Age-related differences in neural activities during risk taking as revealed by functional MRI

Previous research has clearly documented that risky decision making is different in young and older adults. Yet, there has been a relative dearth of research that seeks to understand such age-related changes in the neural activities associated with risk taking. To address this research issue, 21 men (12 young men, mean age 29.9±6.2 years and 9 older men, mean age 65.2±4.2 years) performed a risky-gains task while their brain activities were monitored by an fMRI scanner. The older adults, relative to their younger peers, presented with contralateral prefrontal activity, particularly at the orbitofrontal cortex. Furthermore, stronger activation of the right insula was observed for the older-aged participants compared to the younger-aged adults. The findings of this study are consistent with the a priori speculations established in accordance with the HAROLD model as well as previous findings. Findings of this study suggest that when making risky decisions, there may be possible neuropsychological mechanisms underlying the change in impulsive and risk-taking behaviors during the course of natural ageing. © 2007 The Author(s).published_or_final_versio

What are the odds? A Functional Imaging Study on Loss Anticipation, Positive Punishment and Negative Reinforcement in Problem Gamblers and Healthy Controls

Objective: With this study, we aim to arrive at a better understanding of the neural mechanisms underlying the anticipation of losses due to unpleasant electric shock stimuli. According to prospect theory – currently the most important descriptive model of decision making under uncertainty in economics – subjects overweight small probabilities and underweight high probabilities. Here, we analyzed to what extent prospect theory is manifested in biological data. Does the human brain process aversive contingencies of decisions in a nonlinear manner according to the probability weighting function underlying prospect theory? Which brain regions process certainty or uncertainty regarding an outcome regardless of its valence? How do individuals with problematic gambling habits differ in these entities? Methods: The present study included a total of 83 participants (22 problem gamblers, 18 habitual gamblers, 23 age-matched subjects and 20 young control subjects). Each participant was evaluated by psychologists through a semi-structured interview and the self-reported Southern Oaks Gambling Scale. The study participants engaged in a card game in which unambiguous situations with various risk levels for aversive events (unpleasant but not painful electric shocks) were created. Apart from neural responses during anticipation of an aversive event, our paradigm allowed us to measure how neural activity during expectation is modulated by the probability of the outcome. Furthermore, we used the participants’ attitudes towards risk to account for the subjective evaluation of probabilities, as suggested by prospect theory. Results: We confirmed existing knowledge about the active network during anticipation of aversive events in a large sample. Specifically, in response to our experimental stimuli, the BOLD (blood oxygen level dependent) signal increased in the anterior and medial cingulate cortex, the anterior insula, the amygdala, the thalamus and the medial frontal regions. Based on economic studies and on our previous behavioural results, we modelled the expected outcomes according to uncertainty and prospect theory. With increasing chances of avoiding punishment, we found that the BOLD signal increased in the orbitofrontal cortex, the striatum, the hippocampus, the precuneus, and the posterior cingulate cortex. Conversely, with increasing certainty of a positive or negative outcome (U-shaped from most certain loss to no loss), we found activation patterns in the medial superior frontal cortex, the anterior cingulate cortex, the anterior insula, the frontopolar prefrontal cortex and the angular gyrus. Furthermore, we found evidence for group differences in cerebral activation in the bilateral superior temporal pole, the anterior insula and the medial cingulate cortex during the perception of distinct probability levels according to the nonlinear probability weighting function. Interestingly, these regions are relevant both in loss anticipation paradigms and in functional imaging studies describing pathological gambling. Conclusion: Our results support the concept that the neural response to anticipation is determined by its valence. Although it has frequently been reported that gamblers and non-gambling individuals show differences in reward anticipation, during loss anticipation gambling participants do not differ in their neural activation patterns. We also tested whether specific regions of the brain follow a nonlinear brain response according to prospect theory and the certainty of an outcome. When their BOLD responses during probability perception were compared, non-gambling and gambling individuals did show differences in the perception of probabilities. This provides new evidence that simultaneously occurring cognitive processes are represented in different sets of brain regions. Specifically, neurobiological correlates of loss anticipation were found in areas known to be involved in dopaminergic reinforcement learning and in the corticolimbic circuit, while regions known to subserve decision making, conflict monitoring and punishment showed correlation with the certainty of the outcome

A Behavioral and Neural Evaluation of Prospective Decision-Making under Risk

Making the best choice when faced with a chain of decisions requires a person to judge both anticipated outcomes and future actions. Although economic decision-making models account for both risk and reward in single-choice contexts, there is a dearth of similar knowledge about sequential choice. Classical utility-based models assume that decision-makers select and follow an optimal predetermined strategy, regardless of the particular order in which options are presented. An alternative model involves continuously reevaluating decision utilities, without prescribing a specific future set of choices. Here, using behavioral and functional magnetic resonance imaging (fMRI) data, we studied human subjects in a sequential choice task and use these data to compare alternative decision models of valuation and strategy selection. We provide evidence that subjects adopt a model of reevaluating decision utilities, in which available strategies are continuously updated and combined in assessing action values. We validate this model by using simultaneously acquired fMRI data to show that sequential choice evokes a pattern of neural response consistent with a tracking of anticipated distribution of future reward, as expected in such a model. Thus, brain activity evoked at each decision point reflects the expected mean, variance, and skewness of possible payoffs, consistent with the idea that sequential choice evokes a prospective evaluation of both available strategies and possible outcomes

Die Rolle der Zielnähe und der investierten Anstrengung für den erwarteten Wert einer Handlung

In human neuroscientific research, there has been an increasing interest in how the brain computes the value of an anticipated outcome. However, evidence is still missing about which valuation related brain regions are modulated by the proximity to an expected goal and the previously invested effort to reach a goal. The aim of this dissertation is to investigate the effects of goal proximity and invested effort on valuation related regions in the human brain. We addressed this question in two fMRI studies by integrating a commonly used reward anticipation task in differential versions of a Multitrial Reward Schedule Paradigm. In both experiments, subjects had to perform consecutive reward anticipation tasks under two different reward contingencies: in the delayed condition, participants received a monetary reward only after successful completion of multiple consecutive trials. In the immediate condition, money was earned after every successful trial. In the first study, we could demonstrate that the rostral cingulate zone of the posterior medial frontal cortex signals action value contingent to goal proximity, thereby replicating neurophysiological findings about goal proximity signals in a homologous region in non-human primates. The findings of the second study imply that brain regions associated with general cognitive control processes are modulated by previous effort investment. Furthermore, we found the posterior lateral prefrontal cortex and the orbitofrontal cortex to be involved in coding for the effort-based context of a situation. In sum, these results extend the role of the human rostral cingulate zone in outcome evaluation to the continuous updating of action values over a course of action steps based on the proximity to the expected reward. Furthermore, we tentatively suggest that previous effort investment invokes processes under the control of the executive system, and that posterior lateral prefrontal cortex and the orbitofrontal cortex are involved in an effort-based context representation that can be used for outcome evaluation that is dependent on the characteristics of the current situation.Derzeit besteht im Bereich der Neurowissenschaften ein großes Interesse daran aufzuklären, auf welche Weise verschiedene Variablen die Wertigkeit eines erwarteten Handlungsziels beeinflussen bzw. welche Hirnregionen an der Repräsentation der Wertigkeit eines Handlungsziels beteiligt sind. Die meisten Untersuchungen beziehen sich dabei auf Einflussgrößen wie die erwartete Belohnungshöhe, die Wahrscheinlichkeit, mit der ein bestimmtes Ereignis eintritt, oder die Dauer bis zum Erhalt einer Belohnung. Bisher liegen jedoch kaum Untersuchungen vor bezüglich zweier anderer Variablen, die ebenfalls den erwarteten Wert eines Handlungsergebnisses beeinflussen. Das sind (a) die Nähe zu dem erwarteten Ziel und (b) die bisher investierte Anstrengung, um ein Ziel zu erreichen. Das Ziel der vorliegenden Dissertation ist zu untersuchen, wie die Nähe zum Ziel und die bisher investierte Anstrengung Gehirnregionen beeinflussen, die mit der Repräsentation von Wertigkeit im Zusammenhang stehen. Dazu führten wir zwei fMRT-Studien durch, in denen wir eine klassische Belohnungs-Antizipationsaufgabe in unterschiedliche Versionen eines „Multitrial Reward Schedule“ Paradigmas integriert haben. Das bedeutet, dass die Probanden Belohnungs-Antizipationsaufgaben unter zwei unterschiedlichen Belohnungskontingenzen bearbeiteten: In der verzögerten Bedingung erhielten die Probanden einen Geldbetrag nach der erfolgreichen Bearbeitung von mehreren aufeinanderfolgenden Aufgaben, in der direkten Bedingung dagegen nach jeder korrekt ausgeführten Aufgabe. In der ersten Studie konnte eine sukzessiv ansteigende Aktivität in Abhängigkeit zur Zielnähe in der rostralen cingulären Zone identifiziert werden. Das deutet darauf hin, dass dieses Areal den Wert einer Handlung in Abhängigkeit zur Nähe zum Ziel kodiert. Die Ergebnisse der zweiten Studie zeigten, dass die bisher investierte Anstrengung kortikale Regionen moduliert, die klassischerweise mit kognitiven Kontrollfunktionen in Zusammenhang gebracht werden. Außerdem repräsentierten der posteriore laterale präfrontale Cortex und der orbitofrontale Cortex den motivationalen Kontext eines Trials anhand des Risikos des Verlustes von bisher investierter Anstrengung. Insgesamt weisen diese Befunde darauf hin, dass die rostrale cinguläre Zone eine entscheidende Rolle spielt für die Kontrolle sequenzieller Handlungsstufen, die auf eine verzögerte Belohnung ausgerichtet sind. Diese Kontrollfunktion scheint auf der kontinuierlichen Aktualisierung des Wertes einer Handlungsstufe zu basieren, der von der aktuellen Zielnähe bestimmt wird. Die Befunde der zweiten Studie lassen darauf schließen, dass sich die bisher investierte Anstrengung zur Erreichung eines Handlungsziels auf die Bereitstellung von allgemeinen kognitiven Ressourcen auswirkt. Das Risiko des Verlustes von bisher investierter Anstrengung kann außerdem ein kontextuelles Merkmal der Situation darstellen, das als Bezugsrahmen für die Evaluation des erwarteten Wertes dienen kann

More equal than others: the neural basis of unfairness and inequality perception in the Ultimatum Game

As the research on the Ultimatum Game (UG) has clearly demonstrated, the model of homo economicus fails to predict human behavior in a number of situations.. Many interpretations have been put forward in order to explain why players do not simply aim at maximizing their monetary payoff. For instance, models of social preferences (see e.g., Camerer, 2003) try to provide a formal explanation for the apparently irrational behavior of people facing a certain kind of interactive situation. In chapter 1, a more detailed description of these accounts will be given, focusing especially on the specific case of the UG in relation to negative reciprocity (Rabin, 1993) and inequity aversion (Fehr & Schmidt, 1999). From a psychological viewpoint, negative emotions, such as anger and frustration, elicited by the unfair treatment, are accounted to cause rejections (Pillutla and Murnigham, 1996)

Smaller Regional Gray Matter Volume in Homeless African American Cocaine-Dependent Men: A Preliminary Report

Models of addiction include abnormalities in parts of the brain involving executive function/inhibitory control. Although previous studies have reported evidence of structural abnormalities in cocaine-dependent individuals, none have specifically targeted the homeless. The present preliminary study investigated brain structure in such an understudied group, homeless, crack-cocaine-dependent African American men (n = 9), comparing it to that in healthy controls (n = 8). Structural data were analyzed using voxel based morphometry (VBM) and a regions of interest (ROI) analysis. Homeless cocaine-dependent individuals had smaller gray matter volume in dorsolateral prefrontal cortex, anterior cingulate, the cerebellum, insula, and superior temporal gyrus. Most of these areas subserve executive function or inhibitory control. These results are similar to those found in most previous studies of non-homeless cocaine-dependent individuals. Reduced gray matter in executive function/inhibitory control regions of the brain in cocaine-dependent individuals may be a preexisting risk factor for the development of addiction and/or a consequence of drug abuse

Social and Non-social Brain Areas in Risk Behaviour: The Role of Social Context

This work was supported by the Spanish Ministry of Economy, Industry, and Competitiveness through a grant awarded (PSI2016-80558-R to A.Catena) and a postdoctoral contract of the University of Granada (to S. Baltruschat) .The human brain contains social areas that become active when interacting with another human. These are located in the ventral prefrontal and mediodorsal cortices, adjacent to areas involved in reward processing and cognitive control. Human behaviour is strongly influenced by the social context. This is particularly evident when observing greater risk propensity in the presence of a peer, particularly during adolescence and emerging adulthood. We explored the widely held view that enhanced risk propensity is the consequence of weak cognitive control. We used brain activity, estimated from EEG recordings in a sample of 114 emerging adult dyads whilst performing a risk perception task, to predict risk behaviour in a subsequent driving simulation task. Being with a peer reduced the ability to discriminate riskiness in images of traffic scenes, biased responses towards the perception of no-risk, and increased the rate of accidents in the driving simulation. Risk perception involved three sets of clusters showing activity only when being with a peer, only when being alone, and in both social contexts. Functional connectivity between the clusters accounted for the later driving simulation performance depending on the peer’s presence. In the light of our findings, greater risk-taking, when a peer is present, seems to be triggered by the activation of a different, less efficient brain network for risk-processing.Spanish Ministry of Economy, Industry, and Competitiveness PSI2016-80558-RUniversity of Granad