The IntelliCage System: A Review of Its Utility as a Novel Behavioral Platform for a Rodent Model of Substance Use Disorder

The use of animal models for substance use disorder (SUD) has made an important contribution in the investigation of the behavioral and molecular mechanisms underlying substance abuse and addiction. Here, we review a novel and comprehensive behavioral platform to characterize addiction-like traits in rodents using a fully automated learning system, the IntelliCage. This system simultaneously captures the basic behavioral navigation, reward preference, and aversion, as well as the multi-dimensional complex behaviors and cognitive functions of group-housed rodents. It can reliably capture and track locomotor and cognitive pattern alterations associated with the development of substance addiction. Thus, the IntelliCage learning system offers a potentially efficient, flexible, and sensitive tool for the high-throughput screening of the rodent SUD model.

Economic choice between remifentanil and food in squirrel monkeys

Traditional approaches for evaluating if compounds are reinforcing, and thus a risk for abuse, include preclinical self-administration procedures conducted in the absence of alternative reinforcers. While the track record of this approach for determining abuse potential is good, that for predicting efficacy of addiction treatments is not. An alternate approach would be economic choice between drug and nondrug rewards, with parametrically varied options from trial to trial. This would promote goal-directed decisions between reward modalities and should provide metrics that reflect changes in internal state that influence desirability of a given option. We report herein a high throughput economic choice procedure in which squirrel monkeys choose between a short-lived opiate, remifentanil, and a palatable food reward. Stimuli on touchscreens indicate the amount of each reward type offered by varying the number of reward-specific elements. The rapid clearance of remifentanil avoids accumulation of confounding levels of drug, and permits a large number of trials with a wide range of offers of each reward modality. The use of a single metric encompassing multiple values of each reward type within a session enables estimation of indifference values using logistic regression. This indifference value is sensitive to reward devaluation within each reward domain, and is therefore a useful metric for determining shifts in reward preference, as shown with satiation and pharmacological treatment approaches.

Enhanced preference for delayed rewards requires the basolateral amygdala and retrosplenial cortex

Abstract‘Sunk’ or irrecoverable costs impact reward-based decisions across species. However, it is not known if these sunk costs elicit a sustained change in reward value. To address this, we developed behavioral task to examine how sunk temporal costs alter reward value and reward preference in rats. We first identified the relative preference between different flavored food pellets during a free-feeding test. Animals were then trained to experience the initial less preferred reward after long delays (high temporal cost) and the initial preferred reward after short delays (low temporal cost). This training regimen enhanced the consumption and preference for the initial less desirable food reward. We probed whether this change in preference required neural systems involved with reward valuation. Pharmacological manipulations and site-specific lesions were performed to examine the potential involvement of the dopamine system, the orbitofrontal cortex (OFC), the basolateral amygdala (BLA), and the retrosplenial cortex (RSC). The change in reward preference was unaffected by systemic dopamine receptor antagonism or OFC lesions. In contrast, lesions of the BLA or the RSC prevented the enhanced consumption and preference for the initial less desirable reward. These findings demonstrate that both the BLA and RSC participate in how sunk temporal costs alter reward value and reward preference.Significance StatementFrom an economic standpoint, only future costs should factor into one’s decisions. However, behavioral evidence across species illustrates that past costs can alter decisions. The goal of this study was to identify the neural systems responsible for past costs influencing subsequent actions. We demonstrate that delivering an initially less desirable reward after long delays (high temporal cost) subsequently increases the consumption and preference for that reward. Furthermore, we identified the basolateral amygdala and the retrosplenial cortex as essential nuclei for mediating this change in reward preference elicited by past temporal costs.

Changes in subjective preference do not require dopamine signaling or the orbital frontal cortex

Abstract‘Sunk’ or unrecoverable costs impact proximal reward-based decisions across species. However, it is not known if these incurred costs elicit a long-lasting change in reward value. To address this, we identified the relative preference between different flavored food pellets in rats. Animals were then trained to experience the initially preferred reward after short delays and the initially less preferred reward after long delays. This training regimen enhanced the preference for the initially less desirable food reward. We probed whether this change in subjective preference involved dopamine signaling or the orbital frontal cortex (OFC) given that these neural systems contribute to reward valuation. Systemic dopamine receptor antagonism attenuated anticipatory responding during training sessions but did not prevent the change in reward preference elicited by incurred temporal costs. OFC lesions had no effect on anticipatory responding during training or on the change in reward preference. These findings collectively illustrate that the neural systems involved with economic assessments of reward value are not contributing to changes in subjective preference.

Multigenerational Differences in Career Preferences, Reward Preferences and Work Engagement among Indian Employees

The purpose of the present study is to empirically examine the multigenerational differences in career preferences, reward preferences and work engagement among three generations (senior generation, generation X and generation Y). Data were collected with the help of an online questionnaire from 653 working executives working in different Indian public and private organizations. Significance of differences in career preference, reward preference and work engagement among generations was analyzed with the help of analysis of variance (ANOVA) followed by post hoc Tukey test. Findings of the present study indicate that there is a significant difference in career preferences and work engagement among the three studied generations. Additionally, there is no significant difference in reward preferences among the three studied generations. The present article describes and discusses these findings and the global implications of the same for managers.