Timeout Periods Research Articles

The ascending limb of the cocaine unit dose–response function in rats as an experimental artifact

The cocaine unit dose–response function is an inverted U with the ascending and descending limbs representing the positive and rate limiting cocaine effects, respectively. Higher fixed ratio (FR) schedules and/or time-out periods make the ascending limb more prominent. Alternatively, a pharmacokinetic/pharmacodynamic interaction theory demonstrates that cocaine-induced lever pressing occurs only when cocaine levels are within a range termed the compulsion zone. The inter-injection intervals of self-administration increase with cocaine unit dose because of the longer time required to eliminate higher doses. However, this theory has not been applied to high FR schedules. Rats acquired cocaine self-administration on a FR1 schedule and then were changed to sessions that started with both FR1 and then FR50 over a range of unit doses with a set number of self-administrations allowed for each dose. On FR1, rats completed the maximum number of injections at all but the lowest unit dose. In contrast, on FR50 the proportion of the permitted injections increased as a function of unit dose. However, this ascending limb was the result of averaging data from sessions where rats completed or failed to complete the allowed number of injections. Rats completed all injections when cocaine levels were maintained in the compulsion zone. The FR50 schedule and low unit doses decreased this probability of maintaining cocaine levels in the compulsion zone when the rate of cocaine elimination exceeded the rate of cocaine input during the time required to complete the 50 presses. It is concluded that the ascending limb is an experimental artifact and that the entire dose–response function and the FR50-induced increase in inter-injection intervals are explained in terms of the compulsion zone theory of cocaine self-administration behavior.

Assessing the Implementation of School Discipline Policy in Ghanaian Basic Schools

As part of the effort to create safer and more protective learning environments in Ghanaian schools, the Ghana Education Service in 2017 officially banned all forms of corporal punishment and required teachers to adopt a positive discipline toolkit based on a manual prescribed as an alternative to corporal punishment. This study sought to investigate the implementation of the alternative positive discipline policy in the basic schools of Ghana. The study utilized qualitative research approach to gather data from 15 teachers through semi-structured interviews. Based on thematic analysis, the study showed that the teachers used many discipline methods per the policy on school discipline. They included writing lines, manual work, physical punishments, time-out periods, classroom rules, appointment and withdrawal of positions, and counselling to manage students’ behavior. The study, however, found that teachers perceive the positive discipline methods to be ineffective in managing students’ behavior compared to the use of corporal punishment. The implication drawn from the study was that despite the use of some alternative discipline methods by the teachers, they have not abandoned all forms of corporal punishments in schools. The study therefore recommended, among other things, that school leaders and other authorities institute surveillance and monitoring systems to check violators and sanction teachers who refuse to employ the non-violent discipline methods prescribed by the Ghana Education Service.

When Failure is Neither Fatal nor Final: Understanding Re-internationalization Processes

Re-internationalization, or firms’ re-entry into international operations after completely withdrawing from initial international business failures, is a neglected phenomenon in international business research. This research develops theoretical underpinnings for understanding re-internationalization processes through an inductive theory-building approach using case studies of four Indian firms from diverse industries. We examine various aspects of firms’ initial internationalization, including the learning and experiences gained during such activities, the role of networks and relationships, valences in organizational commitment to internationalization during the exit and time-out periods, and the significance of dynamic capabilities that facilitate successful re-internationalization of firms. Our theorizing is relevant for scholars seeking a better understanding of the re-internationalization processes and for practitioners seeking insights for decision-making related to internationalization strategies. Our findings also have implications for policymakers responsible for designing subventions and incentives for both internationalization and re-internationalization.

AORN Position Statement on Managing Distractions and Noise During Perioperative Patient Care

<scp>AORN</scp> Position Statement on Managing Distractions and Noise During Perioperative Patient Care

Delta‐9‐tetrahydrocannabinol (THC) Enhances Heroin‐Induced Antinociception and Disruptions of Learning and Performance in Rhesus Macaques

Cannabinoid administration prior to opioid administration can produce opioid‐sparing antinociceptive effects in several species by reducing the dosage of opioid needed to produce effective antinociception. These potentially valuable clinical effects could be undermined, however, if the cannabinoids also enhance the disruptive effects of opioids on neurobehavioral function. To address this question, the combined effects of THC and heroin were examined in nonhuman primates (rhesus macaques, n=4) responding in a learning and performance task and concurrently exposed to a tail‐withdrawal antinociception procedure. Testing in this case was facilitated by examining 4 discrete cycles of acquisition and performance that were separated by timeout periods to facilitate tail‐withdrawal tests and cumulative dosing. Each cycle included a 10‐min time out period for drug onset, a 15‐min acquisition component, and a 5‐min performance component. In the learning and performance task, subjects acquired a new 5‐response key‐sequence, or emitted a well‐rehearsed 5‐response key‐sequence, respectively. Responding in both components of the task was reinforced with a food pellet after every three completions of the sequence (i.e., a second‐order fixed‐ratio [FR3] schedule of food reinforcement). Warm‐water tail‐withdrawal antinociception was measured using three water temperatures (40°, 50°, and 55°C). Heroin alone dose‐dependently decreased response rates in the acquisition and performance components without markedly increasing percent errors. When the opioid antagonist naltrexone (1 mg/kg) preceded the cumulative heroin injections, the heroin dose‐effect curves for both the behavioral disruptions and antinociception were shifted rightward indicating both effects were mediated by mu‐opioid receptors. In contrast, THC alone disrupted both behaviors at doses that had no antinociceptive effect, but it shifted the heroin dose‐effect curves for learning, performance, and antinociception leftward. Overall, these data demonstrate that THC produces its opioid‐sparing antinociceptive effects at doses that are behaviorally disruptive alone and in combination with heroin.Support or Funding InformationThis work was supported by a National Institute of Drug Abuse Fellowship (F32DA47013‐01)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Potential energy savings from high-resolution sensor controls for LED lighting

LED lighting systems paired with high-resolution sensor systems offer great potential for substantial energy savings via enhanced control options, and have other value-added features. We used modelling and demonstrations in a full-scale office test bed to illustrate this potential. First, we propose that such a system enables much shorter timeout periods for occupancy sensing: the higher density of sensors provides more reliable occupancy detection and LEDs are impervious to lifetime degradation from the consequent increased switching frequency. We used occupancy data measured in real office environments to estimate that a reduction in timeout period from the current code maximum of 20min to 1min would yield 26% additional energy savings. Further, we installed 72 LED luminaires in an office test bed with windows; each luminaire featured a co-located motion sensor and light sensor. The localized light sensor enabled daylight harvesting at each fixture to be optimized to local spatial conditions, yielding an extra 35% energy savings compared to a single photosensor controlling all luminaires, and ensuring better delivery of target horizontal illuminance values across the space. Finally, we demonstrated a combination of local occupancy and daylight harvesting features that resulted in 79% energy savings compared to typical prevailing energy code provisions for open-plan offices.

Operant conditioning of neural activity in freely behaving monkeys with intracranial reinforcement.

Operant conditioning of neural activity has typically been performed under controlled behavioral conditions using food reinforcement. This has limited the duration and behavioral context for neural conditioning. To reward cell activity in unconstrained primates, we sought sites in nucleus accumbens (NAc) whose stimulation reinforced operant responding. In three monkeys, NAc stimulation sustained performance of a manual target-tracking task, with response rates that increased monotonically with increasing NAc stimulation. We recorded activity of single motor cortex neurons and documented their modulation with wrist force. We conditioned increased firing rates with the monkey seated in the training booth and during free behavior in the cage using an autonomous head-fixed recording and stimulating system. Spikes occurring above baseline rates triggered single or multiple electrical pulses to the reinforcement site. Such rate-contingent, unit-triggered stimulation was made available for periods of 1-3 min separated by 3-10 min time-out periods. Feedback was presented as event-triggered clicks both in-cage and in-booth, and visual cues were provided in many in-booth sessions. In-booth conditioning produced increases in single neuron firing probability with intracranial reinforcement in 48 of 58 cells. Reinforced cell activity could rise more than five times that of non-reinforced activity. In-cage conditioning produced significant increases in 21 of 33 sessions. In-cage rate changes peaked later and lasted longer than in-booth changes, but were often comparatively smaller, between 13 and 18% above non-reinforced activity. Thus intracranial stimulation reinforced volitional increases in cortical firing rates during both free behavior and a controlled environment, although changes in the latter were more robust.NEW & NOTEWORTHY Closed-loop brain-computer interfaces (BCI) were used to operantly condition increases in muscle and neural activity in monkeys by delivering activity-dependent stimuli to an intracranial reinforcement site (nucleus accumbens). We conditioned increased firing rates with the monkeys seated in a training booth and also, for the first time, during free behavior in a cage using an autonomous head-fixed BCI.

Testing the accuracy of low-cost data streams for determining single-person office occupancy and their use for energy reduction of building services

We explored methods of detecting occupancy in single-person offices using data already collected by the occupant’s PC, or data from relatively cheap sensors added to the PC. We collected data at 15-s intervals for up to 31 days in each of 28 offices. A combination of low/no cost sensors (webcam-based motion detection, and keyboard and mouse activity) was much more accurate at detecting occupancy than a commercial ceiling-based passive infrared (PIR) sensor, and provided overall daytime accuracy >90%, with very low false negative rates. This enhanced detection performance would enable a reduction in the timeout periods for building service curtailment on space vacancy. For example, lighting switch-off timeout could be reduced from the current energy code standard of 20min to less than 5min, increasing energy savings potential by 25–45%. We then deployed this system in a proof-of-concept demonstration, using it to control lighting, heating, ventilation, and air conditioning (HVAC), and plug loads in a mock-up office environment. Tests were run over nine occupied days (six in cooling season, three in heating season). The system delivered energy savings of 15–68%, with no reported false negative errors.

Effects of various cannabinoid ligands on choice behaviour in a rat model of gambling.

It is estimated that 0.6–1% of the population in the USA and Canada fulfil the Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM-5) criteria for gambling disorders (GD). To date, there are no approved pharmacological treatments for GD. The rat gambling task (rGT) is a recently developed rodent analogue of the Iowa gambling task in which rats are trained to associate four response holes with different magnitudes and probabilities of food pellet rewards and punishing time-out periods. Similar to healthy human volunteers, most rats adopt the optimal strategies (optimal group). However, a subset of animals show preference for the disadvantageous options (suboptimal group), mimicking the choice pattern of patients with GD. Here, we explored for the first time the effects of various cannabinoid ligands (WIN 55,212-2, AM 4113, AM 630 and URB 597) on the rGT. Administration of the cannabinoid agonist CB1/CB2 WIN 55,212-2 improved choice strategy and increased choice latency in the suboptimal group, but only increased perseverative behaviour, when punished, in the optimal group. Blockade of CB1 or CB2 receptors or inhibition of fatty-acid amide hydrolase did not affect rGT performance. These results suggest that stimulation of cannabinoid receptors could affect gambling choice behaviours differentially in some subgroups of subjects.

Dopamine D3 Receptors Modulate the Ability of Win-Paired Cues to Increase Risky Choice in a Rat Gambling Task.

Similar to other addiction disorders, the cues inherent in many gambling procedures are thought to play an important role in mediating their addictive nature. Animal models of gambling-related behavior, while capturing dimensions of economic decision making, have yet to address the impact that these salient cues may have in promoting maladaptive choice. Here, we determined whether adding win-associated audiovisual cues to a rat gambling task (rGT) would influence decision making. Thirty-two male Long-Evans rats were tested on either the cued or uncued rGT. In these tasks, animals chose between four options associated with different magnitudes and frequencies of reward and punishing time-out periods. As in the Iowa Gambling Task, favoring options associated with smaller per-trial rewards but smaller losses and avoiding the tempting "high-risk, high-reward" decks maximized profits. Although the reinforcement contingencies were identical in both task versions, rats' choice of the disadvantageous risky options was significantly greater on the cued task. Furthermore, a D3 receptor agonist increased choice of the disadvantageous options, whereas a D3 antagonist had the opposite effects, only on the cued task. These findings are consistent with the reported role of D3 receptors in mediating the facilitatory effects of cues in addiction. Collectively, these results indicate that the cued rGT is a valuable model with which to study the mechanism by which salient cues can invigorate maladaptive decision making, an important and understudied component of both gambling and substance use disorders. Significance statement: We used a rodent analog of the Iowa Gambling Task to determine whether the addition of audiovisual cues would affect choice preferences. Adding reward-concurrent cues significantly increased risky choice. This is the first clear demonstration that reward-paired cues can bias cost/benefit decision making against a subject's best interests in a manner concordant with elevated addiction susceptibility. Choice on the cued task was uniquely sensitive to modulation by D3 receptor ligands, yet these drugs did not alter decision making on the uncued task. The relatively unprecedented sensitivity of choice on the cued task to D3-receptor-mediated neurotransmission data suggest that similar neurobiological processes underlie the ability of cues to both bias animals toward risky options and facilitate drug addiction.

Cocaine self-administration behavior in inbred mouse lines segregating different capacities for inhibitory control

Various dimensions of impulsivity have been linked to substance abuse and dependence, both as consequences of, and as predisposing factors to addiction. With respect to the latter, they may be quantitative indicators of liability for substance use disorders (SUD) and aid in determining underlying genetic influences. We have previously determined that inhibitory control over impulsive responding, as measured by a reversal learning task, is heritable and under substantial genetic control, however their role as explaining variables for aspects of SUD have not been well explored. The aim of this study was to test for an association between genetically determined differences in inhibitory control and addiction-related phenotypes, such that phenotypes of poor inhibitory control would predict propensity for elevated operant drug-seeking and -taking behaviors. Mice from BxD strains with either good reversal learning (GRL) or poor reversal learning (PRL) ability were tested for intravenous cocaine self-administration under FR1, FR2, and FR5 reinforcement schedules. Additionally, locomotor responses to experimenter-delivered cocaine were assessed. Compared to GRL strains, PRL strains acquired self-administration behavior more rapidly and administered cocaine at greater rates under all schedules of reinforcement, without any differences in discrimination index. In addition, PRL mice also exhibited increased responding during time-out periods. PRL strains also showed larger locomotor responses to 10 or 20 mg/kg injections of cocaine. These studies demonstrate that heritable strain differences in inhibitory control do influence drug self-administration, thus suggest that genetically driven impulsivity of this type may predispose susceptibility to drug abuse and addiction.

Systemic Administration of 8-OH-DPAT and Eticlopride, but not SCH23390, Alters Loss-Chasing Behavior in the Rat

Gambling to recover losses is a common gaming behavior. In a clinical context, however, this phenomenon mediates the relationship between diminished control over gambling and the adverse socioeconomic consequences of gambling problems. Modeling loss-chasing through analogous behaviors in rats could facilitate its pharmacological investigation as a potential therapeutic target. Here, rats were trained to make operant responses that produced both food rewards, and unpredictably, imminent time-out periods in which rewards would be unavailable. At these decision points, rats were offered choices between waiting for these time-out periods to elapse before resuming responding for rewards ('quit' responses), or selecting risky options with a 0.5 probability of avoiding the time-outs altogether and a 0.5 probability of time-out periods twice as long as signaled originally ('chase' responses). Chasing behavior, and the latencies to chase or quit, during sequences of unfavorable outcomes were tested following systemic administration of the 5-HT1A receptor agonist, 8-OH-DPAT, the D2 receptor antagonist, eticlopride, and the D1 receptor antagonist, SCH23390. 8-OH-DPAT and eticlopride significantly reduced the proportion of chase responses, and the mean number of consecutive chase responses, in a dose-dependent manner. 8-OH-DPAT also increased latencies to chase. Increasing doses of eticlopride first speeded, then slowed, latencies to quit while SCH23390 had no significant effects on any measure. Research is needed to identify the precise cognitive mechanisms mediating these kinds of risky choices in rats. However, our data provide the first experimental demonstration that 5-HT1A and D2, but not D1, receptor activity influence a behavioral analog of loss-chasing in rats.

Smoking spaces and practices in pubs, bars and clubs: Young adults and the English smokefree legislation

Young adulthood is an important but overlooked period in the development of smoking behaviour. We know little about the impact of smokefree policies on this group. In a secondary analysis of longitudinal, qualitative interview data we explore smoking practices in young adulthood, the role of smoking in the spaces of the night-time economy, and the impact of smokefree legislation. Participants carefully managed their smoking in different spaces in relation to the self they wished to present. This was shaped by the transitional nature of young adulthood. Smoking played a role in constructing time-out periods from the demands of everyday life in a similar way to alcohol use. The restrictions imposed by the smokefree legislation quickly became normal for most; however, the experience of smoking was influenced by the nature and quality of smoking spaces. The re-spatialisation of smoking necessitated by the smokefree legislation may reaffirm processes of social denormalisation and stigmatisation of smoking, whilst simultaneously allowing young adult smokers to produce, in some contexts, a positive, fun, sociable smoker identity.

The Motivation to Self-Administer is Increased After a History of Spiking Brain Levels of Cocaine

Recent attempts to model the addiction process in rodents have focused on cocaine self-administration procedures that provide extended daily access. Such procedures produce a characteristic loading phase during which blood levels rapidly rise and then are maintained within an elevated range for the duration of the session. The present experiments tested the hypothesis that multiple fast-rising spikes in cocaine levels contribute to the addiction process more robustly than constant, maintained drug levels. Here, we compared the effects of various cocaine self-administration procedures that produced very different patterns of drug intake and drug dynamics on Pmax, a behavioral economic measure of the motivation to self-administer drug. Two groups received intermittent access (IntA) to cocaine during daily 6-h sessions. Access was limited to twelve 5-min trials that alternated with 25-min timeout periods, using either a hold-down procedure or a fixed ratio 1 (FR1). Cocaine levels could not be maintained with this procedure; instead the animals experienced 12 fast-rising spikes in cocaine levels each day. The IntA groups were compared with groups given 6-h FR1 long access and 2-h short access sessions and two other control groups. Here, we report that cocaine self-administration procedures resulting in repeatedly spiking drug levels produce more robust increases in Pmax than procedures resulting in maintained high levels of cocaine. These results suggest that rapid spiking of brain-cocaine levels is sufficient to increase the motivation to self-administer cocaine.

P.2.005 The role of adolescent social behaviour in the development of impulse control in rats

Adolescence is a critical developmental period, during which maturational changes in the brain are associated with age-specific behavioral characteristics, to facilitate the transition into adulthood. Similar to human children, most young mammals spend a substantial part of postweaning development engaging in play with peers, such as running, chasing, climbing and play fighting. Play experience in a social context is crucial for the development of adaptive socio-affective responses and the acquisition of cognitive skills [1]. Conversely, social deficits are a core symptom of neuropsychiatric disorders that are apparent during childhood and adolescence, such as autism, early-onset schizophrenia, and disruptive behavior disorders. In the present study, we investigated the importance of social interaction during adolescence for the development of impulse control and decision making in rats. To that aim, rats were socially isolated for several weeks during adolescence, subsequently group-housed, and impulsive behavior and decision making were tested in adulthood. Two behavioral dimensions of impulsivity were measured, i.e. inhibitory control using the five-choice serial reaction time task (5-CSRTT) and impulsive choice using the delayed reward task (DRT). In the 5CSRT task, rats are required to wait during an inter-trial interval (ITI) while scanning a horizontal array of five apertures, and to nose poke in the spatial location of a brief visual stimulus in order to earn food reward. The number of responses before the onset of the visual stimulus, i.e. premature responses, is regarded as a measure of impulsivity. In the DRT, rats are faced with a choice between two response options. One option is associated with a small, immediate food reward, whereas the second option results in a larger delayed, but economically optimal food reward. Impulsive choice is associated with a higher preference for the small, immediate reward. Decision making was determined using the rat Gambling Task (rGT). In this paradigm, rats choose among four different options to earn as many sugar pellets as possible within a limited amount of time. Each option is associated with the delivery of a different amount of reward, probability and duration of punishing time-out periods during which reward cannot be earned. Monoaminergic involvement in task performance was investigated using systemic administration of the psychostimulant drug amphetamine, dopamine reuptake inhibitor GBR12909, noradrenaline reuptake inhibitor atomoxetine and serotonin reuptake inhibitor citalopram. The results show that socially isolated rats display hypersensitivity to an impulse control challenge (long intertrial interval), and insensitivity to GBR12909 in the 5CSRTT. No major long-term effects of adolescent social isolation on impulsive choice and decision making were found. These data indicate that adolescent social isolation induces a subtle, but selective impairment in inhibitory control, associated with altered dopamine function in rats. Social interaction during adolescence serves to facilitate the development of inhibitory control capacities.

Brain-Cocaine Concentrations Determine the Dose Self-Administered by Rats on a Novel Behaviorally Dependent Dosing Schedule

A novel behaviorally dependent dosing (BDD) schedule was used to examine the relationship between doses of cocaine self-administered by rats and brain drug levels within a session. The BDD schedule used a hold-down response to activate a syringe pump. The length of time the lever was held down determined the duration that the syringe pump was activated. In the first experiment, rats self-administered cocaine for daily 3 h sessions and brain levels of cocaine were modeled using well-established parameters. Although analysis revealed that rats self-administered doses within a predicted range, one extremely large dose was consistently observed at the beginning of each session when brain levels of cocaine were low. In the second experiment, we introduced a range of timeout periods (10-25 min) in order to produce variability in brain-cocaine concentrations. Animals self-administered larger doses immediately following each timeout period and the dose size was inversely correlated with the length of the timeout. These results show that the dose of cocaine that rats self-administer within a session is inversely related to the amount of drug on board.

Is There a Career Penalty for Mothers' Time Out? A Comparison of Germany, Sweden and the United States

This article focuses on three countries with distinct policies toward motherhood and work: Germany, Sweden and the United States. We analyze the length of mothers' time out of paid work after childbirth and the short-term career consequences for mothers. In the United States, we identify a career punishment even for short timeout periods; long time-out periods increase the risk of a downward move and reduce the chances of an upward move. In Germany, long time-out periods destabilize the career and, the longer the leave, the greater the risk of either an upward or downward move. In Sweden, we find a negative effect of time out on upward moves. Hence, even in woman-friendly Sweden, women's career prospects are better if they return to paid work sooner rather than later.

CHANGES IN BLOOD PRESSURE AND HEART RATE DURING FIXED‐INTERVAL RESPONDING IN SQUIRREL MONKEYS

Episodic and sustained increases in heart rate and mean arterial blood pressure can occur with recurring patterns of schedule-controlled behavior. Most previous studies were conducted under fixed-ratio schedules, which maintained a consistent high rate of responding that alternated with periods of no responding during times when the schedule was not in operation. The present study examined changes in heart rate and blood pressure under fixed-interval schedules which maintained a range of rates that varied from little or no responding at the beginning of the fixed interval to high rates at the end of the interval. The relations of cardiovascular function to rate of responding were examined. Squirrel monkeys prepared with arterial catheters were trained to respond under fixed-interval schedules of electric-shock presentation. The duration of the interval was varied across sessions and cardiovascular parameters were examined. Local rates of responding were typically near zero during timeout periods, low at the beginning of each fixed-interval cycle, and then increased as the fixed interval progressed. At most schedule durations, arterial blood pressure and heart rate levels were lowest at the beginning of the interval cycles, increased as the rate of responding increased, and then decreased during the timeout periods. At all parameters studied, there was a direct relationship between changes in response rate within fixed-interval cycles and changes in heart rate and blood pressure. The results suggest that a much closer concordance of these cardiovascular parameters and schedule-controlled responding is obtained by examining ongoing behavior as it occurs within the contingencies by which it is maintained.

Serotonergic and Dopaminergic Modulation of Gambling Behavior as Assessed Using a Novel Rat Gambling Task

Pathological gambling (PG) is characterized by persistent, maladaptive gambling behavior, which disrupts personal and professional life. Animal models of gambling behavior could make a significant contribution to improving our understanding of the neural and neurochemical basis of gambling, and the treatment of PG. When gambling, failing to win critically results in the loss of resources wagered as well as the absence of additional gain. Here, we have incorporated these concepts into a novel rat gambling task (rGT), based, in part, on the 'Iowa' gambling task (IGT) commonly used clinically to measure gambling-like behavior. Rats choose among four different options to earn as many sugar pellets as possible within 30 min. Each option is associated with the delivery of a different amount of reward, but also with a different probability and duration of punishing time-out periods during which reward cannot be earned. The schedules are designed such that persistent choice of options linked with larger rewards result in fewer pellets earned per unit time. Rats learn to avoid these risky options to maximize their earnings, comparable with the optimal strategy in the IGT. Both d-amphetamine and the 5-HT(1A) receptor agonist, 8-OH-DPAT, impaired task performance. In contrast, the dopamine D(2) receptor antagonist, eticlopride, improved performance, whereas the D(1) receptor antagonist, SCH23390, had no effect. These data suggest that both serotonergic and dopaminergic agents can impair and improve gambling performance, and indicate that the rGT will be a useful tool to study the biological basis of gambling.

Sex Differences in Non-Reinforced Responding for Cocaine

Prior studies report no sex differences in cocaine consumption during maintenance of self-administration. We find female rats show poorer lever discrimination during acquisition of self-administration. Now, we test whether female rats show greater non-reinforced or ineffective responding (presses during infusion and time-out periods as well as inactive lever presses) than male rats during maintenance of cocaine self-administration (.0625–1.0 mg/kg/infusion) in Experiment 1. Persistence of responding during extinction when saline-replaced cocaine was also examined. Whether response differences reflect sex differences in movements under a non-drug condition was tested in Experiment 2. Because cocaine may affect lever press rates differentially between sexes, we examined the effects of cocaine (.3–30 mg/kg; IP) on responding for food in Experiment 3. Cocaine consumption does not differ between female and male rats. However, females respond more during infusion and time-out periods and during extinction than males. There is no sex difference in movements and high cocaine doses decrease responding for food more in female vs. male rats. That females engage in more ineffective responding may represent heightened “craving” and cannot be explained by increased movements or cocaine-stimulated increases in lever pressing. In contrast, responding for cocaine in males appears driven by drug delivery.