Water Reinforcement Research Articles

Behavior of chicks exposed to low‐power 450‐MHz fields sinusoidally modulated at EEG frequencies

As part of an integrated series of experiments designed to provide a comprehensive picture of the behavior chicks exposed to 450‐MHz fields that are modulated at EEG frequencies, a total of 24, 23‐hour‐water‐deprived chicks, ∼ 12‐day post‐hatch at the beginning of the experiment, were exposed to 3‐ and 16‐Hz amplitude‐modulated fields at a power density of 1 or 5 mW cm−2 (n = 12) while performing on a fixed‐time 30‐second (FT‐30) schedule of water reinforcement. Reinforcments were in no way dependent on the subject's behavior and were delivered every 30 s for a 2‐s period. (Training on an FT schedule leads to an increase in the amount and temporal regularity of motor activity that occurs between successive reinforcements.) Sessions were divided into three 40‐reinforcment epochs: the first and third epochs were used as control periods (the field was never presented), while the middle epoch was that during which sham exposures or exposures to the field occurred. Computer analyses of the recorded interim behavior revealed possible differences in the temporal distributions of motor activity as a function of the exposure condition, but an analysis of variance performed on the mean latencies of activity counts showed that the differences were not statistically significant.

Counterconditioning of shock by a water reinforcer in rabbits

Three experiments studied the counterconditioning of certain properties of eyeshock in rabbits by establishing the shock as an appetitive CS for a jaw-movement response reinforced by intraoral water injections in a Pavlovian conditioning procedure. Although Experiment 1 demonstrated that such appetitive conditioning did not attenuate the unconditioned eyeblink elicited by the shock, it reduced the capacity of the shock to suppress leverpress responses reinforced by direct water injections in a signaled punishment procedure in Experiment 2. By contrast, when instrumentally reinforced licking was punished by eyeshock in Experiment 3, no such reduction in the suppressive capacities of the shock was found. The results were considered in terms of whether counterconditioning alters the response-eliciting or motivational and reinforcing properties of the shock.

Behavioral contrast and type of reward: Role of elicited response topography

Groups of pigeons were exposed to multiple variable-interval variable-interval and multiple variable-interval extinction schedules of either food or water reinforcement for keypecking. Discriminative stimuli associated with component schedules were located either on the operant key or on a second “signal” key. When the stimuli were projected on the operant key, positive contrast appeared during discrimination conditions with either food or water as the reinforcer. When the stimuli were projected on the signal key, overall responding to the operant and signal keys showed contrast with food, but negative induction with water as the reinforcer. In the latter condition, the signal for the variable-interval shcedule of water reinforcement elicited a variety of water-related behavior, only some of which was directed at the signal. Thus, the type of reward and location of discriminative stimuli interacted to determine the presence or absence of behavioral contrast effects. In large part, these results support and extend the autoshaping view of contrast.

Effects of clozapine and chlorpromazine upon operant response measures in rats

Rats responded under a FR20 schedule of water reinforcement by paw-pressing a silent, isometric, force-sensing manipulandum. Two seven-animal groups differed in terms of the force requirement for reinforcer delivery, i.e., a low-force condition (4-g requirement for reinforcer delivery) or a high-force condition (32-g requirement for reinforcer delivery). Oral dose ranges of chlorpromazine (1.0, 3.0, 9.0 mg/kg) and clozapine (2.5, 5.0, 10.0 mg/kg) were evaluated for their effects on intensive measures of response (i.e., peak force and duration), in addition to the conventional rate measure. Peak force, duration, and rate of response were recorded with a laboratory computer system. Conjoint examination of these three dependent variables revealed the clozapine, a new anti-psychotic agent which produces virtually no extrapyramidal side effects in man, affected FR responding in the same way as did chlorpromazine. More specifically, response rate and peak force declined as a function of dose for each drug. Duration of response tended to be increased at the highest dose for both clozapine and chlorpromazine, but this effect was limited primarily to the high-force condition.

Behavior of rats with septal lesions during low levels of water deprivation

The purpose of the present experiment was to investigate why rats with septal lesions show reduced response rates for water, compared to control rats, when the level of water deprivation is low. Two alternative explanations were tested experimentally: Caplan's (1973, Behavioral Biology , 9 , 129–167) “relativist” hypothesis and a “changed-motivation” hypothesis. The predictions from the two hypotheses were tested using a procedure in which the baseline was a variable-interval schedule of water reinforcement and several water-deprivation levels were used. In addition to lever presses for water, the following responses were recorded: Responses on a second lever which were reinforced by onset of the cue lights above this lever, and amount of time the rat spent in the part of the cage where there were no levers. The results showed that following septal lesions the rats were hypoactive when little deprived: In addition to reduced rate of lever pressing for water and reduced rate of water reinforcements, the rats stopped moving to the part of the cage where there were no levers and had an extremely low rate of lever pressing for light onset. These results were in accordance with the changed-motivation hypothesis; rats with septal lesions were hypomotivated when the level of water deprivation was low.

Interoceptive conditioning through repeated suppression of morphine-abstinence

The reinforcing properties of etonitazene, both conditioned and unconditioned, were measured in rats that had received saline only by continuous intravenous infusion (“saline” group) and in two groups of rats that had been physically dependent on morphine to equal degrees (and presumably had developed equal degrees of tolerance to morphine): one by once daily passive intravenous injection of morphine (“injection” group) and the other by passive continuous intravenous morphine infusion at the same daily doses for approximately the same number of days (“infusion” group). Prior to passive saline and morphine administration, all rats were trained to press right and left-sided levers for water reinforcement from 1600 to 0800 hrs to a not more than 60–40 split, and these and other measures (“baselines”) were repeated after recovery from the early (acute) morphine-abstinence syndromes. Then etonitazene, 5 μg/ml, was substituted for water on the nonpreferred side and all measures were repeated from 1600 to 0800 hrs once every two weeks for 20 weeks (10 “relapse” tests). It was postulated that the daily cycles of morphine-abstinence and suppression of abstinence in the injection group only would generate latent interoceptively conditioned reinforcing properties of morphine because of conditioning of suppression of abstinence to the concomitant internal sensorial effects of morphine, which would persist after morphine withdrawal and be transferred to the internal effects of another opioid, etonitazene. It was found that across the first nine relapse tests, the injection group consumed significantly more etonitazene than the infusion group, while there were no significant differences in water consumption. Also, the number of response-contingent etonitazene drinking tube presentations in the first 30 min period of lever availability in the first relapse test (when the unconditioned reinforcing effects and other pharmacological actions of etonitazene were minimal) was significantly greater for the injection group than for either the infusion or saline group, whereas there were no significant differences among the three groups in response-contingent water tube presentations. These findings support the interoceptive conditioning hypothesis.

Interoceptive conditioning through repeated suppression of morphine-abstinence. II. Relapse-testing.

The reinforcing properties of etonitazene, both conditioned and unconditioned, were measured in rats that had received saline only by continuous intravenous infusion ("saline" group) and in two groups of rats that had been physically dependent on morphine to equal degrees (and presumably had developed equal degrees of tolerance to morphine): one by once daily passive intravenous injection of morphine ("injection" group) and the other by passive continuous intravenous morphine infusion at the same daily doses for approximately the same number of days ("infusion" group). Prior to passive saline and morphine administration, all rats were trained to press right- and left-sided levers for water reinforcement from 1600 to 0800 hrs to a not more than 60-40 split, and these and other measures ("baselines") were repeated after recovery from the early (acute) morphine-abstinence syndromes. Then etonitazene, 5 micrograms/ml, was substituted for water on the nonpreferred side and all measures were repeated from 1600 to 0800 hrs once every two weeks for 20 weeks (10 "relapse" tests). It was postulated that the daily cycles of morphine-abstinence and suppression of abstinence in the injection group only would generate latent interoceptively conditioned reinforcing properties of morphine because of conditioning of suppression of abstinence to the concomitant internal sensorial effects of morphine, which would persist after morphine withdrawal and be transferred to the internal effects of another opioid, etonitazene. It was found that across the first nine relapse tests, the injection group consumed significantly more etonitazene than the infusion group, while there were no significant differences in water consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Methylphenidate and d-amphetamine: effects and interactions with alphamethyltyrosine and tetrabenazine on DRL performance in rats.

The effects of d-amphetamine and methylphenidate and their interactions with amine-depleting drugs were examined in rats trained to press a lever to obtain water reinforcement on a schedule that differentially reinforced responding at low rates (DRL). Both methylphenidate (2.5-20.0 mg/kg) and d-amphetamine (0.375-3.0 mg/kg) increased the rate of responding and decreased the frequency of reinforcement on the DRL schedule. Both drugs also shifted the interresponse time (IRT) distributions to the left such that the modal IRT occurred well below the minimum IRT required for reinforcement (d-amphetamine was abut eight times more potent than methylphenidate for each of these effects). The effects of both d-amphetamine and methylphenidate on DRL performance were attenuated by administration of alphamethyltyrosine (AMT) (150 mg/kg) and both drugs attenuated the response rate-suppressing effects of tetrabenazine (TBZ) (4.0 mg/kg). The similarity of the drug interactions between methylphenidate or amphetamine and AMT or TBZ suggest that the doses of methylphenidate and d-amphetamine examined act on similar catecholaminergic pools with the central nervous system to influence DRL performance.

RESPONDING MAINTAINED UNDER FIXED‐INTERVAL AND FIXED‐TIME SCHEDULES OF ELECTRIC SHOCK PRESENTATION1

Following initial histories under a schedule of electric shock postponement, lever pressing in squirrel monkeys was maintained under fixed-interval and fixed-time schedules of electric shock presentation. No difference in either rate or pattern of responding was obtained when these schedules were presented as components of a multiple schedule. When they were presented singly for long periods of time, the fixed-interval schedule consistently maintained a higher response rate than the fixed-time schedule. The pattern of responding under both schedules was similar, typically consisting of a pause at the beginning of each interval followed by either a steady or a positively accelerating rate of responding. The results suggest that the response-shock dependency is of critical importance in the maintenance of high rates of responding under schedules of electric shock presentation, and support the general view that such responding may be conceptualized as operant behavior under control of many of the same variables that control responding under comparable schedules of food or water reinforcement.

Electrical self-stimulation of the brain: a model for the behavioral evaluation of toxic agents.

Rats implanted chronically with electrodes in the posterior lateral hypothalamus were trained to press levers in order to stimulate the brain electrically. Brief exposures to low oxygen concentrations reduced the lever pressing rate proportionately with the reduction in inspired oxygen. Similar reductions in self-stimulation rates could be observed in animals exposed to carbon monoxide or the organic solvent, trichloroethylene. Prolonged exposures of animals to hypoxia in chambers where self-stimulation rates as well as food and water intake via lever pressing were monitored, indicated that as oxygen concentration declined self-stimulation rates showed a marked increase for 12 hr followed by a decline. Food and water intake were depressed. This increase in self-stimulation was only observed at low (20 degrees C) ambient temperatures and was accompanied by central depletion of norepinephine. At high (30 degrees C) ambient temperatures, self-stimulation was depressed by hypoxia. The data show the importance of comparing acute with chronic exposure to toxic agents, as well as the influence of environmental temperature in influencing behavioral events. In addition, the data indicate that the self-stimulation technique offers unique advantages over behavior maintained by food or water reinforcers in evaluating toxic compounds.

Suppression of fixed-interval responding by flavour-amphetamine pairings in rats

Amphetamine is a potent and very effective drug for conditioning taste aversions, but much less is known about the possible effects of flavour-amphetamine pairings on aspects of behaviour other than eating and drinking. Rats were trained to press bars for water reinforcers delivered on a fixed-interval one-min schedule. Flavoured reinforcers were then substituted for the water and post-session injections of amphetamine (1 mg/kg) were given. Even a single flavour-amphetamine pairing produced some disruption of responding for that flavour, whereas 3 pairings almost completely suppressed responding (both bar-pressing and drinking). In the same rats, flavours paired with saline injections did not suppress responding. Amphetamine (1 mg/kg) injected before sessions of responding for plain water disrupted the temporal pattern of fixed interval responding without affecting the total numbers of bar-presses or the amounts of liquid consumed. Omitting primary reinforcement (water) throughout a single session also failed to suppress responding. The conditioned effects of the flavour were therefore different from the effects of either the unconditioned stimulus (amphetamine) or of an extinction procedure.

Priming effects with food and water reinforcers in hamsters

Hamsters were tested in a square maze with either food or water in each corner compartment. A substantial priming effect (runway times increase as intertrial interval increases) was demonstrated using both food and water reinforcers. A lengthy period of free access to food and water (satiation) immediately abolished the priming effect, although runway times in general remained relatively rapid for some time. Extinction of rapid runway times proceeded more slowly under food than under water deprivation. It is concluded that priming is a widespread phenomenon associated with the presentation of a reinforcing stimulus to an appropriately deprived animal.

Effect of pimozide on the improvement in learning produced by self-stimulation and by water reinforcement

When rats self-stimulate immediately after the training trial of an appetitive task their performance on a retention test is improved the next day. In the present study, this improvement was blocked by pretraining injections of pimozide, a dopaminergic blocker. In a second experiment, injections of pimozide retarded learning on the same task when the learning was reinforced by drinking water, but had no effect on learning which occurred in the absence of a reinforcer. The data made the hypotheses that the animal's behavior was a result of an action of pimozide on sensory or motor mechanisms, or that the drug produced state-dependent effects, highly unlikely. We concluded that neural systems involving dopamine mediate an effect of reinforcing events on behavior.

Amphetamine-induced taste aversion demonstrated with operant behaviour

Amphetamine can be used to condition strong taste aversions, but little is known about the possible effects of flavour-amphetamine pairings on operant behaviour. Rats were trained to press bars for water reinforcers delivered after every 40 responses (FR 40). Flavoured reinforcers were then substituted for the water and post-session injections of amphetamine (1 mg/kg) were given. Even a single flavour-amphetamine pairing produced some decrement in responding for that flavour, whereas three flavour-amphetamine pairings almost completely suppressed responding. In the same rats, a flavour which was paired with saline injections did not suppress responding. Flavour-amphetamine pairings can therefore have a powerful influence on operant behaviour and the different outcomes of flavour-conditioning and self-administration procedures cannot be attributed simply to the type of response required from the rat.

The effects of scopolamine on extinction and spontaneous recovery

The effects of scopolamine hydrobromide on baseline extinction levels and spontaneous recovery were assessed. Rats were trained on one of four reinforcement schedules (CRF, FR 10, FR 20, FR 40) with either food or water reinforcement. Scopolamine increased response rates in extinction and spontaneous recovery following training on all four schedules when the reinforcer was water, but had no effect on responding previously maintained by food. The results are discussed in terms of the limitations of a general theory of a cholinergic system mediating all suppressed behavior and the effects of anticholinergic drugs on central thirst mechanisms and consummatory behavior.

A STUDY OF MISBEHAVIOR: TOKEN REINFORCEMENT IN THE RAT1

The purpose of this research was to investigate the phenomenon of misbehavior described by Breland and Breland (1961). Rats were trained to obtain ball-bearings and drop them in a hole for food or water reinforcers. In confirmation of the Brelands' observation, many subjects were slow to deliver the balls, and frequently attempted to chew them before they were dropped. A series of four experiments, in which the same rats were used throughout, showed that delivery times tended to be longer with food than with water, and that these times increased when nylon balls were substituted. The effect of motivational level was investigated by varying both deprivation and amount of prefeeding; no effect on delivery time was detected, although other measures of performance were affected by motivational factors. Similar results were obtained in a final experiment that employed a new set of naive subjects. The studies demonstrated that misbehavior can be studied in an experimental situation, and the results supported an analysis in terms of competition between stimulus-reinforcer and response-reinforcer contingencies. The question of why such effects have not been reported in previous token reinforcer studies was unanswered.

The effects of phencyclidine on operant behavior in the rat: Biphasic effect and tolerance development

Rats were trained to respond on a variable interval 60 sec (VI-60) schedule of water reinforcement. Phencyclidine (PCD) in doses of 0.25, 0.5, and 1.0 mg/kg i.p. increased response rates, respectively, to 118%, 140%, and 143% of the control rates. In contrast, doses of 2.0 and 4.0 mg/kg decreased response rates to 73% and 6% of the control rates. In the tolerance study, one group of rats received daily treatments of 4.0 mg/kg PCD immediately prior to the operant session, while a second group received the same daily dose of PCD after the operant session. When both groups of animals were treated prior to the operant session on a test day, they both displayed complete tolerance to the rate depressant effect of PCD. These results indicate that the observed tolerance to PCD was not dependent on behavioral compensatory mechanisms.

Effects of signaled and unsignaled brain stimulation, water, and sucrose reinforcement on running behavior in rats.

Effects of signaled and unsignaled brain stimulation, water, and sucrose reinforcement on running behavior in rats.

Within-Subject Analysis of the CS1-CS2 Interval in Sensory Preconditioning with Rats

Rats were trained to lever press on a variable-interval water reinforcement schedule prior to receiving sensory preconditioning (Spc) training, which consisted of 16 CS1-CS2 pairings followed by 16 CS2-footshock Us pairings and then by 10 Csralone trials. Magnitude of Spc was assessed by the amount of lever-press suppression to CS1 alone. Two distinct interstimulus intervals (Isis) between CS1 and CS2 were used with the relative proportion of each Isi varied across groups. Since mean Isi covaried with proportion, additional groups were exposed to fixed Isis of intermediate value. It was found that Spc magnitude increased directly with proportion to the more optimal Isi, although no differences were found between each proportion group and its fixed Isi counterpart.

Pharmacological and behavioral components of tolerance to LSD and mescaline in rats

A fixed-ratio schedule of water reinforcement (FR-10) was used to examine the relative contributions of pharmacological and behavioral mechanisms in the development of tolerance to the disruptive effects of LSD and mescaline in the rat. Rats treated daily with LSD or mescaline before operant testing developed tolerance to the impairment of responding, while rats treated daily after each session did not display tolerance when the drugs were administered before testing. These results indicate that behavioral compensatory mechanisms may be involved in the development of tolerance to the disruptive effects of LSD and mescaline on fixed-ratio (FR-10) performance.