Probability Discounting of Lewis and Fischer 344 rats: Strain Comparisons at Baseline and Following Acute Administration of d-Amphetamine

Risky choice can be defined as choice for a larger, uncertain reinforcer over a smaller, certain reinforcer when choosing the smaller alternative maximizes reinforcement. Risky choice is studied using various procedures in the animal laboratory; one such procedure is called probability discounting. There are many variables that contribute to risky decision-making, including biological and pharmacological determinants. The present study assessed both of these variables by evaluating dose-response effects of d-amphetamine on risky choice of Lewis (LEW) and Fischer 344 (F344) rats. The probability-discounting procedure included discrete-trials choices between one food pellet delivered 100% of the time and three food pellets delivered following one of varying probabilities. The probability of three food pellets being delivered decreased systematically across blocks within each session. At baseline, risky choice did not differ between LEW and F344. However, choice for LEW became significantly less risky throughout extended training while choice for F344 remained relatively stable over time. d-Amphetamine significantly increased risky choice for both rat strains at low-to-moderate doses (0.1 and 0.3 mg/kg), although it did so at a lower dose for F344 (0.1 and 0.3 mg/kg) than LEW (0.3 mg/kg only), suggesting greater behavioral sensitivity to effects of d-amphetamine for F344. High doses of d-amphetamine (1.0 and 1.8 mg/kg) produced overall disruptions in choice for both strains, indicated by reductions in choice for the larger, uncertain alternative when the probability of delivery was relatively high and increases when the probability was relatively low. Results from the current study stand in contrast to previous reports investigating impulsive choice (i.e., choice involving temporal delays rather than uncertainty) of LEW and F344. Thus, the present work underscores the importance of considering risky and impulsive choice as two separate, but related, behavioral processes

Will d-amphetamine’s effect on impulsive choice be consistent when the environmental context changes by using decreasing delays to reinforcement?

Impulsivity (choosing a smaller, more immediate reward over a larger, more delayed reward) and substance abuse are positively correlated. It is important to understand how factors like delay to reward and drug effects determine impulsive choice, which can be studied using animal models. This study evaluated impulsive choice in rats, where delays to the larger reward (three food pellets) were presented in decreasing order versus one food pellet delivered immediately. Then, effects of d-amphetamine were assessed. It was found that in three of four rats, d-amphetamine increased impulsive choice when the larger option was presented with decreasing delays. This effect is contrary to what has generally been found with increasing delays. Thus, environmental context can influence drug effects on impulsive choice

Executive (dys)function after stroke: special considerations for behavioral pharmacology

Stroke is a world-wide leading cause of death and long-term disability with concurrent secondary consequences that are largely comprised of mood dysfunction, as well as sensory, motor, and cognitive deficits. This review focuses on the cognitive deficits associated with stroke specific to executive dysfunction (including decision making, working memory, and cognitive flexibility) in humans, non-human primates, and additional animal models. Further, we review some of the cellular and molecular underpinnings of the individual components of executive dysfunction and their neuroanatomical substrates after stroke, with an emphasis on the changes that occur during biogenic monoamine neurotransmission. We concentrate primarily on changes in the catecholaminergic (dopaminergic and noradrenergic) and serotonergic systems at the levels of neurotransmitter synthesis, distribution, re-uptake, and degradation. We also discuss potential secondary stroke-related behavioral deficits (specifically, post-stroke depression as well as drug-abuse potential and addiction) and their relationship with stroke-induced deficits in executive function, an especially important consideration given that the average age of the human stroke population is decreasing. In the final sections, we address pharmacological considerations for the treatment of ischemia and the subsequent functional impairment, as well as current limitations in the field of stroke and executive function research

Executive (dys)function after traumatic brain injury: special considerations for behavioral pharmacology

Executive function is an umbrella term that includes cognitive processes such as decision-making, impulse control, attention, behavioral flexibility, and working memory. Each of these processes depends largely upon monoaminergic (dopaminergic, serotonergic, and noradrenergic) neurotransmission in the frontal cortex, striatum, and hippocampus, among other brain areas. Traumatic brain injury (TBI) induces disruptions in monoaminergic signaling along several steps in the neurotransmission process – synthesis, distribution, and breakdown – and in turn, produces long-lasting deficits in several executive function domains. Understanding how TBI alters monoamingeric neurotransmission and executive function will advance basic knowledge of the underlying principles that govern executive function and potentially further treatment of cognitive deficits following such injury. In this review, we examine the influence of TBI on the following measures of executive function – impulsivity, behavioral flexibility, and working memory. We also describe monoaminergic-systems changes following TBI. Given that TBI patients experience alterations in monoaminergic signaling following injury, they may represent a unique population with regard to pharmacotherapy. We conclude this review by discussing some considerations for pharmacotherapy in the field of TBI

Effects of Housing Condition and Acute Nicotine on Impulsive Choice in Lewis and Fischer 344 Rats

Impulsive choice is defined as choice for a smaller, more immediate reinforcer relative to a larger, delayed reinforcer, and is commonly studied using delay-discounting procedures. There are many variables that contribute to impulsive choice, including biological and environmental determinants. The present study examined both of these variables by evaluating effects of housing condition (single versus paired) on impulsive choice in Lewis (LEW) and Fischer 344 (F344) rats, at baseline and following acute nicotine administration. A within-session procedure was used in which choice was between one food pellet delivered immediately and three food pellets delivered after a delay. The delay to three food pellets was increased systematically across blocks within a session and indifference points were calculated. Paired housing significantly reduced impulsive choice for both rat strains relative to single housing (archival data). In addition, when singly housed, choice was more impulsive for LEW rats relative to F344 rats at baseline. When pair housed, this strain difference was attenuated. Following acute nicotine administration, impulsive choice was significantly reduced at 0.3 mg/kg for singly housed LEW rats and 1.0 mg/kg for singly housed F344 rats. However, when pair housed, 0.3 and 1.0 mg/kg both reduced impulsive choice regardless of rat strain. Thus, previously reported effects of environmental enrichment (i.e., reduced impulsive choice) seem to be, as least in part, due to social housing. It also appears as though effects of nicotine on impulsive choice are baseline-dependent and paired housing may make impulsive choice in F344 rats more sensitive to effects of nicotine

Device features and user behaviors as predictors of dependence among never-smoking electronic cigarette users: PATH Wave 4

Introduction: Electronic cigarettes (ECIGs) vary greatly in their ability to deliver nicotine, which suggests they may also vary in their ability to produce dependence. This study examined individual and combined ECIG device features, and also user behaviors, as predictors of dependence in never-smoking ECIG users. Methods Data were collected from 711 current ECIG users who had smoked \u3c100 cigarettes in their lifetime at Wave 4 of the Population Assessment of Tobacco and Health (PATH) Study. Multivariable linear regressions examined individual (e.g., contains nicotine, uses a tank, flavor preference) and combined (e.g., refillable tanks, refillable mods) device features, and user behaviors (e.g., uses/day) as predictors of dependence, withdrawal, and craving after accounting for demographic variables. Results Results for ECIG dependence and craving showed a similar pattern; higher levels were observed for older age, more frequent past 30-day use, using an ECIG containing nicotine (vs no nicotine), and using a non-refillable cartridge or refillable tank style (vs disposables). Higher withdrawal levels were observed for higher education levels and individual device features of tank (vs no tank), cartridge (vs no cartridge), refillable (vs non-refillable), and “other” flavor preference (vs tobacco flavor). Lower withdrawal levels were associated with a preference for sweet/fruit flavor(s) (vs tobacco flavor). Conclusions Few use behaviors and device features, whether examined alone or in combination, predicted dependence-related outcomes. Findings underscore the challenge with regulating ECIG products in the current marketplace, which is inundated with a myriad of device types

Geographic isolation predicts tobacco product use among youth: A latent class analysis

PURPOSE: The purpose of the current study was to evaluate associations between geographic rurality and tobacco use patterns among adolescents. METHODS: High school students (N = 566) from north-central Appalachia reported on their lifetime and/or current use of cigarettes, electronic cigarettes (ECIGs), cigars, and smokeless tobacco. Geographic rurality was measured via the Isolation scale, whereby residential ZIP Codes determined the degree to which respondents have access to health-related resources. Latent class analysis (LCA) was used to identify discrete classes of adolescent tobacco users based on their use of tobacco products. Then, associations between participants\u27 geographic rurality and class membership were evaluated using a series of multinomial logistic regressions. FINDINGS: LCA classified participants as Nonusers, Current ECIG Users, Cigarette/ECIG Experimenters, and Polytobacco Users. Individuals with higher Isolation scores were more likely to be Polytobacco Users and Cigarette/ECIG Experimenters than Nonusers, and were more likely to be Polytobacco Users than Current ECIG Users. CONCLUSIONS: The continuous Isolation scale used in the present study predicted polytobacco use patterns among adolescents in a manner that is consistent with, while simultaneously expanding upon, prior work. Tobacco control practices and policies should be viewed through a lens that considers the unique needs of geographically isolated areas

Global polity in adult education and UNESCO: landmarking, brokering and framing policy

Aknowledging the complexity of local\u2013global interconnections, the author argues for the adoption of a global polity perspective in adult education, here applied to study mobilisation processes that occur through UNESCO. The findings point to three processes that cross geopolitical borders and professional interests: \u2018landmarking\u2019, by which a shared sense of a common past is created; \u2018brokering\u2019, which helps shape a common future direction; and \u2018framing\u2019, which is used to convert ideational landscapes into material government-led actions. The theoretical perspectives and analytical insights presented could be used in analogous studies in other areas of education or with a focus on different political actors