Differential phase-amplitude coupling in nucleus accumbens and orbitofrontal cortex reflects decision-making during a delay discounting task.

BACKGROUND: The impulsive choice is characterized by the preference for a small immediate reward over a bigger delayed one. The mechanisms underlying impulsive choices are linked to the activity in the Nucleus Accumbens (NAc), the orbitofrontal cortex (OFC), and the dorsolateral striatum (DLS). While the study of functional connectivity between brain areas has been key to understanding a variety of cognitive processes, it remains unclear whether functional connectivity differentiates impulsive-control decisions. METHODS: To study the functional connectivity both between and within NAc, OFC, and DLS during a delay discounting task, we concurrently recorded local field potential in NAc, OFC, and DLS in rats. We then quantified the degree of phase-amplitude coupling (PAC), coherence, and Granger Causality between oscillatory activities in animals exhibiting either a high (HI) or low (LI) tendency for impulsive choices. RESULTS: Our results showed a differential pattern of PAC during decision-making in OFC and NAc, but not in DLS. While theta-gamma PAC in OFC was associated with self-control decisions, a higher delta-gamma PAC in both OFC and NAc biased decisions toward impulsive choices in both HI and LI groups. Furthermore, during the reward event, Granger Causality analysis indicated a stronger NAc➔OFC gamma contribution in the HI group, while the LI group showed a higher OFC➔NAc gamma contribution. CONCLUSIONS: The overactivity in NAc during reward in the HI group suggests that exacerbated contribution of NAcCore can lead to an overvaluation of reward that biases the behavior toward the impulsive choice.

To produce or not to produce? Contrasting the effect of substance abuse in social decision-making situations.

Substance use disorders (SUD) have been related to high criminal justice costs, expensive healthcare, social impairment, and decision-making deficits. In non-social decision-making tasks, people with SUD tend to take more risks and choose small immediate rewards than controls. However, few studies have explored how people with SUD behave in social decision-making situations where the resources and profits depend directly on participants' real-time interaction, i.e., social foraging situations. To fulfill this gap, we developed a real-time interaction task to (a) compare the proportion of producers (individuals who tend to search for food sources) and scroungers (individuals who tend to steal or join previously discovered food sources) among participants with SUD and controls with respect to the optimal behavior predicted by the Rate Maximization Model, and (b) explore the relationship between social foraging strategies, prosocial behavior, and impulsivity. Here participants with SUD (n = 20) and a non-user control group (n = 20) were exposed to the Guaymas Foraging task (GFT), the Social Discounting task (SD), and the Delay Discounting task (DD). We found that participants in the control group tended to produce more and obtain higher profits in contrast to substance abuser groups. Additionally, SD and DD rates were higher for scroungers than producers regardless of the group. Our results suggest that producers tend to be more altruistic and less impulsive than scroungers. Knowing more about social strategies and producers' characteristics could help develop substance abuse prevention programs.

Descuento sexual y conductas sexuales arriesgadas en una muestra de adultos jóvenes de Colombia / Sexual Discounting and Sexual Risk Behavior in a Sample of Young Adults from Colombia / Desconto sexual e comportamento sexual de risco em uma amostra de jovens adultos da Colômbia

El objetivo del presente trabajo fue describir la tasa de descuento sexual y evaluar la relación entre el autorreporte de conductas sexuales arriesgadas (csa) y el descuento sexual en una muestra de adultos jóvenes en Colombia. Para esto, se realizó una investigación no experimental de corte transversal y correlacional. Ciento treinta y seis participantes fueron sometidos a un cuestionario de autorreporte de conductas de riesgo sexual, a la tarea de descuento sexual (sddt) y al cuestionario de elección monetaria (mcq). Los análisis de la curva de descuento sexual demuestran que el valor de la opción de tener sexo seguro disminuye con el in-cremento en la demora en la obtención de un condón (i. e., descuento sexual). Adicionalmente, se observa que el grado de descuento sexual está asociado con csa, como el número de parejas sexuales y el número de relaciones sexuales en los últimos tres meses, y que hay una diferencia en el patrón de descuento sexual entre hombres y mujeres.

The goal of this study was to describe the rate of sexual discounting and its relation with the self-report of sexual risk behavior in a sample of young adults from Colombia. To achieve this goal, a correlational cross-sectional non-experimental study was done. One hundred thirty six young adult participants responded to a sexual risk behavior self-report questionnaire, a sexual delay discounting task (sddt), and a monetary choice questionnaire (mcq). The results suggest that the value of the safe sex option decreases with the delay to obtain a condom (i. e., sexual discounting). Additionally, it was observed that the sexual discounting rate was associated with the self-report of sexual risk behavior, like, the number of sexual partners and sexual encounters in the last three months. It was also observed a different pattern of sexual discounting between men and women

O objetivo deste estudo foi descrever a taxa de desconto sexual e avaliar a relação entre o autorrelato de com-portamentos sexuais de risco (csr) e o desconto sexual em uma amostra de jovens adultos na Colômbia. Para isso, foi realizada uma investigação não experimental, transversal e correlacional. 136 participantes foram submetidos a um questionário de comportamentos se-xuais de risco autorreferidos, à tarefa de desconto sexual (sddt) e ao questionário de escolha monetária (mcq). As análises da curva de desconto sexual mostram que o valor da opção de praticar sexo mais seguro diminui com o aumento do atraso na obtenção do preservativo (ou seja, desconto sexual). Adicionalmente, observa-se que o grau de desconto sexual está associado à csr, assim como o número de parceiros sexuais e o número de relações sexuais nos últimos 3 meses, e que existe uma diferença no padrão de desconto sexual entre homens e mulheres.

Cultural differences in intertemporal decision making: A comparison between Chile and China.

A cross-cultural comparison is made of delay discounting in samples of participants from Chile and China. Comparisons are made based on previous literature that suggests that individuals from an Asian culture should be willing to postpone delayed rewards more than are individuals from a Latin American culture. To test the cross-cultural validity of a hyperbolic discounting model, the model was fitted to both data sets. Additionally, a self-enhancement measure was evaluated as a potential mediator between culture of origin and delay discounting. Seventy-eight college students from China and 120 college students from Chile, with similar demographic backgrounds, discounted hypothetical monetary outcomes using an adjusting-amount titration procedure. Additionally, participants completed a self-enhancement measure. Age, academic major, gender, and grade point average were controlled. Chilean participants discounted much more steeply than Chinese nationals did. No support was obtained for the mediation of self-enhancement between culture of origin and degree of delay discounting. In both samples, delay discounting was better described by a hyperboloid than an exponential function, the only exception being the $10,000 condition in which the medians for Chilean participants' present subjective value were equally well explained by a hyperboloid and an exponential function.

Moderate Stability among Delay, Probability, and Effort Discounting in Humans.

The stability of delay discounting across time has been well-established. However, limited research has examined the stability of probability discounting, and no studies of the stability of effort discounting are available. The present study assessed the steady-state characteristics of delay, probability, and effort discounting tasks across time with hypothetical rewards in humans, as well as whether response characteristics suggested a common discounting equation. Participants completed delay, probability, and effort discounting tasks on three occasions. We found moderate relative stability of delay and probability tasks, and similar evidence for absolute stability across time for all tasks. The interclass correlations coefficient showed some correspondence across time points and tasks, and higher levels of between subject variability, especially for the effort discounting task, suggesting trait level variables has a stronger influence on performance than state level variables. Performance on the delay and probability tasks were moderately correlated and similar mathematical functions fit choice patterns on both tasks (hyperbolic), suggesting that delay and probability discounting processes shared some common elements. Lower correlations and different function fits suggested that effort discounting involves more unique features.

Chronic early-life stress increases cognitive impulsivity and D2 immunoreactivity in the nucleus accumbens of adult rats.

Chronic early life stress (ECS) induced by limited bedding and nesting (LBN) material in rodents is a naturalistic stress model that mimics many of the behavioral and neural consequences of child abuse and neglect; however, the effect of ECS on adult impulsivity has never been studied. The aim of our work was to determine the effects of ECS on cognitive impulsivity and its relation to D2 immunoreactivity in the nucleus accumbens (NAc) and prefrontal cortex (PFC) of adult male rats. Sprague-Dawley rats were exposed to LBN from postnatal day 2 to 9. We evaluated dams' maternal behavior and offspring corticosterone levels. The rats' impulsive cognitive behavior was evaluated by a delay-discounting task (transitional bridge) on P70, and we evaluated D2 receptors by immunostaining. Our results indicated that ECS affected maternal behavior in the dams and increased pups' corticosterone levels at P9, but not in adults. ECS rats showed lower frequencies of choosing the delayed reinforcer and shorter latencies to cross on the delay-discounting task. In addition, ECS rats showed increased D2 immunoreactivity in the NAc when compared with controls. Our data suggest that ECS can cause impulsive behaviors in adult rats characterized by less convenient choices, likely related to an increase in D2 receptors in the NAc. These findings could contribute to our understanding of the effects of child abuse and neglect on impulsive behavior.

High impulsive choice is accompanied by an increase in dopamine release in rat dorsolateral striatum.

Dopamine neurotransmission has been consistently associated with individual differences in impulsive choice. Clinical and preclinical evidence suggests that low striatal dopamine D2 signaling predisposes to engage in impulsive behaviors. Although dopamine D2 signaling controls dopamine (DA) extracellular levels, the relationship between striatal dopamine extracellular levels and impulsive choice remains poorly understood. Using quantitative microdialysis, we investigated whether extracellular DA levels in rat dorsolateral striatum (DLS) correlates with preference for an immediate small reward or for a delayed larger reward. Rats were tested in a delay-discounting task and classified as high impulsive (HI) or low impulsive (LI) according to the area under the discounting curve (AUC). No-net flux microdialysis experiments, assessing basal DA release, DA-uptake, and DA extracellular concentration (DA Cext), were carried out in dorsolateral striatum (DLS) of urethane-anesthetized rats. Rats classified as HI showed a higher DA release compared with LI rats. Differences in DLS DA-uptake and DA Cext were non-significant. Importantly, a significant negative correlation was observed between AUC and DA release, indicating that the lower the AUC, the higher the DLS DA release. This finding shows that DA release is augmented in the DLS of rats classified as HI, suggesting that a hyper-activated nigro-striatal pathway contributes to impulsive choice.

Inventário de Adiamento de Gratificação (DGI-35): propriedades psicométricas da versão brasileira / The 35-Item Delaying Gratification Inventory (DGI-35): psychometric properties of the Brazilian version / Inventario de Aplazamiento de Bonificación (DGI-35): propiedades psicométricas de la versión brasileña

O Inventário de Adiamento de Gratificação (DGI-35) foi desenvolvido para avaliar os diferentes níveis de adiamento de gratificação presentes na população geral. O objetivo deste estudo foi apresentar as propriedades psicométricas do DGI-35 para a população brasileira e evidências de validade convergente com a Escala de Impulsividade de Barratt (BIS-11). Participaram 405 brasileiros (61,2% mulheres), com idades entre 18 e 46 anos (M = 22,32, DP = 4,78). Foram conduzidas análises fatoriais exploratórias e confirmatórias com vistas a avaliar a estrutura interna do instrumento. Dos cinco fatores originais, quatro tiveram estrutura interna semelhante à versão original, exceto o fator "Físico" que não se ajustou ao modelo, levando a criação de uma alternativa de 28 itens à escala original (DGI-28), que apresentou adequados índices de ajuste. Conforme esperado, o escore global da DGI-28, bem como os seus fatores estiveram negativamente relacionados ao escore global da BIS-11. (AU)

The Delaying Gratification Inventory (DGI-35) was developed to evaluate different levels of gratification delaying in the general population. The purpose of this study was to present the psychometrics properties of the DGI-35 in the Brazilian population and evidence of convergent validity with the Barrat Impulsivity Scale (BIS-11). A total of 405 participants were selected (61.2% women) aged between 18 and 46 years (M = 22.32, SD = 4.78). Exploratory and confirmatory factor analyses were conducted to evaluate the internal structure of the instrument. Four out of five original factors showed identical consistency, except for the "Physical" factor that did not fit the model, leading to the creation of an alternative of 28 items to the original scale (DGI-28), which presented good fit indices. As expected, the global score of the DGI-28, as well as its factors were negatively correlated to the global score of the BIS-11. (AU)

El Inventario de Aplazamiento de Bonificación (DGI-35) fue desarrollado para evaluar los diferentes niveles de prórrogas de bonificación presentes en la población general. El objetivo de este estudio fue presentar las propiedades psicométricas del DGI-35 para la población brasileña y evidencias de validez convergentes con la Escala de Impulsividad de Barratt (BIS-11). Participaron 405 brasileños (61,2% mujeres) con edades entre 18 y 46 años (M = 22,32, DE = 4,78). Fueron realizados análisis factorial confirmatoria y exploratorio que evaluaron la estructura interna del instrumento. De los cinco factores originales, cuatro tuvieron estructura interna semejante a la versión original, excepto el factor "Físico" que no se ajustó al modelo, creándose una alternativa de 28 ítems (DGI-28) a la escala original, la cual presentó índices de ajuste adecuados. Como se esperaba, la puntuación global de la DGI-28, así como sus factores estuvieron negativamente relacionados con la puntuación global de la BIS-11. (AU)

Disinhibition in Frontotemporal Dementia and Alzheimer's Disease: A Neuropsychological and Behavioural Investigation.

OBJECTIVE: Cognitive tests of inhibitory control show variable results for the differential diagnosis between behavioural variant of Frontotemporal Dementia (bvFTD) and Alzheimer's disease (AD). We compared the diagnostic accuracies of tests of inhibitory control and of a behavioural questionnaire, to distinguish bvFTD from AD. METHODS: Three groups of participants were enrolled: 27 bvFTD patients, 25 AD patients, and 24 healthy controls. Groups were matched for gender, education, and socio-economic level. Participants underwent a comprehensive neuropsychological assessment of inhibitory control, including Hayling Test, Stroop, the Five Digits Test (FDT) and the Delay Discounting Task (DDT). Caregivers completed the Barratt Impulsiveness Scale 11th version (BIS-11). RESULTS: bvFTD and AD groups showed no difference in the tasks of inhibitory control, while the caregiver questionnaire revealed that bvFTD patients were significantly more impulsive (BIS-11: bvFTD 76.1+9.5, AD 62.9+13, p < .001). CONCLUSIONS: Neuropsychological tests of inhibitory control failed to distinguish bvFTD from AD. On the contrary, impulsivity caregiver-completed questionnaire provided good distinction between bvFTD and AD. These results highlight the current limits of cognitive measures of inhibitory control for the differential diagnosis between bvFTD and AD, whereas questionnaire information appears more reliable and in line with clinical diagnostics.

Toward a Unifying Account of Impulsivity and the Development of Self-Control.

Impulsivity has traditionally been thought to involve various behavioral traits that can be measured using different laboratory protocols. Whereas some authors regard different measures of impulsivity as reflecting fundamentally distinct and unrelated behavioral tendencies (fragmentation approach), others regard those different indexes as analogue forms of the same behavioral tendency, only superficially different (unification approach). Unifying accounts range from mere intuitions to more sophisticated theoretical systems. Some of the more complete attempts at unifying are intriguing but have validity weaknesses. We propose a new unifying attempt based on theoretical points posed by other authors and supplemented by theory and research on associative learning. We then apply these assumptions to characterize the paradigms used to study impulsivity in laboratory settings and evaluate their scope as an attempt at unification. We argue that our approach possesses a good balance of parsimony and empirical and theoretical grounding, as well as a more encompassing scope, and is more suitable for experimental testing than previous theoretical frameworks. In addition, the proposed approach is capable of generating a new definition of impulsivity and outlines a hypothesis of how self-control can be developed. Finally, we examine the fragmentation approach from a different perspective, emphasizing the importance of finding similarities among seemingly different phenomena.

Relación de las creencias mágicas con el descuento de recompensas monetarias / Relation of magical beliefs with discounting of monetary rewards

Resumen Se ha sugerido que las creencias mágicas, religiosas y supersticiosas, están relacionadas con las conductas de autocontrol/ impulsividad y de aversión/propensión al riesgo. Estas conductas pueden cuantificarse con la métrica del descuento del valor de una recompensa en función de su demora de entrega o probabilidad de ocurrencia. Así, el propósito del presente trabajo fue averiguar la relación entre las creencias mágicas y el autocontrol/impulsividad y la aversión/propensión al riesgo, utilizando el método del descuento del valor relativo de las recompensas. Ochenta participantes respondieron tres tareas; una de creencias mágicas, otra de descuento temporal y una de descuento probabilístico. El resultado principal del estudio fue que los participantes que mostraron un mayor índice de credulidad en creencias religiosas y supersticiosas mostraron una mayor tasa de descuento temporal y probabilístico que los participantes que tuvieron índices más bajos de credulidad en las mismas creencias. Estos resultados sugieren una relación entre las creencias mágicas y los fenómenos estudiados con la métrica del descuento del valor relativo de recompensas demoradas o probables. Esto es, los datos sugieren que los participantes con un nivel más alto de creencias mágicas también mostraron más conductas impulsivas y de aversión al riesgo que los participantes con niveles más bajos de creencias.

Abstract It has been suggested that magical beliefs like religious and superstitious ones are related with self-controlled/impulsive and risk aversion/proneness behaviors that people show. These behaviors could be quantified with discounting of the value of a reward as a function of its delay of delivery or probability of occurrence, respectively. Therefore, the purpose of this work was to investigate the relationship between magical beliefs and self-controlled/impulsive and risk-aversion/proneness behaviors using the method of discounting the relative value of the rewards. Eighty participants answered three tasks that were a magical beliefs one, a delay discounting one and a probability discounting one. The main finding of the study was that participants who had a higher score in the religious and the superstitious beliefs also had higher discount rates on temporal and probability discounting tasks than the ones who had a lower score in the magical beliefs. These results suggest a relation between magical beliefs and the phenomena studied with the discounting of the subjective value of delayed or probabilistic rewards. That is, these data suggest that the participants who showed a higher level of magical beliefs also showed more impulsive and risk-averse behaviors than the participants who showed lower level of beliefs.

Delay discounting: concepts and measures

Delay discounting, one element which underlies decision-making, can be defined as the depreciation of the value of a reward related to the time that it takes to be released. High rates of delay discounting are found in subjects who are willing to forgo greater rewards available only after some length of time and who show a preference for smaller rewards that are available immediately. Widely used as a measure of impulsiveness, delay discounting can be evaluated using experimental tasks. The present review evaluated tasks of delay discounting, their features, measures of evaluation and anomalies, and some variables that can affect delay discounting results and applications in the study of individual and intra-individual differences.

Delay discounting: concepts and measures

Delay discounting, one element which underlies decision-making, can be defined as the depreciation of the value of a reward related to the time that it takes to be released. High rates of delay discounting are found in subjects who are willing to forgo greater rewards available only after some length of time and who show a preference for smaller rewards that are available immediately. Widely used as a measure of impulsiveness, delay discounting can be evaluated using experimental tasks. The present review evaluated tasks of delay discounting, their features, measures of evaluation and anomalies, and some variables that can affect delay discounting results and applications in the study of individual and intra-individual differences.(AU)

Prenatal alcohol exposure did not affect impulsivity in rats that performed delay or probability discounting tasks

Individuals who fall under the spectrum of the Fetal Alcohol Syndrome have a higher prevalence of several cognitive disturbances, including a greater probability of being diagnosed with attention-deficit hyperactivity disorder (ADHD). Some of these effects, such as hyperactivity and attentional impairments, are already well established in the literature. The assessment of impulsive choice, however, has received little attention in human and animal studies. In the present study, we attempted to investigate the effects of prenatal ethanol exposure on two tasks related to impulsive choice that have never been studied in this condition: delay and probability discounting. METHOD: Rats prenatally exposed to ethanol (liquid diets with 0 percent, 10 percent, or 35 percent ethanol-derived calories [EDC] or laboratory chow) were trained to respond for food in either delay (n = 21) or probability (n = 48) discounting tasks performed in computer-controlled operant conditioning chambers. RESULTS: Prenatal treatment failed to differentiate the rates at which the rats chose the larger reinforcer associated with delay - in a task in which 35 percent EDC was not tested - or risk, although the results suggest that further tests are warranted.

Prenatal alcohol exposure did not affect impulsivity in rats that performed delay or probability discounting tasks

Individuals who fall under the spectrum of the Fetal Alcohol Syndrome have a higher prevalence of several cognitive disturbances, including a greater probability of being diagnosed with attention-deficit hyperactivity disorder (ADHD). Some of these effects, such as hyperactivity and attentional impairments, are already well established in the literature. The assessment of impulsive choice, however, has received little attention in human and animal studies. In the present study, we attempted to investigate the effects of prenatal ethanol exposure on two tasks related to impulsive choice that have never been studied in this condition: delay and probability discounting. METHOD: Rats prenatally exposed to ethanol (liquid diets with 0 percent, 10 percent, or 35 percent ethanol-derived calories [EDC] or laboratory chow) were trained to respond for food in either delay (n = 21) or probability (n = 48) discounting tasks performed in computer-controlled operant conditioning chambers. RESULTS: Prenatal treatment failed to differentiate the rates at which the rats chose the larger reinforcer associated with delay - in a task in which 35 percent EDC was not tested - or risk, although the results suggest that further tests are warranted.(AU)