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PubMed1975

The impact of two different reinforcers on conditioned operant heart-rate acceleration and deceleration.

The effects of two types of reinforcers on operant heart-rate acceleration and deceleration conditioning were examined over a number of sessions. The initial use of monetary reinforcement facilitated discriminative pre-trial to trial heart-rate acceleration during sessions utilizing both monetary reinforcement and visual feedback. The initial use of visual feedback did not produce such discriminative control, but the subsequent use of monetary reinforcement resulted in increases in pre-trial and trial heart rate over sessions. No effects due to type of reinforcement were noted for heart-rate deceleration. Increases and decreases in cardiovascular functioning were imposed upon a background of increased skin responding. The cardiovascular responses that developed over sessions appeared to be relatively independent of changes in skin response.

Conditioning, Operant↗
PubMed1985

Context of drinking and reinforcement from alcohol: alcoholic patterns.

Alcohol is perceived as producing a variety of kinds of reinforcement. The present study examined whether alcohol reinforcement varied with the usual social and physical context of drinking for 268 male and female adult alcoholics. Results indicate that alcoholics anticipate different types of reinforcement from alcohol depending on their usual companions when drinking. In general, those drinking in more impersonal social contexts expect a greater reinforcing impact from drinking than peers who drink in more intimate contexts. Alcohol reinforcement expectancies of men were not found to differ in terms of the usual physical context of drinking.

Adult↗
PubMed1994

Evaluation of the reinforcing effects of eliprodil in rhesus monkeys and its discriminative stimulus effects in rats.

Two studies examined the abuse potential of the N-methyl-D-aspartate (NMDA) non-competitive antagonist eliprodil [(+/-)-alpha-(4-chlorophenyl)-4-[(fluorophenyl)methyl]-1- piperidineethanol] by evaluating its reinforcing effects in rhesus monkeys and its phencyclidine (PCP)-like discriminative stimulus effects in rats. The monkeys were trained to self-administer PCP i.v. under a fixed ratio 10 schedule of reinforcement. After the monkeys were trained, saline, vehicle and various doses of eliprodil were substituted for PCP. The rats were trained to discriminate 3 micrograms/kg PCP from saline using a standard two-lever discrimination procedure with correct-lever responding reinforced under a fixed ratio 10 schedule of food reinforcement. After acquiring the discrimination, the rats were tested with various doses of PCP, dizocilpine and eliprodil. The self-administration study showed that eliprodil did not have reinforcing effects, since it maintained injection rates comparable to the negative controls, saline and vehicle. In the discrimination study it was found that the higher doses of PCP and dizocilpine resulted in 100% PCP-associated lever responding, whereas eliprodil occasioned no responding on the PCP-associated lever. The results from these studies suggest that eliprodil has a low potential for abuse in humans as well as providing further evidence that eliprodil produces a profile of behavioral effects unlike the PCP-site selective NMDA antagonists.

Animals↗
PubMed1994

Contingent methadone take-home doses reinforce adjunct therapy attendance of methadone maintenance patients.

Two studies utilized within-subjects designs to determine whether take-home methadone doses can reinforce adjunct therapy attendance of drug abuse patients. These studies varied the reinforcement density and the schedule of methadone take-home doses. In Study 1, patients (n = 10) either could or could not receive a take-home following each therapy session. Study 2 patients (n = 15) could either earn take-homes following each therapy session attended (i.e., 2 take-homes per week) or could earn one take-home dose following each attendance to two consecutive sessions attended. In both studies experimental conditions alternated during three-week blocks of time. Across studies, any reinforcement by take-home doses produced more attendance at therapy sessions than that observed in the no reinforcement condition. Take-home incentive effects were strongest when each of the two weekly therapy sessions was reinforced by a methadone take-home dose. Increased attendance was not associated with reduced drug use, due perhaps to high rates of pre-study drug use and limited therapy duration. Contemporary opioid abusers present with multiple problems that methadone was never intended to treat. The present studies illustrate a method by which methadone treatment can improve the likelihood of delivering other services that may prove effective in treating some of these problems.

Adult↗
PubMedDate not supplied

Specific decreases in ethanol- but not water-reinforced responding produced by the 5-HT3 antagonist ICS 205-930.

The serotonin 5-HT3 antagonist ICS 205-930 has been shown to block the discriminative stimulus properties of ethanol and decrease voluntary intake, suggesting a possible role for 5-HT3 systems in the reinforcing effects of ethanol. ICS 205-930 (0.56, 1.0, 3.0, 10.0, and 17.0 mg/kg i.p.) was examined on ethanol and water self-administration in an operant paradigm. Following a sucrose-fading procedure, two groups of nondeprived rats responded on either a concurrent fixed ratio 4 schedule for ethanol (10% v/v) and water (CONC FR4 FR4), or a single FR4 schedule for ethanol (10% v/v). ICS 205-930 dose-dependently decreased ethanol-reinforced responding in the concurrent condition without decreasing water-reinforced responding, suggesting a specific effect on ethanol. Ethanol-reinforced responding was also dose-dependently decreased in the single FR4 condition, but the dose effect curve was shifted to the left. These data support the conclusions that 5-HT3 systems may play a specific role in ethanol self-administration that is independent of general appetitive and motor processes, and that 5-HT3 antagonists may have therapeutic efficacy in the treatment of alcohol abuse when multiple reinforcers are available.

Alcohol Drinking↗
PubMedDate not supplied

Regulation of operant ethanol-reinforced behavior is genetically independent of regulation of withdrawal severity in WSP and WSR mice.

Selectively bred withdrawal seizure prone (WSP1 and WSP2) and withdrawal seizure resistant (WSR1 and WSR2) mice were used to test the extent to which severity of ethanol withdrawal response is predictive of the reinforcing effects of ethanol. Mice were systematically introduced to ethanol under a fixed ratio 1 (FR 1) schedule using adjunctive drinking methods. There were no significant differences in ethanol consumption between the lines during training. Subsequently, responding for ethanol concentrations of 8%, 0% (vehicle control), and 8% retest under a FR 1 schedule in the absence of food induction was measured. Group data showed that ethanol did not serve as a reinforcer in the test phase within any of the four lines, and there were no significant line differences in rate of responding, intake, or blood ethanol concentrations (BEC). Mice were next tested for responding for ethanol under a FR 4 schedule. Again, ethanol did not serve as a reinforcer for any of the four groups, and there were no significant differences between the lines. However, further analysis showed that there were individual differences in responding within each group, some animals were apparently reinforced by ethanol, while others showed no reinforcement and some appeared to avoid ethanol. There was no systematic pattern within or between groups for these individual differences in responding. Thus, both the group results as well as the behavior patterns of individual animals are consistent with the conclusion that genes regulating rewarding effects of ethanol appear to be segregating randomly across groups and are independent of genes mediating ethanol withdrawal severity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Current limits to reinforcer identification for some persons with profound multiple disabilities.

Fifteen persons with profound mental retardation were divided into two groups. One group was identified with chronic training needs by habilitative staff and the other group served as a control. In an attempt to identify a reinforcer, each participant received a preference assessment and a simple, low-effort treatment procedure. In Experiment 1, only individuals who approached at least one stimulus on 80% or more of the preference assessment trials ("high preference") showed reinforcement effects in treatment. However, three individuals showing high preference failed to show treatment effects. All persons identified with chronic training needs failed to show reinforcement effects. Experiment 2 analyzed characteristics of the two groups and found significant differences in overall movement and response latency. Limitations of the current reinforcement technology were apparent for identifying reinforcers in the group with chronic training problems. Research is suggested for evaluating training alternatives for people with profound multiple disabilities who move very little or who respond with very long latencies.

Adult↗
PubMed2006

The reinforcing, subject-rated, performance, and cardiovascular effects of d-amphetamine: influence of sensation-seeking status.

Individual differences that may contribute to vulnerability to abuse drugs have been identified. Sensation-seeking status has been shown to influence both vulnerability to drug use and response to acute drug administration. The purpose of the present experiment was to examine the reinforcing effects of d-amphetamine in high and low sensation-seeking subjects using a modified progressive-ratio procedure. A battery of subject-rated, performance, and cardiovascular measures was also included to better characterize the effects of d-amphetamine in these groups. Ten high sensation seekers and ten low sensation seekers that were matched for education, age, drug use, height, and weight, first sampled doses of d-amphetamine (0, 8, and 16 mg). In subsequent sessions, subjects were offered the opportunity to work for the sampled dose on a modified progressive-ratio procedure. d-Amphetamine functioned as a reinforcer and produced prototypical stimulant-like effects (e.g., increased subject-ratings of Like Drug, enhanced performance, and increased heart rate). High sensation seekers were more sensitive than low sensation seekers to the reinforcing and some of the subject-rated effects of d-amphetamine. The results of the present experiment extend those of previous findings by demonstrating that the reinforcing effects of d-amphetamine vary as a function of the biologically based sensation-seeking personality trait. These results suggest that increased stimulant drug use and abuse among high sensation seekers may be related, in part, to increased sensitivity to the reinforcing effects of stimulants among these individuals.

Adult↗
PubMed2006

Response acquisition with delayed reinforcement in a rodent model of attention-deficit/hyperactivity disorder (ADHD).

The spontaneously hypertensive rat (SHR) has been shown to exhibit behavioral characteristics analogous to those exhibited by humans diagnosed with attention-deficit/hyperactivity disorder (ADHD). The present study was conducted to further evaluate the validity of the SHR model of ADHD by characterizing learning of a novel response under conditions of delayed reinforcement. Seven experimentally naïve SHRs and a control group of seven normotensive Wistar-Kyoto (WKY) rats were exposed to a contingency where one lever press initiated pellet delivery after a 15-s, resetting delay. Rats in both groups acquired lever pressing, and the pattern of acquisition was well described with a three-parameter, sigmoidal equation. Response acquisition was retarded in the SHRs; they took longer to acquire the behavior, exhibited lower response rates and earned fewer reinforcers over the course of the experiment. When reinforcer delivery was made immediate in a subsequent condition, the SHRs exhibited higher response rates than the WKY, suggesting that the lower rates of responding seen in the SHRs were due to the reinforcer delay. The results replicate previous research on response acquisition with delayed reinforcement and provide further validation of the SHR strain as a model of ADHD. Like humans diagnosed with ADHD, the SHRs appear to be hypersensitive to delayed consequences, which in the present context, interfered with learning a novel behavior.

Animals↗
PubMed2005

The role of common reinforced comparison responses in acquired sample equivalence.

Different samples occasioning the same reinforced comparison response in matching-to-sample are interchangeable for one another outside of original training. The present studies were designed to verify the role of these common responses in producing acquired sample equivalence by explicitly varying the presence or absence of this commonality during training. In each of the two experiments, one group of pigeons made the same reinforced choice response following multiple sample stimuli, whereas controls either made different reinforced choices following each sample (Experiment 1) or reinforced choices after only two of four center-key stimuli (Experiment 2). Later, two of the original samples/center-key stimuli were established as conditional cues for new comparison responses, after which the ability of the remaining samples/center-key stimuli to occasion those new responses was assessed. Following common-response training, matching accuracy was higher on class-consistent than on class-inconsistent transfer tests, whereas accuracy in the controls was generally intermediate between these two extremes, a pattern similar to that reported in the human paired-associate literature. These findings confirm that occasioning the same reinforced choice response is one means by which disparate samples become functionally equivalent.

Animals↗
PubMed2005

Stimulus change dis-habituates operant responding supported by water reinforcers.

The present experiment examined whether habituation contributes to within-session decreases in operant responding for water reinforcers. The experiment asked if this responding can be dis-habituated, a fundamental property of habituated behavior. During baseline, rats' lever pressing was reinforced by water on a variable interval 15-s schedule. During experimental conditions, rats responded on the same schedule and a new stimulus was introduced for 5 min at 15, 30 or 45 min into the 60-min session. The new stimulus was extinction, continuous reinforcement or flashing lights in different conditions. Rate of responding primarily decreased within the session during baseline. Introducing a new stimulus sometimes suppressed (extinction, continuous reinforcement) and sometimes increased (flashing lights) responding while it was in effect. The new stimulus increased responding after it ended and before it was presented in the session. The results are incompatible with the idea that non-habituation satiety factors (e.g., cellular hydration and blood volume) contributed to within-session changes in responding. These satiety factors should increase with increases in consumption, decrease with decreases in consumption and remain constant with constant consumption of water. Nevertheless, all stimulus changes increased operant responding for water. These results support the idea that habituation contributes to within-session decreases in responding for water reinforcers.

Animals↗
PubMed2004

Reinforcement-related neurons in the primate basal forebrain respond to the learned significance of task events rather than to the hedonic attributes of reward.

The objective of this study was to determine if the responses of basal forebrain neurons are related to the cognitive processes necessary for the performance of behavioural tasks, or to the hedonic attributes of the reinforcers delivered to the monkey as a consequence of task performance. In all cases, it was found that the primary neuronal responses were to visual stimuli that required analysis important for the selection of a behavioural response and not to the delivery of reinforcement per se. Indeed, reinforcement-related neurons that responded only to the delivery of juice or of saline were never encountered. In additional experiments, it was found that abstract visual cues-specific gestures of the experimenter-that signaled the impending delivery of reinforcement were able to activate these neurons. These data are consistent with the view that reinforcement-related basal forebrain neurons influence the sensory and motor processes in the cerebral cortex, providing control signals that optimise the processing of complex sensory stimuli and/or the generation of appropriate behavioural responses.

Animals↗
PubMed2004

The impact of reinforcement contingencies on AD/HD: a review and theoretical appraisal.

One of the core deficits in attention deficit/hyperactivity disorder (AD/HD) is thought to be an aberrant sensitivity to reinforcement, such as reward and response cost. Twenty-two studies (N=1181 children) employing AD/HD and reinforcement contingencies are reviewed from vantage points: task performance, motivation, and psychophysiology. Results indicate that reinforcement contingencies have a positive impact on task performance and levels of motivation for both children with AD/HD and normal controls. There is evidence that the effect related to task performance is somewhat more prominent in AD/HD. There is some evidence that a high intensity of reinforcement is highly effective in AD/HD. Children with AD/HD prefer immediate over delayed reward. From a psychophysiological point of view, children with AD/HD seem less sensitive to reinforcement compared to controls. While comorbid disorders are suggested to be confounders of the dependent variables, many studies do not examine the effect of oppositional defiant disorder (ODD) and conduct disorder (CD). We discuss the implications of the findings for five theoretical frameworks, including the model by, the cognitive-energetic model (CEM), the dual-pathway model and the BIS/BAS model. Results show a discrepancy between the theoretical models and the behavioural findings.

Antisocial Personality Disorder↗
PubMed2004

A comparison of the reinforcing efficacy of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") with cocaine in rhesus monkeys.

The purpose of the present study was to compare the reinforcing efficacy of 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') to cocaine. Rhesus monkeys (n=4) responded under a within-session, exponentially increasing, progressive-ratio (PR) schedule of cocaine reinforcement. Breaking point (BP) for the PR schedule was defined as the final response requirement completed before 2 h had elapsed without an injection delivered. Saline and doses of cocaine (0.003-0.3 mg/kg/injection) and MDMA (0.01-0.56 mg/kg/injection) were substituted for the training dose of cocaine for at least five consecutive sessions. Both cocaine and MDMA functioned as reinforcers, but self-administration of MDMA occurred at fewer doses and a significantly lower peak BP was obtained for MDMA. These data demonstrate that MDMA functions as a reinforcer, although its reinforcing efficacy appears to be less than that of cocaine.

Amphetamines↗
PubMed2003

Stimulant and reinforcing effects of cocaine in monoamine transporter knockout mice.

A large body of evidence supports the hypothesis that the reinforcing effects of cocaine depend on its ability to block the dopamine transporter (DAT), thereby increasing dopamine extracellular concentration within the mesocorticolimbic system. However, the fact that cocaine similarly binds to the serotonin and norepinephrine transporters (SERT and NET, respectively), raises the possibility that modulation of mesocorticolimbic dopaminergic transmission might be achieved through alternate pathways. The successful disruption of the genes coding for the DAT, the SERT and the NET offered ideal tools to determine the extent of the participation of these transporters and respective monoaminergic systems in the reinforcing effects of cocaine. Studies of cocaine-induced motor activation and maintenance of intravenous (i.v.) self-administration in DAT- and in NET-knockout (KO) mice are reviewed here, and discussed in light of new observations obtained from double monoamine transporters KO mice (i.e., DAT-KO/SERT-KO, NET-KO/SERT-KO). The reinforcing potency of cocaine is maintained in the absence of the DAT but decreased in the absence of the NET; its motivational rewarding effect is observed in the absence of the SERT, but not when both DAT and SERT are lacking. Moreover, a dichotomy between cocaine motor activating and reinforcing effects is reported. Such dichotomy is suggestive of independent mechanisms underlying the psychomotor stimulant and reinforcing effects of cocaine. Overall, these studies provide evidence that cocaine dynamically acts at multiple sites through pathways that might be exchangeable under certain circumstances.

Animals↗
PubMed2004

Ultraviolet exposure is a reinforcing stimulus in frequent indoor tanners.

BACKGROUND: Investigations into tanners' reasons for tanning have focused primarily on the perception of improved appearance. Reported relaxing effects of tanning suggest the possibility of a physiologic effect of UV that drives tanning behavior. OBJECTIVE: We sought to determine if there is a physiologic reinforcing effect of UV exposure, separate from appearance motivation, that may contribute to tanning behavior. METHODS: We determined the reinforcing effect of UV light in a series of controlled, blinded, repeated-choice trials of UV carefully designed to separate as cleanly as possible reinforcing effects of UV exposure from other factors including perceived benefits of having a tan. A total of 14 young adults who used tanning beds regularly were exposed to otherwise identical UV and non-UV tanning bed stimuli on Mondays and Wednesdays for 6 weeks. On Fridays, participants had concurrent access to the two beds. The primary dependent variable was the percentage of choice sessions during which more UV than non-UV tanning was chosen. RESULTS: In all, 12 participants chose additional tanning exposure on Fridays and, of these, 11 consistently used the UV bed for that exposure. Of the total 41 occasions when participants chose to tan on Friday, 39 sessions (95%) were for the UV bed and only two for the non-UV bed. A more relaxed and less tense mood was reported after UV exposure compared with after non-UV exposure (P=.008 and P=.002, respectively). DISCUSSION: When exposed to UV and non-UV under blinded conditions, frequent tanners can distinguish the two conditions and undertake further UV exposure, indicating that UV is a reinforcing stimulus. The relaxing and reinforcing effects of UV exposure contribute to tanning behavior in frequent tanners and should be explored in greater detail.

Adult↗
PubMed2005

The mesolimbic dopamine system: the final common pathway for the reinforcing effect of drugs of abuse?

In this review we will critically assess the hypothesis that the reinforcing effect of virtually all drugs of abuse is primarily dependent on activation of the mesolimbic dopamine system. The focus is on five classes of abused drugs: psychostimulants, opiates, ethanol, cannabinoids and nicotine. For each of these drug classes, the pharmacological and physiological mechanisms underlying the direct or indirect influence on mesolimbic dopamine transmission will be reviewed. Next, we evaluate behavioral pharmacological experiments that specifically assess the influence of activation of the mesolimbic dopamine system on drug reinforcement, with particular emphasis on animal experiments using drug self-administration paradigms. There is overwhelming evidence that all five classes of abused drugs increase dopamine transmission in limbic regions of the brain through interactions with a variety of transporters, ionotropic receptors and metabotropic receptors. Behavioral pharmacological experiments indicate that increased dopamine transmission is clearly both necessary and sufficient to promote psychostimulant reinforcement. For the other four classes of abused substances, self-administration experiments suggest that although increasing mesolimbic dopamine transmission plays an important role in the reinforcing effects of opiates, ethanol, cannabinoids and nicotine, there are also dopamine-independent processes that contribute significantly to the reinforcing effects of these compounds.

Animals↗
PubMed2005

Increased gabaergic input to ventral tegmental area dopaminergic neurons associated with decreased cocaine reinforcement in mu-opioid receptor knockout mice.

There is general agreement that dopaminergic neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens and prefrontal cortex play a key role in drug reinforcement. The activity of these neurons is strongly modulated by the inhibitory and excitatory input they receive. Activation of mu-opioid receptors, located on GABAergic neurons in the VTA, causes hyperpolarization of these GABAergic neurons, thereby causing a disinhibition of VTA dopaminergic neurons. This effect of mu-opioid receptors upon GABA neurotransmission is a likely mechanism for mu-opioid receptor modulation of drug reinforcement. We studied mu-opioid receptor signaling in relation to cocaine reinforcement in wild-type and mu-opioid receptor knockout mice using a cocaine self-administration paradigm and in vitro electrophysiology. Cocaine self-administration was reduced in mu-opioid receptor knockout mice, suggesting a critical role of mu-opioid receptors in cocaine reinforcement. The frequency of spontaneous inhibitory post-synaptic currents onto dopaminergic neurons in the ventral tegmental area was increased in mu-opioid receptor knockout mice compared with wild-type controls, while the frequency of spontaneous excitatory post-synaptic currents was unaltered. The reduced cocaine self-administration and increased GABAergic input to VTA dopaminergic neurons in mu-opioid receptor knockout mice supports the notion that suppression of GABAergic input onto dopaminergic neurons in the VTA contributes to mu-opioid receptor modulation of cocaine reinforcement.

Afferent Pathways↗