjects made aggressive verbal responses, which differed in magnitude among the four groups. These differences were evident in several distinct behavioral measures. Performances on components of the work unit were not demonstrably affected by the reinforcement schedules in effect, although during the avoidance condition one subject stopped working and another subject's productivity declined.

Adolescent↗
PubMed1994

Establishing benzodiazepines as oral reinforcers: midazolam and diazepam self-administration in rhesus monkeys.

Oral benzodiazepine self-administration was examined in four adult male rhesus monkeys with histories of ethanol- and pentobarbital-reinforced behavior. Drug solutions and vehicle were concurrently available for 3-hr each day under fixed-ratio (FR) reinforcement schedules. Initially, the monkeys rejected a midazolam solution (0.1 mg/ml) after direct substitution of the drug for an 8% ethanol solution. However, midazolam self-administration was subsequently established by using a fading procedure in which increasing amounts of drug (0.0125-0.2 mg/ml) were gradually added to an 8% ethanol solution, followed by gradual reduction of the ethanol concentration to zero. Midazolam was an effective reinforcer for three of four monkeys tested, i.e., responding that was maintained by the drug solution exceeded that maintained by the drug vehicle. The fourth monkey also self-administered midazolam but drug-maintained responding was not consistently greater than vehicle-maintained responding. The responding maintained by the drug was an inverted-U-shaped or bitonic function of midazolam concentration. The midazolam intake (in milligrams per kilogram) increased as a function of increases in the drug concentration. At the higher concentrations, marked sedative intoxication was observed. There was an inverse relationship between FR size (varied from FR 8 to FR 32) and the amount of drug self-administered. The three monkeys in which midazolam functioned as a reinforcer were then tested with diazepam (0.2 mg/ml), which maintained drug self-administration behavior on direct substitution for 0.2-mg/ml midazolam. Diazepam-maintained responding usually exceeded water responding as the diazepam concentration was increased to 0.8 mg/ml. These data demonstrate robust reinforcing effects of both "short-" and "long-acting" benzodiazepines delivered by the oral route.

Administration, Oral↗