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At least 397 records · Page 22Linked to original sources
PubMed1998

Prefrontal cortex infusions of SCH 23390 cause immediate and delayed effects on ventral tegmental area stimulation reward.

A reward-relevant relationship between dopamine projection regions of the ventral tegmental area (VTA) was investigated through the use of brain stimulation reward (BSR) thresholds. Using a rate-free method, changes in VTA BSR thresholds were determined after intracranial injections of the dopamine D1 antagonist, SCH 23390 into the prefrontal cortex (PFC), or the nucleus accumbens (NAcc). Reward thresholds assessed immediately after the infusion of SCH 23390 into the NAcc (0.5 microgram/0.5 microliter/side) were significantly higher than those assessed just after saline infusions, indicating a drug-induced attenuation of the rewarding effects of the brain stimulation. The effects of this dose subsided when tested 24 h later. Conversely, intra-PFC infusions of SCH 23390 at the same dose (0.5 microgram/0.5 microliter/side) resulted in lowered BSR thresholds when rats were tested immediately after infusion. In addition, animals tested 24 h after receiving the lowest dose (0.125 microgram/0.5 microliter/side) demonstrated a robust delayed threshold-lowering effect. These immediate and delayed effects of the intra-PFC dopamine antagonist demonstrate a facilitation of VTA BSR and are consistent with the view that PFC dopamine serves a modulatory role over important reward elements within the NAcc. The deferred effects of intra-prefrontal cortex DA receptor blockade on brain stimulation reward thresholds may reflect adaptive responses of subcortical structures to changes in PFC dopamine neurotransmission. It has been suggested that neural adjustments of this type may underlie long term changes in central nervous system functioning brought about by disease, drug use or behavioral conditioning.

Analysis of Variance↗
PubMed2000

Reward deficiency syndrome: genetic aspects of behavioral disorders.

The dopaminergic and opioidergic reward pathways of the brain are critical for survival since they provide the pleasure drives for eating, love and reproduction; these are called 'natural rewards' and involve the release of dopamine in the nucleus accumbens and frontal lobes. However, the same release of dopamine and production of sensations of pleasure can be produced by 'unnatural rewards' such as alcohol, cocaine, methamphetamine, heroin, nicotine, marijuana, and other drugs, and by compulsive activities such as gambling, eating, and sex, and by risk taking behaviors. Since only a minority of individuals become addicted to these compounds or behaviors, it is reasonable to ask what factors distinguish those who do become addicted from those who do not. It has usually been assumed that these behaviors are entirely voluntary and that environmental factors play the major role; however, since all of these behaviors have a significant genetic component, the presence of one or more variant genes presumably act as risk factors for these behaviors. Since the primary neurotransmitter of the reward pathway is dopamine, genes for dopamine synthesis, degradation, receptors, and transporters are reasonable candidates. However, serotonin, norepinephrine, GABA, opioid, and cannabinoid neurons all modify dopamine metabolism and dopamine neurons. We have proposed that defects in various combinations of the genes for these neurotransmitters result in a Reward Deficiency Syndrome (RDS) and that such individuals are at risk for abuse of the unnatural rewards. Because of its importance, the gene for the [figure: see text] dopamine D2 receptor was a major candidate gene. Studies in the past decade have shown that in various subject groups the Taq I A1 allele of the DRD2 gene is associated with alcoholism, drug abuse, smoking, obesity, compulsive gambling, and several personality traits. A range of other dopamine, opioid, cannabinoid, norepinephrine, and related genes have since been added to the list. Like other behavioral disorders, these are polygenically inherited and each gene accounts for only a small per cent of the variance. Techniques such as the Multivariate Analysis of Associations, which simultaneously examine the contribution of multiple genes, hold promise for understanding the genetic make up of polygenic disorders.

Attention Deficit Disorder with Hyperactivity↗
PubMed2001

Novel monoamine transporter ligands reduce cocaine-induced enhancement of brain stimulation reward.

Six novel monoamine reuptake inhibitors were screened for their intrinsic effects on brain stimulation reward (BSR), as well as for their potential to reduce cocaine-induced reward-enhancement in that paradigm. Two of the compounds, nocaine-3B and 5-ara-74A (disubstituted piperidines) significantly reduced locus of rise (LOR), threshold measure of reward, at some doses. One compound, 1-RV-96A (a hybrid of the GBR and WIN-like agents) significantly reduced reward (increased LOR), but only at the highest dose tested. No effect of dose was found for MC9-20 (a GBR-like acyclic analogue of the N-bisarylmethoxyethyl-N'-phenylpropyl piperazine), nocaine-250B or 4-ara-42C (disubstituted piperidines). When cocaine (10 mg/kg, ip) and selected, hedonically neutral doses of novel compounds were combined, the following findings were obtained: MC9-20 (2.5 mg/kg, ip) showed a significant increase in cocaine-induced reward enhancement (0.2 log units or 53%). In contrast, nocaine-250B and 1-RV-96A (both at 10 mg/kg, ip) demonstrated a significant reduction (0.13 log units or 41%) in cocaine-induced reward enhancement (P<.01 and P<.05, respectively), as measured by changes in LOR. There were no differences in the maximum behavioral output (MAX) at either dose of each of the six drugs, or when selected doses were combined with cocaine. These results indicate that nocaine-250B and 1-RV-96A constitute two potential anticocaine compounds worthy of further behavioral and biochemical evaluation.

Animals↗
PubMed1999

The effects of neonatal cocaine exposure on a play-rewarded spatial discrimination task in juvenile rats.

This study examined the effects of neonatal cocaine exposure on the rewarding properties of play in a modified T-maze. Animals were artificially reared from postnatal day (PND) 4-9 with drug concentrated in four daily feeds. There were four treatment groups, 40 mg/kg/day cocaine, 20 mg/kg/day cocaine, an artificially reared control and a surgery control. From PND 38-42, subjects were tested with a food reward (EXP 1) or a play reward (EXP 2). No deficits in learning were seen when the reward was food. The 20 mg/kg/day cocaine group, however, showed impaired learning and altered play behavior when the reward was access to a play partner. Neonatal cocaine exposure thus appears to differentially affect learning based on the type of reward presented.

Animals↗
PubMed2002

Chronic intermittent amphetamine pretreatment enhances future appetitive behavior for drug- and natural-reward: interaction with environmental variables.

Appetitive behavior for drug and sexual reward is enhanced in animals with a history of amphetamine-experience. The present experiment investigated whether prior exposure to a sensitizing regimen of amphetamine treatment would 'globally' enhance future appetitive behaviors of adult male Sprague-Dawley rats, and whether the drug preexposure-environment or intermittency of administration would affect this development. Reward appetite was compared in drug-experienced versus drug-naive rats using amphetamine place-preference conditioning (CPP) and a natural-incentive sensitization task, which measured appetitive approach for food and sexual reward. Experiment I found that 10 daily exposures to 1 mg/kg amphetamine did not alter future psychostimulant CPP, regardless of abstinence schedule. Although daily exposure to a higher amphetamine dose also did not alter appetitive behavior when measured after 2-weeks drug abstinence in Experiment II, alternate-day amphetamine experience (5.0 mg/kg, twice-a-day) in an initially unfamiliar environment persistently enhanced future amphetamine CPP and appetitive behavior for natural reward. Identical treatment administered in the homecage did not. Furthermore, sensitized reward-seeking behaviors were not globally evident. Animals that showed sensitized amphetamine CPP did not show sensitized food-seeking behavior and vice versa. Thus, the environment surrounding chronic psychostimulant drug experience can greatly affect subsequent reward appetite, but the sensitized expression may be individually determined.

Amphetamine↗
PubMed1992

The function relating the subjective magnitude of brain stimulation reward to stimulation strength varies with site of stimulation.

A two-lever choice paradigm with concurrent variable interval schedules of reward was used to measure the growth in the subjective magnitude of reward as a function of current, by finding the adjustment in the stimulating current required to offset a given difference in the rates at which two rewards were received. Increasing current by a factor of 2 increased subjective reward magnitude by a factor ranging from as little as 3 to as much as 4,000. This range was about as great between electrodes within one rat as between electrodes and rats. In the light of earlier findings regarding the equivalent effects of increments is current and pulse frequency, these large differences cannot readily be explained by differing fiber densities at the site of stimulation. It is suggested that the medial forebrain bundle terminates in more than one spatio-temporal integration mechanism. The magnitude of the spatio-temporally integrated effect of a barrage of action potentials in the reward-relevant axons depends on which subset of reward-relevant axons is excited by the stimulation.

Action Potentials↗
PubMed1997

Short-term memory for food reward magnitude: the role of the prefrontal cortex.

Memory for magnitude of reinforcement was assessed in rats using a go/no-go short-term memory paradigm. During the task's study phase rats were given a piece of cereal comprised of either 25 or 50% sugar. For all trials, one of the cereal types was designated positive, the other negative. On the ensuing test phase the rat was presented with an object which covered a food well. If a positive food reward was given during the study phase, a second food reward was placed beneath the object. No food reward was placed under the object if the study phase consisted of a negative food reward. Latency to object displacement was used as the measure of performance. Following the establishment of a significant difference between latency to approach the object with reward compared to latency to approach the object without reward, rats were given either agranular insular cortex, anterior cingulate cortex, pre- and infralimbic cortex or control lesions. Agranular insular cortex lesioned animals demonstrated a mild post-surgery impairment. Trials consisting of 10 and 20 s delays between the study and test phases were then introduced. Delays exacerbated the previous deficit of the agranular insular cortex lesion group, but had little effect on the other lesion groups. All animals transferred to a new set of cereals containing 25 and 50% sugar and exhibited taste preferences to sugar solutions of different concentrations. These results indicate that the agranular insular cortex may play an important role in the processing of affect-laden information within a prefrontal cortex short-term or working memory system.

Animals↗
PubMed2001

Fluoxetine combined with a serotonin-1A receptor antagonist reversed reward deficits observed during nicotine and amphetamine withdrawal in rats.

The symptom of "diminished interest or pleasure" in rewarding stimuli is an affective symptom of nicotine and amphetamine withdrawal, and a core symptom of depression. An operational measure of this symptom is elevation of brain reward thresholds during drug withdrawal. We report here that acute co-administration of fluoxetine, a selective serotonin reuptake inhibitor, and p-MPPI, a serotonin-1A receptor antagonist, alleviated the diminished interest in brain stimulation reward observed during withdrawal from nicotine or amphetamine in rats (i.e., increased reward). By contrast, the same drug combination treatment did not reduce the somatic signs of nicotine withdrawal indicating symptom-specific neurobiological abnormalities. Surprisingly, the same treatment had opposite effects in control rats where reductions in reward were produced, suggesting that animal models should be based primarily on studying specific deficits that are pathognomic of a psychiatric disorder. The reversal of the affective aspects of drug withdrawal by a treatment that enhances serotonin neurotransmission indicates that decreased serotonergic function may mediate the reward decrements characterizing nicotine and amphetamine withdrawal, and that these symptoms may be homologous to a core symptom of non-drug-induced depressions.

Aminopyridines↗
PubMed2001

Beautiful faces have variable reward value: fMRI and behavioral evidence.

The brain circuitry processing rewarding and aversive stimuli is hypothesized to be at the core of motivated behavior. In this study, discrete categories of beautiful faces are shown to have differing reward values and to differentially activate reward circuitry in human subjects. In particular, young heterosexual males rate pictures of beautiful males and females as attractive, but exert effort via a keypress procedure only to view pictures of attractive females. Functional magnetic resonance imaging at 3 T shows that passive viewing of beautiful female faces activates reward circuitry, in particular the nucleus accumbens. An extended set of subcortical and paralimbic reward regions also appear to follow aspects of the keypress rather than the rating procedures, suggesting that reward circuitry function does not include aesthetic assessment.

Adult↗
PubMed2003

A region of mesial prefrontal cortex tracks monetarily rewarding outcomes: characterization with rapid event-related fMRI.

The function of the mesial prefrontal cortex (MPFC: including Brodman areas 10/12/32) remains an enigma. Current theories suggest a role in representing internal information, including emotional introspection, autonomic control, and a "default state" of semantic processing. Recent evidence also suggests that parts of this region may also play a role in processing reward outcomes. In this study, we investigated the possibility that a region of the MPFC would be preferentially recruited by monetary reward outcomes using a parametric monetary incentive delay (MID) task. Twelve healthy volunteers participated in functional magnetic resonance scans while playing the MID task. Group analyses indicated that while the ventral striatum was recruited by anticipation of monetary reward, a region of the MPFC instead responded to rewarding monetary outcomes. Specifically, volume-of-interest analyses indicated that when volunteers received $5.00 after anticipating a $5.00 win, MPFC activity increased, whereas when volunteers did not receive $5.00 after anticipating a $5.00 win, MPFC activity decreased, relative to outcomes with no incentive value. These findings suggest that in the context of processing monetary rewards, a region of the MPFC preferentially tracks rewarding outcomes.

Adult↗
PubMed2001

Pathological gamblers, with and without substance use disorders, discount delayed rewards at high rates.

Pathological gambling is classified as a disorder of impulse control, yet little research has evaluated behavioral indices of impulsivity in gamblers. The rates at which rewards delayed in time are subjectively devalued may be a behavioral marker of impulsivity. This study evaluated delay discounting in 60 pathological gamblers and 26 control participants. Gamblers were divided into those with (n = 21) and without (n = 39) substance use disorders. A hypothetical $1,000 reward was delayed at intervals ranging from 6 hr to 25 years, and immediate rewards varied from $1 to $999. Pathological gamblers discounted delayed rewards at higher rates than control participants, and gamblers with substance use disorders discounted delayed rewards at higher rates than non-substance-abusing gamblers. These data provide further evidence that rapid discounting of delayed rewards may be a feature central to impulse control and addictive disorders, including pathological gambling.

Adult↗
PubMed1976

Effects of self-esteem and expected duration of interaction on liking for a highly rewarding partner.

Psychological theories predicated on the assumption of human selfishness and theories based on principles of equity may lead to conflicting predictions about when a person will like his partner. Of special interest are a person's reactions to receiving uncommonly high rewards. The present study addressed this issue by examing the development of same-sex liking in 40 female college students. It was hypothesized that subjects with lowered self-esteem, having a great need for interpersonal rewards, would react favorably to the receipt of such rewards, even if underserved. Subjects with raised self-esteem, on the other hand, having had their need for rewards met, should respond unfavorably to the receipt of high rewards, desiring a more equitable distribution of reward. These effects should be strong only when continuing dyadic interaction is expected (i.e., as issues of stability and reciprocity become salient). The predictions were confirmed.

Adult↗
PubMed1986

Social influences on creativity: the effects of contracted-for reward.

Three studies were conducted to examine the effects of reward on children's and adult's creativity. The primary hypothesis was that explicitly contracting to do an activity in order to receive a reward will have negative effects on creativity, but receiving no reward or only a noncontracted-for reward will have no such negative effects. All three studies provided support for this hypothesis. Moreover, this support appears to be strong and generalizable across different subject populations, reward types, reward presentations, and creativity tasks. Possible mechanisms for the phenomenon are discussed.

Achievement↗
PubMed1986

Rewarding elementary schoolchildren for their use of safety belts.

This study reports on the application of reward procedures to elementary schoolchildren to increase their use of seat belts en route to two schools. Following strict rules for assessing buckle-up compliance, all passengers in a car had to be safely secured in order for the schoolchildren to receive rewards. Compliant children received paper slips as they arrived at schools, which were redeemable for stickers, bumper stickers, and coloring books. The slips were also used in weekly drawings for pizza dinners. The mean compliance rate for School 1 was 4.3% during baseline, 66.2% for the reward phase across 4 weeks, 60% for return to baseline, 17.2% for Follow-Up 1, and 8.5% for Follow-Up 2. For School 2, the mean percentage was 5.3% at baseline, 69.8% for the reward phase, 68.5% for return to baseline, 40.1% for Follow-Up 1, and 20% for Follow-Up 2. These results indicate that rewarding the schoolchildren increased their own seat-belt use as well as that of their adult drivers and other passengers. Decreases in usage were observed after the rewards were removed.

Child↗
PubMed1993

Subjective reward magnitude of medial forebrain stimulation as a function of train duration and pulse frequency.

The growth of the subjective reward magnitude of medial forebrain bundle stimulation in the rat (Sprague-Dawley) as a function of train duration and pulse frequency was measured in 2 ways: (a) a titration method, which used differences in rate of reward on 2 levers to compensate for differences in the magnitude of the rewards; and (b) a direct method, in which the ratio of the reward magnitudes at the 2 levers was assumed to be given by the ratio of times spent on each lever. The results of the 2 methods agree. Reward magnitude grows as approximately a power function of train duration up to train durations of about 1 s, then declines somewhat over the interval from 2-20 s. The exponent of growth varies from 0.4 to 2.3. With stronger stimulation (higher pulse frequency), peak reward magnitude is bigger, but the saturating train duration is approximately the same.

Animals↗
PubMed1994

Saturation of subjective reward magnitude as a function of current and pulse frequency.

In rats with electrodes in the medial forebrain bundle, the upper portion of the function relating the experienced magnitude of the reward to pulse frequency was determined at currents ranging from 100 to 1,000 microA. The pulse frequency required to produce an asymptotic level of reward was inversely proportional to current except at the lowest currents and highest pulse frequencies. At a given current, the subjective reward magnitude functions decelerated to an asymptote over an interval in which the pulse frequency doubled or tripled. The asymptotic level of reward was approximately constant for currents between 200 and 1,000 microA but declined substantially at currents at or below 100 microA and pulse frequencies at or above 250 to 400 pulses per second. The results are consistent with the hypothesis that the magnitude of the experienced reward depends only on the number of action potentials generated by the train of pulses in the bundle of reward-relevant axons.

Animals↗
PubMed2006

A reaction-time paradigm to measure reward-oriented bias in rats.

The authors devised a nose-poke task with asymmetric position-reward mapping to distinguish between effects of bias and sensitivity in reaction times of rats. In all trials, the rats had to poke their noses into the hole to the left or to the right of center, corresponding to the side at which 4 lights were illuminated, while ignoring distracters on the other side. Reaction times were faster for large-reward trials than for small-reward trials. In large-reward trials, there was no influence of the number of distracters, whereas in small-reward trials, distracters produced an increase in reaction time. Analysis of reaction-time distributions according to a linear model of decision making suggests that most of the systematic variability was due to a reward-oriented bias.

Animals↗
PubMed2004

Delay discounting of potentially real and hypothetical rewards: II. Between- and within-subject comparisons.

Prior studies comparing discounting of delayed hypothetical or potentially real rewards have reported no differences, but they used within-subjects designs. This raises the possibility that participants remembered their choices in one condition and repeated them in the other. In Experiment 1, between-subjects comparisons were made with an adjusting-amount procedure. No significant effect of reward type on delay discounting was detected. Experiment 2 increased the proportion of real rewards and made between- and within-subject comparisons. These comparisons also failed to reveal a significant effect of reward type. Although these findings are consistent with prior findings, caution is urged because choices involving hypothetical rewards have yet to be compared with choices involving real rewards (i.e., the consequences of every choice are obtained) in an experiment using forced-choice trials and steady-state methodology.

Adolescent↗