Decision making and feedback processing investigated with event-related potentials

Die Verarbeitung externer Feedbackreize ist essentiell für das Treffen von Entscheidungen. Die aktuelle neurowissenschaftliche Forschung bezüglich Entscheidungsfindung befasste sich bis dato hauptsächlich mit negativem Feedback und seinen Konsequenzen. Die vorliegende Dissertation beschäftigte sich mit neuronalen Prozessen in Zusammenhang mit positiven Feedbackreizen und Persönlichkeitseigenschaften. Zwei Komponenten des ereigniskorrelierten Potentials (EKP), die Feedback-Related Negativity (FRN) und die P300 Komponente wurden im Kontext von positiven und negativen, sowie erwarteten und unerwarteten Feedbackreizen untersucht. Es wurden zwei Elektroenzephalogramm (EEG) Studien durchgeführt, in denen eine Spielaufgabe als Experimentalparadigma vorgegeben wurde. Die Feedbackreize bestanden aus Zahlen, die direkt einen Geldgewinn oder -verlust andeuteten, sowie aus fröhlichen und ärgerlichen Gesichtern, die indirekt einen Geldgewinn oder -verlust anzeigten. In getrennten Manuskripten wurde der Klärung zweier Forschungsfragen nachgegangen. Das erste Manuskript beschäftigte sich mit der Frage, ob unerwartetes positives Feedback eine vergleichbare negative Auslenkung des EKPs hervorruft wie es bei der FRN nach der Präsentation von negativem Feedback zu beobachten ist. Deshalb wurden die Feedbackdimensionen Erwartung und Valenz experimentell manipuliert. Die daraus resultierenden Ergebnisse deuten darauf hin, dass sowohl Erwartung als auch Valenz einen vergleichbaren Einfluss auf die Amplitudenmodulation der FRN haben. Eben diese FRN Amplituden waren erhöht nach unerwartetem und negativem Feedback. P300 Amplituden wurden hingegen nur durch die Erwartung des Reizes moduliert, nicht durch dessen Valenz. Daraus resultiert die wissenschaftliche Hypothese, die FRN Amplitudenmodulation als Signal des Verstärkungslernens zu betrachten, welches saliente Ereignisse anzeigt. Das zweite Manuskript beschäftigt sich mit der Frage ob antisoziale Persönlichkeitseigenschaften die FRN Amplitudenmodulation in Bezug auf Feedbackerwartung und – valenz beeinflussen. Es wurde der Einfluss von numerischen im Gegensatz zu emotionalen Feedbackreizen in jenen Versuchspersonen untersucht, die entweder hohe oder niedrige Werte auf einer psychologischen Skala zur Erfassung von antisozialen Persönlichkeitseigenschaften aufwiesen. Die Ergebnisse deuten darauf hin, dass es die Dimension der Feedbackerwartung und nicht der -valenz ist, die zwischen sozialern und antisozialeren Individuen unterscheidet. 96 Zukünftige Forschung zu Feedbackverarbeitung sollte versuchen die theoretischen Ansätze mit aktuellen Forschungsergebnissen in Einklang zu bringen, um das Verständnis zugrunde liegender Prozesse von Entscheidungsfindung besser verstehen zu können.The processing of external feedback cues is crucial for decision making processes. Recent neuroscientific research has mainly focused on the processing of negative feedback events. The present project investigated neuronal processes related to positive feedback cues and personality characteristics. Two components of the event-related potential (ERP), the Feedback-Related Negativity (FRN) and the P300 were investigated in the context of positive and negative expected and unexpected feedback outcomes. Two EEG-studies were conducted applying a gambling paradigm where feedback stimuli consisted either of numbers indicating direct monetary gain and loss or of happy and angry faces indicating indirect monetary gain and loss. Two research questions were addressed in separate scientific manuscripts. The first manuscript addressed the questions whether unexpected positive feedback elicits a negative ERP deflection in the latency range of the FRN component. Feedback expectancy and feedback valence were manipulated in the experimental paradigm. Results indicate that expectancy as well as valence had comparable impact on FRN amplitude modulation. FRN amplitudes were larger after unexpected compared to expected, and after negative compared to positive feedback. P300 amplitudes were modulated by expectancy – unexpected feedback conditions yielding largest P300 amplitudes – but not by valence. Thus, the proposal is made to interpret FRN amplitude modulation in terms of a reinforcement learning signal which is indicating motivationally salient outcomes. The second manuscript addressed the question whether antisocial personality characteristics influence FRN amplitude modulation related to feedback expectancy and feedback valence. The effect of numerical versus emotional feedback stimuli was investigated in individuals scoring low and high on a psychological measure of antisociality. Results indicate that it is the dimension of feedback expectancy and not of valence that differentiates social from more antisocial individuals. Future research on feedback processing should try to integrate the different theoretical frameworks and recent findings to promote the understanding of the underlying cognitive processes

Social and non-social feedback stimuli lead to comparable levels of reward learning and reward responsiveness in an online probabilistic reward task

Social stimuli seem to be processed more easily and efficiently than non-social stimuli. The current study tested whether social feedback stimuli improve reward learning in a probabilistic reward task (PRT), in which one response option is usually rewarded more often than the other via presentation of non-social reward stimuli. In a pre-registered online study with 305 participants, 75 participants were presented with a non-social feedback stimulus (a star) and information about gains, which is typically used in published PRT studies. Three other groups (with 73–82 participants each) were presented with one of three social feedback stimuli: verbal praise, an attractive happy face, or a “thumbs up”-picture. The data were analysed based on classical signal detection theory, drift diffusion modelling, and Bayesian analyses of null effects. All PRT variants yielded the expected behavioural preference for the more frequently rewarded response. There was no processing advantage of social over non-social feedback stimuli. Bayesian analyses further supported the observation that social feedback stimuli neither increased nor decreased behavioural preferences in the PRT. The current findings suggest that the PRT is a robust experimental paradigm independent of the applied feedback stimuli. They also suggest that the occurrence of a processing advantage for social feedback stimuli is dependent on the experimental task and design.publishedVersio

Hungry for compliments? Ghrelin is not associated with neural responses to social rewards or their pleasantness

The stomach-derived hormone ghrelin motivates food search and stimulates food consumption, with highest plasma concentrations before a meal and lowest shortly after. However, ghrelin also appears to affect the value of non-food rewards such as interaction with rat conspecifics, and monetary rewards in humans. The present pre-registered study investigated how nutritional state and ghrelin concentrations are related to the subjective and neural responses to social and non-social rewards. In a cross-over feed-and-fast design, 67 healthy volunteers (20 women) underwent functional magnetic resonance imaging (fMRI) in a hungry state and after a meal with repeated plasma ghrelin measurements. In task 1, participants received social rewards in the form of approving expert feedback, or non-social computer reward. In task 2, participants rated the pleasantness of compliments and neutral statements. Nutritional state and ghrelin concentrations did not affect the response to social reward in task 1. In contrast, ventromedial prefrontal cortical activation to non-social rewards was reduced when the meal strongly suppressed ghrelin. In task 2, fasting increased activation in the right ventral striatum during all statements, but ghrelin concentrations were neither associated with brain activation nor with experienced pleasantness. Complementary Bayesian analyses provided moderate evidence for a lack of correlation between ghrelin concentrations and behavioral and neural responses to social rewards, but moderate evidence for an association between ghrelin and non-social rewards. This suggests that ghrelin’s influence may be restricted to non-social rewards. Social rewards implemented via social recognition and affirmation may be too abstract and complex to be susceptible to ghrelin’s influence. In contrast, the non-social reward was associated with the expectation of a material object that was handed out after the experiment. This may indicate that ghrelin might be involved in anticipatory rather than consummatory phases of reward

All about the Money – External Performance Monitoring is Affected by Monetary, but Not by Socially Conveyed Feedback Cues in More Antisocial Individuals

This study investigated the relationship between feedback processing and antisocial personality traits measured by the PSSI questionnaire (Kuhl and Kazén, 1997) in a healthy undergraduate sample. While event-related potentials [feedback related negativity (FRN), P300] were recorded, participants encountered expected and unexpected feedback during a gambling task. As recent findings suggest learning problems and deficiencies during feedback processing in clinical populations of antisocial individuals, we performed two experiments with different healthy participants in which feedback about monetary gains or losses consisted either of social–emotional (facial emotion displays) or non-social cues (numerical stimuli). Since the FRN and P300 are both sensitive to different aspects of feedback processing we hypothesized that they might help to differentiate between individuals scoring high and low on an antisocial trait measure. In line with previous evidence FRN amplitudes were enhanced after negative and after unexpected feedback stimuli. Crucially, participants scoring high on antisocial traits displayed larger FRN amplitudes than those scoring low only in response to expected and unexpected negative numerical feedback, but not in response to social–emotional feedback – irrespective of expectancy. P300 amplitudes were not modulated by antisocial traits at all, but by subjective reward probabilities. The present findings indicate that individuals scoring high on antisociality attribute higher motivational salience to monetary compared to emotional–social feedback which is reflected in FRN amplitude enhancement. Contrary to recent findings, however, no processing deficiencies concerning social–emotional feedback stimuli were apparent in those individuals. This indicates that stimulus salience is an important aspect in learning and feedback processes in individuals with antisocial traits which has potential implications for therapeutic interventions in clinical populations

Hungry for compliments? Ghrelin is not associated with neural responses to social rewards or their pleasantness

The stomach-derived hormone ghrelin motivates food search and stimulates food consumption, with highest plasma concentrations before a meal and lowest shortly after. However, ghrelin also appears to affect the value of non-food rewards such as interaction with rat conspecifics, and monetary rewards in humans. The present pre-registered study investigated how nutritional state and ghrelin concentrations are related to the subjective and neural responses to social and non-social rewards. In a cross-over feed-and-fast design, 67 healthy volunteers (20 women) underwent functional magnetic resonance imaging (fMRI) in a hungry state and after a meal with repeated plasma ghrelin measurements. In task 1, participants received social rewards in the form of approving expert feedback, or non-social computer reward. In task 2, participants rated the pleasantness of compliments and neutral statements. Nutritional state and ghrelin concentrations did not affect the response to social reward in task 1. In contrast, ventromedial prefrontal cortical activation to non-social rewards was reduced when the meal strongly suppressed ghrelin. In task 2, fasting increased activation in the right ventral striatum during all statements, but ghrelin concentrations were neither associated with brain activation nor with experienced pleasantness. Complementary Bayesian analyses provided moderate evidence for a lack of correlation between ghrelin concentrations and behavioral and neural responses to social rewards, but moderate evidence for an association between ghrelin and non-social rewards. This suggests that ghrelin’s influence may be restricted to non-social rewards. Social rewards implemented via social recognition and affirmation may be too abstract and complex to be susceptible to ghrelin’s influence. In contrast, the non-social reward was associated with the expectation of a material object that was handed out after the experiment. This may indicate that ghrelin might be involved in anticipatory rather than consummatory phases of reward.publishedVersio

Single-centre, non-randomised clinical trial at a tertiary care centre to investigate 1-year changes in social experiences and biomarkers of well-being after bariatric surgery in individuals with severe obesity: protocol for the Bariatric Surgery and Social Experiences (BaSES) study

Introduction Obesity is linked to increased loneliness and less enjoyment of social interactions. While bariatric surgery is the most effective treatment targeting severe obesity, there is limited understanding as to whether patients experience social interactions differently after surgery. The Bariatric Surgery and Social Experiences study is designed to assess potential changes in how much patients enjoy and engage in daily social interactions 1 year after Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). Methods and analysis Single-centre, non-randomised clinical trial carried out at the Department of Endocrinology, Obesity and Nutrition at Vestfold Hospital Trust, Norway. Eligible patients (N=113) will undergo either RYGB, SG or single anastomosis sleeve ileal (SASI) bypass. The primary outcome measure is change in the social experience score (assessed with a questionnaire) from a presurgery to a follow-up assessment 1 year after RYGB and SG. The respective changes after SASI bypass will be assessed and considered exploratory. Ethics and dissemination The most recent protocol version of this study was reviewed and approved by the Regional Committee for Medical Research Ethics South East Norway (REK sør-øst A) on 29 August 2022 (ref: 238406). The results will be disseminated to academic and health professional audiences and the public via publications in international peer-reviewed journals and conferences.publishedVersio

Do we care about the powerless third? An ERP study of the three-person ultimatum game

Recent years have provided increasing insights into the factors affecting economic decision-making. Little is known about how these factors influence decisions that also bear consequences for other people. We examined whether decisions that also affected a third, passive player modulate the behavioral and neural responses to monetary offers in a modified version of the three-person ultimatum game. We aimed to elucidate to what extent social preferences affect early neuronal processing when subjects were evaluating offers that were fair or unfair to themselves, to the third player, or to both. As an event-related potential (ERP) index for early evaluation processes in economic decision-making, we recorded the medial frontal negativity (MFN) component in response to such offers. Unfair offers were rejected more often than equitable ones, in particular when negatively affecting the subject. While the MFN amplitude was higher following unfair as compared to fair offers to the subject, MFN amplitude was not modulated by the shares assigned to the third, passive player. Furthermore, rejection rates and MFN amplitudes following fair offers were positively correlated, as subjects showing lower MFN amplitudes following fair offers tended to reject unfair offers more often—but only if those offers negatively affected their own payoff. Altogether, the rejection behavior suggests that humans mainly care about a powerless third when they are confronted with inequality as well. The correlation between rejection rates and the MFN amplitude supports the notion that this ERP component is also modulated by positive events and highlights how our expectations concerning other humans' behavior guide our own decisions. However, social preferences like inequality aversion and concern for the well-being of others are not reflected in this early neuronal response, but seem to result from later, deliberate and higher-order cognitive processes

Ghrelin is related to lower brain reward activation during touch

The gut hormone ghrelin drives food motivation and increases food intake, but it is also involved in the anticipation of and response to rewards other than food. This pre-registered study investigated how naturally varying ghrelin concentrations affect the processing of touch as a social reward in humans. Sixty-seven volunteers received slow caressing touch (so-called CT-targeted touch) as a social reward and control touch on their shins during 3T functional imaging on two test days. On one occasion, participants were fasted, and on another, they received a meal. On each occasion, plasma ghrelin was measured at three time points. All touch was rated as more pleasant after the meal, but there was no association between ghrelin concentrations and pleasantness. CT-targeted touch was rated as the most pleasant and activated somatosensory and reward networks (whole brain). A region-of-interest in the right medial orbitofrontal cortex (mOFC) showed lower activation during all touches, the higher the ghrelin concentrations were. During CT-targeted touch, a larger satiety response (ghrelin decrease after the meal) was associated with higher mOFC activation, and this mOFC activation was associated with higher experienced pleasantness. Overall, higher ghrelin concentrations appear to be related to a lower reward value for touch. Ghrelin may reduce the value of social stimuli, such as touch, to promote food search and intake in a state of low energy. This suggests that the role of ghrelin goes beyond assigning value to food reward.publishedVersio

The pulvinar nucleus and antidepressant treatment : dynamic modeling of antidepressant response and remission with ultra-high field functional MRI

Functional magnetic resonance imaging (fMRI) successfully disentangled neuronal pathophysiology of major depression (MD), but only a few fMRI studies have investigated correlates and predictors of remission. Moreover, most studies have used clinical outcome parameters from two time points, which do not optimally depict differential response times. Therefore, we aimed to detect neuronal correlates of response and remission in an antidepressant treatment study with 7 T fMRI, potentially harnessing advances in detection power and spatial specificity. Moreover, we modeled outcome parameters from multiple study visits during a 12-week antidepressant fMRI study in 26 acute (aMD) patients compared to 36 stable remitted (rMD) patients and 33 healthy control subjects (HC). During an electrical painful stimulation task, significantly higher baseline activity in aMD compared to HC and rMD in the medial thalamic nuclei of the pulvinar was detected (p = 0.004, FWE-corrected), which was reduced by treatment. Moreover, clinical response followed a sigmoid function with a plateau phase in the beginning, a rapid decline and a further plateau at treatment end. By modeling the dynamic speed of response with fMRI-data, perigenual anterior cingulate activity after treatment was significantly associated with antidepressant response (p < 0.001, FWE-corrected). Temporoparietal junction (TPJ) baseline activity significantly predicted non-remission after 2 antidepressant trials (p = 0.005, FWE-corrected). The results underline the importance of the medial thalamus, attention networks in MD and antidepressant treatment. Moreover, by using a sigmoid model, this study provides a novel method to analyze the dynamic nature of response and remission for future trials

Coercive and legitimate authority impact tax honesty:Evidence from behavioral and ERP experiments

Cooperation in social systems such as tax honesty is of central importance in our modern societies. However, we know little about cognitive and neural processes driving decisions to evade or pay taxes. This study focuses on the impact of perceived tax authority and examines the mental chronometry mirrored in ERP data allowing a deeper understanding about why humans cooperate in tax systems. We experimentally manipulated coercive and legitimate authority and studied its impact on cooperation and underlying cognitive (experiment 1, 2) and neuronal (experiment 2) processes. Experiment 1 showed that in a condition of coercive authority, tax payments are lower, decisions are faster and participants report more rational reasoning and enforced compliance, however, less voluntary cooperation than in a condition of legitimate authority. Experiment 2 confirmed most results, but did not find a difference in payments or self-reported rational reasoning. Moreover, legitimate authority led to heightened cognitive control (expressed by increased MFN amplitudes) and disrupted attention processing (expressed by decreased P300 amplitudes) compared to coercive authority. To conclude, the neuronal data surprisingly revealed that legitimate authority may led to higher decision conflict and thus to higher cognitive demands in tax decisions than coercive authority.Austrian Science Fund (FWF) [24863-G1]; Austrian Economic Chamber (WKO)SCI(E)SSCIARTICLE71108-11171