Effects of weekly exposure to anatoxin-a and nicotine on operant performance of rats.

This study examined the effects of acute and weekly administration of anatoxin-a and nicotine on operant performance. Anatoxin-a is a potent nicotinic receptor agonist produced by cyanobacteria, which are found in fresh waters throughout the world. Anatoxin-a is a potential human health hazard and has been responsible for numerous deaths of wildlife, livestock and domestic animals. Remarkably little is known, however, about the effects of anatoxin-a on behavior. Nicotine, the psychomotor stimulant in tobacco, has many well-documented behavioral effects, which often diminish (i.e. tolerance develops) when it is given daily. Male Long Evans rats initially were trained to respond under a multiple variable-ratio 30-response variable-interval 60-s (mult VR-30 VI 60-s) schedule of food reinforcement. They were then divided into 12 groups of 8 that received four weekly subcutaneous injections of anatoxin-a (0.05-0.2 mg/kg), nicotine (0.125-1.8 mg/kg), or vehicle 5-min prior to testing. When initially administered, each compound decreased response rates and reinforcement rates in both components of the multiple schedule. Substantial tolerance developed to the disruptive effects of nicotine with weekly administration. Tolerance also developed to the effects of anatoxin-a, although to a lesser degree; the highest dose severely decreased performance with little evidence of recovery. In conjunction with prior findings, these results suggest the behavioral effects of anatoxin-a and nicotine are similar, but not identical, and that relatively infrequent (episodic) administration can produce tolerance.

MDMA and learning: effects of acute and neurotoxic exposure in the rat.

In two experiments, the effects of MDMA on the acquisition of lever-press responding of rats were examined under procedures in which water delivery was delayed by 0, 10, or 20 s relative to the response that produced it. In the first study, experimentally naive, water-deprived rats received an intraperitoneal injection of MDMA (0, 1.0, 3.2, or 5.6 mg/kg) prior to one 8-h experimental session. Response acquisition was observed under all conditions at all drug doses. MDMA increased the total number of responses emitted and the total number of water deliveries earned in dose-dependent fashion, but only when reinforcement was immediate. Under conditions of delay, MDMA had no effect on either measure. Under all reinforcement conditions, higher doses of MDMA typically produced an initial reduction in lever pressing, and in that sense interfered with learning. In the second study, rats received an MDMA injection regimen previously shown to be neurotoxic. Control rats received saline solution according to the same injection schedule. Two weeks after completing the regimen, rats were water deprived and exposed to behavioral procedures as described for the first experiment. Although MDMA significantly reduced 5-HT and 5-HIAA levels in the striatum and prefrontal cortex, mean performance of rats exposed to MDMA did not differ from that of rats exposed to vehicle. Twenty-five percent of the rats exposed to MDMA and delayed reinforcement did fail to acquire responding, which suggests that further study of the effects of neurotoxic doses of MDMA on initial response acquisition is warranted.

Effects of cocaine and morphine under mixed-ratio schedules of food delivery: support for a behavioral momentum analysis.

Previous studies have shown that ratio size influenced the development of tolerance under simple and multiple schedules, but not under progressive-ratio (PR) schedules. PR schedules share certain features with mixed-ratio (MR) schedules, and pilot data suggested that ratio size fails to modulate tolerance to cocaine or morphine under MR schedules. The present study examined more comprehensively the pre- and postchronic effects of cocaine and (in separate birds) morphine under MR schedules with fixed-ratio (FR) 5 and FR 95, FR 25 and FR 75, and FR 50 and FR 50 components. Acute doses of cocaine and morphine initially were given in an ascending series (beginning with 0.56 mg/kg) until responding was reduced to near-zero levels. Chronic (daily) dosing with a dose that reduced, but did not eliminate, responding then occurred until response rates stabilized. Finally, postchronic dose-response determinations were conducted. Both cocaine and morphine reduced response rates at all FR values. Tolerance was consistently observed to the effects of morphine, but not to those of cocaine. With both drugs the degree of tolerance observed did not vary as a function of FR value. These findings, like those obtained under PR schedules, indicate that ratio size does not always modulate drug tolerance. A behavioral momentum analysis of drug action appears to account for whether or not ratio size modulates tolerance, and such an analysis is provided.

Publication trends in The Analysis of Verbal Behavior: 1982-1998.

Every article published in The Analysis of Verbal Behavior (TAVB) from its inception as a newsletter through 1998 was rated along several dimensions. Results indicated that the journal has grown substantially over time. Most articles (overall, 73%) published in TAVB did not describe experiments. The experiments that were described characteristically used within-subject designs and direct measures of behavior. They were conducted mostly by researchers in academic settings, using students as participants. Several authors have recently suggested that the journal should publish more experimental articles, covering a wider range of topics. The present results show that there is indeed room for more experimental articles, although they also underscore that the Journal has played, and continues to play, a major role as an outlet for both empirical and theoretical analyses of verbal behavior.

Direct service staff and their perceptions of psychotropic medication in non-institutional settings for people with intellectual disability.

Previous studies have surveyed a variety of service providers in school and institutional settings, and reported a pervasive lack of education and training with regard to the use of psychotropic medication in people with intellectual disability. Because an increasing number of people with intellectual disability are living in the community and since many of these people receive psychotropic medications, the present study extended research in this area by surveying direct service staff to determine their perceptions, knowledge and opinions with regard to the use of psychotropic medication in non-institutional settings for individuals with developmental disabilities. Consistent with the findings of previous studies, a majority of the 334 respondents in the present study reported that they had not received adequate training in the area of drug treatment The knowledge and skills deficits of direct service staff appear to represent a significant barrier to the appropriate monitoring and management of pharmacotherapy for individuals with intellectual disability. Therefore, a systematic training programme to educate direct service staff about psychotropic medication needs to be designed, implemented and disseminated on a broad scale.

Acute and chronic effects of morphine under a progressive-ratio 25 schedule of food delivery.

The present study examined the effects of morphine in pigeons responding under a progressive-ratio 25 schedule of food delivery. Morphine initially reduced response rates and breaking points. With chronic exposure, tolerance developed to these effects. The magnitude of the observed tolerance was not obviously different from that previously reported under a PR 5 schedule of food delivery. In addition, when drug effects were compared under the fixed-ratio 25 and fixed-ratio 100 components comprised by the progressive-ratio schedule, comparable tolerance was observed. Although prior studies using other procedures have shown that ratio size modulates the development of tolerance to morphine and other drugs, the present data suggest that this relation is constrained, and is not easily observed under progressive-ratio schedules.

Establishing morphine and U-50,488H as discriminative stimuli in a three-choice assay with pigeons.

Pigeons were trained in a 3-choice assay to discriminate among injections of 5.6 mg/kg U-50,488H, 5.6 mg/kg morphine, and vehicle solution. In dose-response tests, subjects rarely responded on the U-50,488H-appropriate key when morphine was administered or on the morphine-appropriate key when they received U-50,488H. A high dose of naltrexone (1.0 mg/kg) completely blocked the morphine cue but failed to block completely the U-50,488H cue. In generalization tests, d-amphetamine primarily engendered saline-appropriate responding. Ethylketazocine produced mixed results, in that moderate doses produced responding on both the morphine- and U-50,488H-appropriate keys, but 3.2 mg/kg engendered primarily morphine-appropriate responding. These results demonstrate the feasibility, but not necessarily the value, of 3-choice discrimination procedures involving mu and kappa agonists and vehicle.

Response acquisition with delayed reinforcement: a comparison of two-lever procedures.

Groups of 8 experimentally naive rats were exposed during 8-hr sessions to resetting delay procedures in which responses on one lever (the reinforcement lever) produced water after a delay of 8, 16, 32, or 64 s. For rats in one condition, responses on a second (no-consequences) lever had no programmed consequences. For rats in another condition, responses on a second (cancellation) lever during a delay initiated by a response on the reinforcement lever prevented delivery of the scheduled reinforcer; responses on the cancellation lever at other times had no programmed consequences. Under both conditions and at all delays, most subjects emitted more responses on the reinforcement lever than did control rats that never received water emitted on either lever. At 8-s delays, both conditions engendered substantially more responding on the reinforcement lever than on the other lever, and performance closely resembled that of immediate-reinforcement controls. At delays of 16 and 32 s, however, there was clear differential responding on the two levers under the cancellation condition but not under the other condition. When the delay was 64 s, differential responding on the two levers did not occur consistently under either condition. These findings provide strong evidence that the behavior of rats is sensitive to consequences delayed by 8, 16, and 32 s, but only equivocal evidence of such sensitivity to consequences delayed 64 s. They also indicate that acquisition depends, in part, on the measure of performance used to index it.

Acquisition, extinction, and reacquisition of responding with delayed and immediate reinforcement.

The present study investigated acquisition, extinction, and reacquisition of free-operant responding when rats' lever presses produced water after a resetting delay of 0, 10, 20, or 30 s. Results indicated that: (1) responding was acquired rapidly at all delays without shaping or autoshaping; (2) resistance to extinction was directly related to delay length and inversely related to intermittency of reinforcement; (3) responding acquired with delayed reinforcement recovered less rapidly from extinction, and was less efficient, than responding acquired with immediate reinforcement. Comparing these results with those of studies using discrete-trials and free-operant procedures with no reinforcement delay suggest that the specific conditions under which behavior is maintained determines, in part, the behavioral effects of delay and intermittency of reinforcement.

Drug abuse in persons with mental retardation: a review.

The literature on drug abuse by people with mental retardation, a real, but largely ignored problem, was reviewed. Topics addressed were (a) the prevalence of drug use, (b) the drug-related problems characteristically encountered by this population, (c) the special vulnerabilities of people with mental retardation, (d) the treatment programs used with (and appropriate for) people with mental retardation, and (e) the status of drug abuse prevention and drug education for this population. Controlled research dealing with the genesis, treatment, and prevention of drug abuse among people with mental retardation is essentially nonexistent, but badly needed.

Effects of chlorpromazine on rats' acquisition of lever-press responding with immediate and delayed reinforcement.

The effects of chlorpromazine (0, 2, 6, and 10 mg/kg) on the acquisition of lever-press responding by rats were examined under conditions where reinforcement (water delivery) was immediate or delayed. Under the immediate reinforcement condition, water-deprived rats were exposed during 8-h sessions to a fixed-ratio 1 (FR 1) schedule of water delivery without prior autoshaping or hand shaping. Under the delayed reinforcement condition, similar rats were exposed to a tandem FR 1 fixed-time 8-s schedule of water delivery. A different squad of eight rats was exposed to each delay condition and drug dose. For all subjects, responses on one lever produced water and responses on a second lever had no programmed consequences. Regardless of whether reinforcement was immediate or delayed, chlorpromazine reduced in dose-dependent fashion the mean number of operative-lever responses emitted, which suggests that the drug interfered with learning. At all chlorpromazine doses except 10 mg/kg, substantially more operative-lever than inoperative-lever responding occurred, indicating that the operant response was acquired. Chlorpromazine at 2 and 6 mg/kg disrupted the acquisition of stimulus control by the operative lever when reinforcement was delayed, but not when it was immediate. At 10 mg/kg, most subjects did not acquire lever-pressing regardless of whether they were exposed to the immediate or delayed reinforcement procedure. Procedures similar to those used in the present study appear to provide a reasonable assay for examining how drugs affect the initial behavioral effects of immediate and delayed reinforcement, and may merit further investigation.

Reporting of medication regimen in applied studies of persons with mental retardation and ADHD.

The present survey determined whether articles describing attempts to alter behavior in people with mental retardation and Attention-Deficit/Hyperactivity Disorder (ADHD) (a) reported whether or not participants were receiving medications, (b) evaluated drugs as independent variables, and (c) evaluated (or discussed) interactions between pharmacological and nonpharmacological treatments. All behavior-change articles published from 1991 through 1995 in 10 major journals were evaluated. In contrast to the results of earlier surveys, nearly 40% of studies involving participants with mental retardation provided information about medication. This change appears to represent a significant methodological improvement. Nearly 60% of articles involving persons with ADHD provided information about medication. Studies of drugs were common when participants were people with ADHD, but not when they were people with mental retardation. The psychopharmacology of mental retardation continues to be a small, but important, research area. Studies examining treatment interactions were rare, regardless of participants' characteristics. Given that pharmacological treatments may alter participants' sensitivity to nonpharmacological interventions, further research in this area is sorely needed.

MDMA and d-amphetamine produce comparable effects in pigeons performing under a multiple fixed-ratio interresponse-time-greater-than-t schedule of food delivery.

The purpose of this study was to gain further information about the behavioral effects of (+/-) 3.4-methylenedioxymethamphetamine (MDMA) on schedule-controlled responding. MDMA (0.32, 0.56, 1.0, 3.2, 5.6, and 10 mg/kg) and d-amphetamine (0.32, 0.56, 1.0, 3.2, 5.6, and 10 mg/kg) were administered to pigeons performing under a multiple fixed-ratio 30 (FR 30) interresponse-time-greater-than-15-s (IRT > 15-s) schedule of food delivery. In general, both drugs had no significant effect on response rates under the IRT > 15-s component at doses that decreased rates under the FR component. Results of the present experiment indicate that under some conditions MDMA and d-amphetamine produce similar, and rate-dependent, effects.

Using self-management procedures to improve the productivity of adults with developmental disabilities in a competitive employment setting.

This study describes the use of self-management procedures, similar to those proposed by Lagomarcino, Hughes, and Rusch (1989), to improve the productivity of 2 women with mild mental retardation who worked in restaurants. Substantial improvements were observed as a function of treatment, and the procedures were deemed acceptable by the participants, their coworkers, and their supervisors.

Behavior analysis and farm animal welfare.

This article demonstrates that there is a role for behavior-analytic techniques in the area of farm animal welfare and provides examples of the kinds of work that can be done. Behavior-analytic procedures, specifically those used in the study of psychophysics, preference, and demand, can provide answers to three questions people concerned with the welfare of farm animals are likely to ask: What can the animals detect? What do they like and dislike? What will they work to attain or preserve? Such information certainly is necessary for making reasonable decisions about animal welfare, although it is not sufficient in and of itself.

Concurrent schedule performance in domestic goats: persistent undermatching.

Performance of nine domestic goats responding under concurrent variable-interval variable-interval schedules of food delivery was examined, with results analyzed in terms of the generalized matching equation. Substantial undermatching of response and time allocation ratios to obtained reinforcement ratios was evident. Post-reinforcement pause time ratios approximately matched obtained reinforcement ratios. Subtracting these times from total time allocation values yielded net time allocation ratios, which undermatched obtained reinforcement ratios to a greater degree than whole-session time allocation ratios. Slopes of regression lines relating behavioral outputs to environmental inputs characteristically were below 0.6, which is similar to previous findings in dairy cows tested under comparable conditions.

Demand curves for food in hens: Similarity under fixed-ratio and progressive-ratio schedules.

Demand curves were generated for five domestic hens under progressive-ratio 5 schedules of food delivery and under fixed-ratio schedules of food delivery that began at fixed-ratio 5 and were incremented by 5 each session. All sessions ended after 10 consecutive minutes without a response. Although response rates at a given ratio were higher under the progressive-ratio schedule, all hens completed higher ratios under the fixed-ratio schedule. Similar, but not identical, demand curves were generated under progressive-ratio and fixed-ratio schedules. Under both schedules, consumption (reinforcers earned) decreased as cost (ratio size) increased. Data generally were well described by an equation in which elasticity of demand is constant, although an equation in which elasticity could vary accounted for slightly more of the variance.

Effects of D-amphetamine on response acquisition with immediate and delayed reinforcement.

The present study examined in 8-hour sessions the effects of d-amphetamine (1.0, 5.6, and 10 mg/kg) on the acquisition of lever-press responding in rats that were exposed to procedures in which water delivery was delayed by 0, 8, or 16 seconds relative to the response that produced it. Both nonresetting- and resetting-delay conditions were studied. Although neither shaping nor autoshaping occurred, substantial levels of operative-lever responding developed under all conditions in which responses produced water. The lowest dose (1.0 mg/kg) of d-amphetamine either had no effect on or increased operative-lever pressing, whereas higher doses typically produced an initial reduction in lever pressing. Nonetheless, overall rates of operative-lever pressing at these doses were as high as, or higher than, those observed with vehicle. Thus, response acquisition was observed under all reinforcement procedures at all drug doses. In the absence of the drug, most responding occurred on the operative lever when reinforcement was immediate. Such differential responding also developed under both nonresetting- and resetting-delay procedures when the delay was 8 seconds, but not when it was 16 seconds. d-Amphetamine did not affect the development of differential responding under any procedure. Thus, consistent with d-amphetamine's effects under repeated acquisition procedures, the drug had no detrimental effect on learning until doses that produced general behavioral disruption were administered.

Failure to induce defecation in rats exposed to fixed-time schedules of liquid food delivery.

Previous studies have found that defecation increases in rats exposed to fixed-time schedules of dry food delivery. The purpose of the present study was to examine whether increases in defecation could be induced in rats exposed to fixed-time schedules of liquid food delivery. Eight rats were exposed to fixed-time 30-, 60-, and 120-s schedules of liquid food delivery. None of the subjects excreted significantly more fecal boli under the fixed-time schedules than during massed-food control sessions in which an equivalent amount of food was presented at the beginning of the sessions. Thus, the present findings identify a previously unknown constraint on schedule-induced defecation in rats.

Acute and chronic effects of morphine in pigeons responding under a progressive-ratio schedule of food delivery.

Although progressive-ratio schedules have often been used by behavioral pharmacologists to index the relative reinforcing effects of drugs of abuse, they have been ignored in the study of tolerance to opioids. The present study examined tolerance to morphine in pigeons responding under a progressive-ratio 5 schedule of food delivery. Acute administrations of morphine produced general dose-dependent reductions in response rates and breaking points. Dose-response curves for both measures shifted rightward substantially (roughly fivefold) following chronic (daily) exposure to morphine, indicating that tolerance developed to the drug's effects.