A quantitative analysis of the reward-enhancing effects of nicotine using reinforcer demand

Reward enhancement by nicotine has been suggested as an important phenomenon contributing toward tobacco abuse and dependence. Reinforcement value is a multifaceted construct not fully represented by any single measure of response strength. The present study evaluated the changes in the reinforcement value of a visual stimulus in 16 male Sprague–Dawley rats using the reinforcer demand technique proposed by Hursh and Silberberg. The different parameters of the model have been shown to represent differing facets of reinforcement value, including intensity, perseverance, and sensitivity to changes in response cost. Rats lever-pressed for 1-min presentations of a compound visual stimulus over blocks of 10 sessions across a range of response requirements (fixed ratio 1, 2, 4, 8, 14, 22, 32). Nicotine (0.4 mg/kg, base) or saline was administered 5 min before each session. Estimates from the demand model were calculated between nicotine and saline administration conditions within subjects and changes in reinforcement value were assessed as differences in Q0, Pmax, Omax, and essential value. Nicotine administration increased operant responding across the entire range of reinforcement schedules tested, and uniformly affected model parameter estimates in a manner suggesting increased reinforcement value of the visual stimulus

Nicotine Enhances Operant Responding for Qualitatively Distinct Reinforcers Under Maintenance and Extinction Conditions

RATIONALE—Nicotine enhancement of reward has been implicated as an important contributor to tobacco addiction. Despite the attention that reward enhancement has received, the behavioral mechanisms whereby nicotine enhances operant responding remain largely unknown. The present study sought to extend previous work by evaluating the effects of nicotine on responding for two qualitatively different rewards (visual stimulation (VS) and 4% sucrose solution) under fixed-ratio (FR) maintenance and extinction conditions. METHOD—Sprague-Dawley rats were trained to press an active lever for VS (Experiment 1) or 4% sucrose solution (Experiment 2) and evaluated over 15 sessions on a FR5 schedule of reinforcement. Nicotine (0.4 mg base/kg, SC) or saline were administered 5 min before each session; the alternate solution was given in the home cage after the session. The effects of nicotine on extinction responding were then assessed over 5 sessions and rats were divided into 4 groups based on drug of injection received during FR-maintenance and extinction phases (Maintenance- Extinction): Nic-Nic, Nic-Sal, Sal-Sal, and Sal-Nic. RESULTS—Nicotine increased active lever response rates for both VS and 4% sucrose under FR5 maintenance conditions. Nicotine also increased response rates in the Nic-Nic group relative to all other groups under extinction conditions in both experiments, though this effect had greater longevity following VS maintenance conditions than sucrose. Enhancement of responding during extinction does not appear dependent upon locomotor activation by nicotine

A quantitative analysis of the reward-enhancing effects of nicotine using reinforcer demand

Reward enhancement by nicotine has been suggested as an important phenomenon contributing toward tobacco abuse and dependence. Reinforcement value is a multifaceted construct not fully represented by any single measure of response strength. The present study evaluated the changes in the reinforcement value of a visual stimulus in 16 male Sprague–Dawley rats using the reinforcer demand technique proposed by Hursh and Silberberg. The different parameters of the model have been shown to represent differing facets of reinforcement value, including intensity, perseverance, and sensitivity to changes in response cost. Rats lever-pressed for 1-min presentations of a compound visual stimulus over blocks of 10 sessions across a range of response requirements (fixed ratio 1, 2, 4, 8, 14, 22, 32). Nicotine (0.4 mg/kg, base) or saline was administered 5 min before each session. Estimates from the demand model were calculated between nicotine and saline administration conditions within subjects and changes in reinforcement value were assessed as differences in Q0, Pmax, Omax, and essential value. Nicotine administration increased operant responding across the entire range of reinforcement schedules tested, and uniformly affected model parameter estimates in a manner suggesting increased reinforcement value of the visual stimulus

OPERATIONALIZING HUMILITY: A MODEL OF SITUATIONAL HUMILITY FOR CHRISTIAN COLLEGE STUDENT LEADERS

This research study explored how college student leaders operationalize humility in their actions and what leads individuals to act with situational humility. There is a rise in narcissistic tendencies in college students (Twenge, Konrath, Campbell, & Bushman, 2008a, 2008b) and a decline in overall character traits (Burns, 2012; Hunter, 2000; Liddell & Cooper, 2012). Opposite the vice of narcissism sits the virtue of humility (Emmons, 2000; Exline & Geyer, 2004; Peterson & Seligman, 2004; Tangney, 2000). Using a grounded theory approach, the researcher looked to discover the process of humility development. Twenty six in depth interviews were conducted at three institutions. Each institution was a member of the Council of Christian Colleges and Universities and each participant identified as having a Christian belief system. Interviews were digitally recorded and transcribed. Transcriptions were coded using grounded theory method of open, axial, and selective coding. Based on the data collected three main themes emerged. Faith and humility go hand in hand, sense of self impacts humbling experiences, and the effect of relationships on humility. Through this research, the model of situational humility emerged grounded in the data. The model of situational humility describes what leads an individual to act with humility within a specific humbling experience. For these students, humbling experiences occurred when their sense of self (“I am an athlete,” “I get things done on time,” “I am a not racist”) did not line of up with their experience of the world (physical injury, failing to send necessary emails, making comments that were received as racial insensitive by a peer). Individuals then move to iv the point of change where they must decide how whether they will reorient their sense of self or actions or if they will not reorient and act with pride. In this point of change individuals were positively impacted towards humility by their Christian belief system, empathy, being in relationship, and interacting with others who were different from them. The implications of this research for institutional leaders who desire to grow humility in students include valuing how humility is seen as a virtue, growing empathy in students, and providing opportunities for students to be in relationship with others, specifically those who are different from them

Laboratory Notes From Behavioral Pharmacologists and Trainees: Considerations for the Discipline

In several laboratory meetings, we discussed the challenges that face trainees in behavioral pharmacology. Major concerns, such as a difficult funding climate and limited academic job prospects were discussed at first. However, we decided to concentrate on ways to meet these challenges; versus focusing on negatives and listing gripes. Within this more constructive framework, we identified the importance of broadening training to aligned areas to enhance the capacity of behavioral pharmacologists to collaborate in multidisciplinary teams. With increased breadth of training comes the concern for a balance that does not cheat trainees out of the depth of training also needed for success. We believe that behavioral pharmacologists trained in this manner will be ideally positioned to be leaders of these translational research teams. Related to the breadth and depth of training is the recent concerns over replicability and reproducibility of published research. Behavioral pharmacologists, with the rigors of training in behavioral analysis and experimental design, can be at the forefront of this conversation. This will be especially true if current training is reinforced with additional experience in the use of cutting-edge statistical tools that address the complex experimental designs and large data sets that emerge from modern multidisciplinary collaborations. Finally, communicating the import and potential societal impact of our research to legislators, other scientists, educators, school children, neighbors, and acquaintances is needed to ensure that our field thrives. In closing, the process of explicitly discussing the challenges and potential solutions with current trainees will enhance their mentoring and training

Laboratory Notes From Behavioral Pharmacologists and Trainees: Considerations for the Discipline

In several laboratory meetings, we discussed the challenges that face trainees in behavioral pharmacology. Major concerns, such as a difficult funding climate and limited academic job prospects were discussed at first. However, we decided to concentrate on ways to meet these challenges; versus focusing on negatives and listing gripes. Within this more constructive framework, we identified the importance of broadening training to aligned areas to enhance the capacity of behavioral pharmacologists to collaborate in multidisciplinary teams. With increased breadth of training comes the concern for a balance that does not cheat trainees out of the depth of training also needed for success. We believe that behavioral pharmacologists trained in this manner will be ideally positioned to be leaders of these translational research teams. Related to the breadth and depth of training is the recent concerns over replicability and reproducibility of published research. Behavioral pharmacologists, with the rigors of training in behavioral analysis and experimental design, can be at the forefront of this conversation. This will be especially true if current training is reinforced with additional experience in the use of cutting-edge statistical tools that address the complex experimental designs and large data sets that emerge from modern multidisciplinary collaborations. Finally, communicating the import and potential societal impact of our research to legislators, other scientists, educators, school children, neighbors, and acquaintances is needed to ensure that our field thrives. In closing, the process of explicitly discussing the challenges and potential solutions with current trainees will enhance their mentoring and training

Examining the Reinforcement-Enhancement Effects of Phencyclidine and Its Interactions with Nicotine on Lever-Pressing for a Visual Stimulus

Nicotine is a widely-abused drug, yet its primary reinforcing effect does not seem potent as other stimulants such as cocaine. Recent research on the contributing factors toward chronic use of nicotine-containing products has implicated the role of reinforcement-enhancing effects of nicotine. The present study investigates whether phencyclidine (PCP) may also possess a reinforcement-enhancement effect and how this may interact with the reinforcement-enhancement effect of nicotine. PCP was tested for two reasons: 1) it produces discrepant results on overall reward, similar to that seen with nicotine and 2) it may elucidate how other compounds may interact with the reinforcement-enhancement of nicotine. Adult male Sprague-Dawley rats were trained to lever press for brief visual stimulus presentations under fixed-ratio (FR) schedules of reinforcement and then were tested with nicotine (0.2 or 0.4 mg/kg) and/or PCP (2.0 mg/kg) over six increasing FR values. A selective increase in active lever-pressing for the visual stimulus with drug treatment was considered evidence of a reinforcement-enhancement effect. PCP and nicotine separately increased active lever pressing for a visual stimulus in a dose-dependent manner and across the different FR schedules. The addition of PCP to nicotine did not increase lever-pressing for the visual stimulus, possibly due to a ceiling effect. The effect of PCP may be driven largely by its locomotor stimulant effects, whereas the effect of nicotine was independent of locomotor stimulation. This dissociation emphasizes that distinct pharmacological properties contribute to the reinforcement-enhancement effects of substances

Examining the Reinforcement-Enhancement Effects of Phencyclidine and Its Interactions with Nicotine on Lever-Pressing for a Visual Stimulus

Nicotine is a widely-abused drug, yet its primary reinforcing effect does not seem potent as other stimulants such as cocaine. Recent research on the contributing factors toward chronic use of nicotine-containing products has implicated the role of reinforcement-enhancing effects of nicotine. The present study investigates whether phencyclidine (PCP) may also possess a reinforcement-enhancement effect and how this may interact with the reinforcement-enhancement effect of nicotine. PCP was tested for two reasons: 1) it produces discrepant results on overall reward, similar to that seen with nicotine and 2) it may elucidate how other compounds may interact with the reinforcement-enhancement of nicotine. Adult male Sprague-Dawley rats were trained to lever press for brief visual stimulus presentations under fixed-ratio (FR) schedules of reinforcement and then were tested with nicotine (0.2 or 0.4 mg/kg) and/or PCP (2.0 mg/kg) over six increasing FR values. A selective increase in active lever-pressing for the visual stimulus with drug treatment was considered evidence of a reinforcement-enhancement effect. PCP and nicotine separately increased active lever pressing for a visual stimulus in a dose-dependent manner and across the different FR schedules. The addition of PCP to nicotine did not increase lever-pressing for the visual stimulus, possibly due to a ceiling effect. The effect of PCP may be driven largely by its locomotor stimulant effects, whereas the effect of nicotine was independent of locomotor stimulation. This dissociation emphasizes that distinct pharmacological properties contribute to the reinforcement-enhancement effects of substances

The Naas Motorway Bypass - A Cost Benefit Analysis. Quarterly Economic Commentary Special Article, January 1984

The paper examines the Naas Motorway Bypass which cost £16m at 1983 prices. Twelve thousand vehicles a day using the bypass save over 10 minutes between 8 am and 8 pm and 6 minutes at other times. Five thousand vehicles a day using the present route through Naas also benefit by saving 4 minutes due to reduced congestion in the town. In addition to time savings, the bypass reduces accidents and fuel costs. Ninety-one per cent of the benefits accrue in time savings. The internal rate of return on the project is estimated at 20.51 per cent, assuming 2 per cent annual traffic and income growth. The sensitivity tests of the results show that even with zero growth in incomes and traffic for twenty years, a high proportion of leisure time savings with zero value and no increase in the value of fuel savings the project would have an internal rate of return which meets the test discount rate used by the Department of Finance. The environmental aspects of the bypass are positive in terms of noise and smoke and lead pollution reduction. The impact on farm severence and natural amenities on the motorway route has been mitigated by several design features of the bypass