Recent research suggests that obesity is linked to prominent alterations in learning and decision-making. This general difference may also underlie the preference for immediately consumable, highly palatable but unhealthy and high-calorie foods. Such poor food-related inter-temporal decision-making can explain weight gain; however, it is not yet clear whether this deficit can be generalized to other domains of inter-temporal decision-making, for example financial decisions. Further, little is known about the stability of decision-making behavior in obesity, especially in the presence of rewarding cues. To answer these questions, obese and lean participants (n = 52) completed two sessions of a a computerized monetary delay discounting task, including a novel priming paradigm. In the first session, general differences between groups in financial delay discounting were measured. In the second session, I tested the general stability of discount rates. Additionally, participants were primed by affective visual cues of different contextual categories before making financial decisions. I found that the obese group showed stronger discounting of future monetary rewards than the lean group, but groups did not differ in their general stability between sessions nor in their sensitivity toward changes in reward magnitude. In the obese group, a fast decrease of subjective value over time was directly related to a higher tendency for opportunistic eating. Obese in contrast to lean people were primed by the affective cues, showing a sex-specific pattern of priming direction. The findings demonstrate that environments rich of cues, aiming at inducing unhealthy consumer decisions, can be highly detrimental for obese people. It also underscores that obesity is not merely a medical condition but has a strong cognitive component, meaning that current dietary and medical treatment strategies may fall too short.:1. Introduction 1.1 Obesity as a global epidemic 1.2 Etiology of the obesity epidemic 1.3 The cognitive component – impulsivity as a potential risk factor for the development of obesity 1.4 Impulsivity 1.4.1 Impulsivity and obesity – current knowledge 1.4.2 Outlook: impulsivity and eating behavior in obesity 1.5 Delay discounting 1.5.1 Neurological correlates of delay discounting 1.6 Delay discounting and obesity 1.6.1 First aim of the present thesis: establishing a general difference in delay discounting task performance between lean and obese 1.7 General stability of decision-making preferences 1.7.1 Stability towards external cues / Priming 1.7.2 Priming and obesity 1.8 Aim of this thesis 2. Original publication 3. Summary 3.1 Introduction and research questions 3.2 Methods 3.3 Results and discussion 3.4 Implications 4. Bibliography 5. Anlagen

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This study presented meat consumption as an environmentally relevant behavior (ERB) and examined how the delay to an environmental loss might affect peoples’ decisions to eat meat. Participants completed a delay discounting survey where they selected what percentage of meat they would eliminate from their diet based on varying delays to rising sea levels flooding of their neighborhood. After watching a brief educational video, participants completed the survey a second time to examine whether the video had any influence on discounting rates in the post-survey. Participants also completed the 27-Item Monetary Choice Questionnaire (MCQ; Kirby & Marakovic, 1996) in order to compare individuals’ monetary discounting rates to their environmental discounting rates. Data were analyzed using calculations of area under the curve (AUC) and Mazur’s (1987) hyperbolic discounting equation. Results showed that the average percentage of meat that people chose to eliminate from their diets decreased as a function of the delay to the environmental loss, the educational video was effective in reducing environmental discounting rates, and discounting rates for monetary outcomes were positively and significantly correlated with discounting rates for environmental outcomes. Implications, limitations, and avenues for future research are discussed.

The purpose of the current study is to evaluate whether ACT techniques, such as acceptance activities, has an impact on an individual’s delayed and/or probabilistic discounting behavior measured by discounting tasks and other self-reported measures related to eating behaviors and health. Participants in an intervention and control group completed a monetary food and disease delay discounting survey before and after completing either a brief ACT session or completing a control activity. Thirty-six undergraduates participated in the present study and a pre-, post-control groups design was utilized to evaluate the effects of the intervention. Independent t-tests were conducted, and the results of those analyses showed that ACT was no effective in decreasing discounting on the monetary food, and disease discounting survey pre-test AUC 0.9147 (SD=0.1295) and post-test survey AUC 0.8794 (SD=0.1737). There were no statistically significant changes for the ACT or control group Implications of these findings and future research are discussed. Keywords: ACT, discounting, obesity, students

Indiana University-Purdue University Indianapolis (IUPUI) / Increased delay discounting (DD) has been associated with and is theorized to contribute to alcoholism and substance abuse. It is also been associated with numerous other mental disorders and is believed to be a trans-disease process (i.e., a process that occurs in and contributes to multiple different pathologies). Consequently insights gained from studying DD are likely to apply to many different diseases. Studies on the neurobiological underpinnings of DD have two main interpretations. The first interpretation is that two different neurobehavioral systems exist, one favoring delayed rewards (executive system) and one favoring immediate rewards (impulsive system), and the system with the greater relative activation determines choice made by an individual. Alternatively, a single valuation system may exist. This system integrates different information about outcomes and generates a value signal that then guides decision making. Preclinical investigations have steered clear of these two different interpretations and rather focused on the role of individual structures in DD. One such structure, the rat mPFC, may generate an outcome representation of delayed rewards that is critically involved in attributing value to delayed rewards. Moreover, there is evidence indicating the rat mPFC may correspond to the primate dlPFC, an executive system structure. The current body of work set about testing the hypotheses that the mPFC is necessary for attributing value to delayed rewards and that decreasing the activity in an executive system area, and thus the executive system, shifts inter-temporal preference towards immediate rewards. To this end the rat mPFC was inactivated using an hM4Di inhibitory designer receptor exclusively activated by designer drugs (DREADD; experiment 1) or microinjections of tetrodotoxin (TTX; experiment 2) while animals completed an adjusting amount DD task. Activation of the hM4Di inhibitory DREADD receptor caused a decrease in DD, opposite of what was predicted. Electrophysiological recordings revealed a subpopulation of neurons actually increased their firing in response to hM4Di receptor activation, potentially explaining the unpredicted results. Microinjections of TTX to completely silence neural activity in the mPFC failed to produce a change in DD. Together both results indicate that mPFC activity is capable of manipulating but is not necessary for DD and the attribution of value to the delayed reward. Consequently, a secondary role for the rat mPFC in DD is proposed in line with single valuation system accounts of DD. Further investigations determining the primary structures responsible for sustaining delayed reward valuation and how manipulating the mPFC may be a means to decrease DD are warranted, and continued investigation that delineates the neurobiological processes of delayed reward valuation may provide valuable insight to both addiction and psychopathology.

It is well documented that adolescent substance use is associated with deficits in brain function and behavior. However, possible deficits that predate substance use initiation remain poorly characterized in preadolescents at-risk for developing substance use disorder (SUD). To characterize potential brain and behavioral differences that predate substance use, substance naïve preadolescents, ages 11–12, were recruited into three groups to complete functional magnetic resonance imaging delay discounting: (1) High-risk youth (n=35) with a family history of SUD and externalizing psychiatric disorders, (2) psychiatric controls (n=35) with no family history of SUD, but equivalent externalizing psychiatric disorders as high-risk youth, and (3) healthy controls (n=29) with no family history of SUD and minimal psychopathology. While no behavioral differences between groups were identified, there were group differences in posterior cingulate cortex (PCC) function during decision making. Specifically, the high-risk group showed stronger deactivation of the PCC than healthy controls. These results suggest that high-risk preadolescents may need to suppress activity of key nodes of the default mode network (a task negative network) to a greater extent to properly allocate attention to the task.

Indiana University-Purdue University Indianapolis (IUPUI) / It is well documented that adolescent substance use is associated with deficits in brain function and behavior. However, possible deficits that predate substance use initiation remain poorly characterized in preadolescents at-risk for developing substance use disorder (SUD). To characterize potential brain and behavioral differences that predate substance use, substance naïve preadolescents, ages 11–12, were recruited into three groups to complete functional magnetic resonance imaging delay discounting: (1) High-risk youth (n=35) with a family history of SUD and externalizing psychiatric disorders, (2) psychiatric controls (n=35) with no family history of SUD, but equivalent externalizing psychiatric disorders as high-risk youth, and (3) healthy controls (n=29) with no family history of SUD and minimal psychopathology. While no behavioral differences between groups were identified, there were group differences in posterior cingulate cortex (PCC) function during decision making. Specifically, the high-risk group showed stronger deactivation of the PCC than healthy controls. These results suggest that high-risk preadolescents may need to suppress activity of key nodes of the default mode network (a task negative network) to a greater extent to properly allocate attention to the task.

In this thesis, I will explore the idea that choices between present, smaller value options and future, larger value options depend on how much individuals trust the future to deliver the reward. Due to this aspect of trust, the individual must build their estimate of trust based on information for their present environment and their future expectations. This estimate of future trust can change across different time points in the same environment (i.e., before and after a national election) and between environments in the same time point (i.e., between two countries experiencing different economic rates of change). In this set of presented experiments, I will explore the link between decision environment and delay discounting, as well as the relationship between the contents of future perception and delay discounting. These two experiments will test differences in delay discounting (a) across two economic systems (China and the U.S.), as well as (b) before and after a national election (2018 U.S. Midterms). The results of the different decision environments study show that the delay discounting rates are significantly different across the two countries, specifically within the framing of present and future. These differences are not explained by differences in culture effects or individual differences in personality traits, suggesting that difference in environment is driving the effect. The results from the Midterm election experiments show evidence for differences in delay discounting between political identities and income groups. There are also differences in how these two groups perceive the contents of their future before and after the election. Specifically with evidence that negative future projection corresponds with increased delay discounting. Overall, these experiments show that delay discounting can be affected by the way information is framed within an environment and how we expect our environments to change over time.

<p>Preclinical rodent models were used to investigate the neural signatures of strategy change during the delay discounting decision making task. Neural signatures were assessed using advanced statistical techniques (de-mixed principal component analysis). </p>

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