Birgit Abler

Prediction error as a linear function of reward probability is coded in human nucleus accumbens

Reward probability has been shown to be coded by dopamine neurons in monkeys. Phasic neuronal activation not only increased linearly with reward probability upon expectation of reward, but also varied monotonically across the range of probabilities upon omission or receipt of rewards, therefore modeling discrepancies between expected and received rewards. Such a discrete coding of prediction error has been suggested to be one of the basic principles of learning. We used functional magnetic resonance imaging (fMRI) to show that the human dopamine system codes reward probability and prediction error in a similar way. We used a simple delayed incentive task with a discrete range of reward probabilities from 0%-100%. Activity in the nucleus accumbens of human subjects strongly resembled the phasic responses found in monkey neurons. First, during the expectation period of the task, the fMRI signal in the human nucleus accumbens (NAc) increased linearly with the probability of the reward. Second, during the outcome phase, activity in the NAc coded the prediction error as a linear function of reward probabilities. Third, we found that the Nac signal was correlated with individual differences in sensation seeking and novelty seeking, indicating a link between individual fMRI activation of the dopamine system in a probabilistic paradigm and personality traits previously suggested to be linked with reward processing. We therefore identify two different covariates that model activity in the Nac: specific properties of a psychological task and individual character traits.

Abnormal reward system activation in mania.

Transmission of reward signals is a function of dopamine, a neurotransmitter known to be involved in the mechanism of psychosis. Using functional magnetic resonance imaging (fMRI), we investigated how expectation and receipt of monetary rewards modulate brain activation in patients with bipolar mania and schizophrenia. We studied 12 acutely manic patients with a history of bipolar disorder, 12 patients with a current episode of schizoaffective disorder or schizophrenia and 12 healthy subjects. All patients were treated with dopamine antagonists at the time of the study. Subjects performed a delayed incentive paradigm with monetary reward in the scanner that allowed for investigating effects of expectation, receipt, and omission of rewards. Patients with schizophrenia and healthy control subjects showed the expected activation of dopaminergic brain areas, that is, ventral tegmentum activation upon expectation of monetary rewards and nucleus accumbens activation during receipt vs omission of rewards. In manic patients, however, we did not find a similar pattern of brain activation and the differential signal in the nucleus accumbens upon receipt vs omission of rewards was significantly lower compared to the healthy control subjects. Our findings provide evidence for abnormal function of the dopamine system during receipt or omission of expected rewards in bipolar disorder. These deficits in prediction error processing in acute mania may help to explain symptoms of disinhibition and abnormal goal pursuit regulation.

Emotion Regulation Questionnaire – Eine deutschsprachige Fassung des ERQ von Gross und John

Zusammenfassung. Eines der ersten validierten Instrumente zur wissenschaftlichen Untersuchung von Emotionsregulationsprozessen, stellt der englischsprachige Emotion Regulation Questionnaire (ERQ) von Gross und John (2003) dar. Dieser erlaubt es, Praferenzen fur zwei haufig angewandte Strategien zur Emotionsregulation, namlich Unterdruckung (suppression) und Neubewertung (reappraisal) zu erfassen. Die deutsche Version wurde in drei Ubersetzungsschritten an jeweils einer Gruppe von Studenten (n = 113/167/174) erprobt. Dabei stand eine moglichst enge Orientierung am englischen Original sowie die Optimierung der Faktoren-Ladungen auf die zwei Komponenten im Vordergrund. Eine Faktorenanalyse mit iterativer Kommunalitatenschatzung und Varimax-Rotation wurde verwendet. Entsprechend unserem Ziel erreichten die Alpha-Werte (innere Konsistenz) als Reliabilitatsmas fur Unterdruckung und Neubewertung die Durchschnittswerte des amerikanischen Originalfragebogens. Wir entwickelten ein Instrument, das einfach und in kur...

Neural correlates of frustration

Psychological considerations suggest that the omission of rewards in humans comprises two effects: first, an allocentric effect triggering learning and behavioural changes potentially processed by dopaminergic neurons according to the prediction error theory; second, an egocentric effect representing the individuals emotional reaction, commonly called frustration. We investigated this second effect in the context of omission of monetary reward with functional magnetic resonance imaging. As expected, the contrast omission relative to receipt of reward led to a decrease in ventral striatal activation consistent with prediction error theory. Increased activation for this contrast was found in areas previously related to emotional pain: the right anterior insula and the right ventral prefrontal cortex. We interpreted this as a neural correlate of the egocentric effect.

Motivating forces of human actions Neuroimaging reward and social interaction

In neuroeconomics, reward and social interaction are central concepts to understand what motivates human behaviour. Both concepts are investigated in humans using neuroimaging methods. In this paper, we provide an overview about these results and discuss their relevance for economic behaviour. For reward it has been shown that a system exists in humans that is involved in predicting rewards and thus guides behaviour, involving a circuit including the striatum, the orbitofrontal cortex and the amygdala. Recent studies on social interaction revealed a mentalizing system representing the mental states of others. A central part of this system is the medial prefrontal cortex, in particular the anterior paracingulate cortex. The reward as well as the mentalizing system is engaged in economic decision-making. We will discuss implications of this study for neuromarketing as well as general implications of these results that may help to provide deeper insights into the motivating forces of human behaviour.

Altered reward functions in patients on atypical antipsychotic medication in line with the revised dopamine hypothesis of schizophrenia

ObjectiveTo study the mesolimbic dopamine system during expectation and receipt or omission of rewards in partially remitted patients with schizophrenia treated with the atypical antipsychotic olanzapine.MethodsWe studied 16 patients with a current episode of schizophrenia, all treated with the atypical drug olanzapine, and 16 healthy subjects using functional magnetic resonance imaging. Subjects performed a delayed incentive paradigm with monetary rewards.ResultsDuring reward expectation, both, patients with schizophrenia and healthy control subjects, showed activation of the ventral striatum and midbrain in the vicinity of the ventral tegmental area. Significant categorical group differences emerged in the anterior cingulate cortex with only healthy controls showing increasing activation with increasing reward. In the patients, activation of this region was inversely correlated with positive symptoms. During outcome, both, patients with schizophrenia and healthy controls, showed activation of the ventral striatum and the mesial prefrontal cortex. Significant categorical group differences emerged in the right ventrolateral prefrontal cortex for the salience contrast with healthy controls showing a U-shaped activation curve, i.e., higher activation for either omission or receipt of reward compared to no reward.ConclusionsOur findings partially support the current concept of dopaminergic dysfunction in schizophrenia, suggesting a rather hyperactive mesolimbic dopamine system and reduced prefrontal activation, at least in partially remitted patients treated with atypical antipsychotics.

High Field fMRI Reveals Thalamocortical Integration of Segregated Cognitive and Emotional Processing in Mediodorsal and Intralaminar Thalamic Nuclei

Thalamocortical loops, connecting functionally segregated, higher order cortical regions, and basal ganglia, have been proposed not only for well described motor and sensory regions, but also for limbic and prefrontal areas relevant for affective and cognitive processes. These functions are, however, more specific to humans, rendering most invasive neuroanatomical approaches impossible and interspecies translations difficult. In contrast, non-invasive imaging of functional neuroanatomy using fMRI allows for the development of elaborate task paradigms capable of testing the specific functionalities proposed for these circuits. Until recently, spatial resolution largely limited the anatomical definition of functional clusters at the level of distinct thalamic nuclei. Since their anatomical distinction seems crucial not only for the segregation of cognitive and limbic loops but also for the detection of their functional interaction during cognitive–emotional integration, we applied high resolution fMRI on 7 Tesla. Using an event-related design, we could isolate thalamic effects for preceding attention as well as experience of erotic stimuli. We could demonstrate specific thalamic effects of general emotional arousal in mediodorsal nucleus and effects specific to preceding attention and expectancy in intralaminar centromedian/parafascicular complex. These thalamic effects were paralleled by specific coactivations in the head of caudate nucleus as well as segregated portions of rostral or caudal cingulate cortex and anterior insula supporting distinct thalamo–striato–cortical loops. In addition to predescribed effects of sexual arousal in hypothalamus and ventral striatum, high resolution fMRI could extent this network to paraventricular thalamus encompassing laterodorsal and parataenial nuclei. We could lend evidence to segregated subcortical loops which integrate cognitive and emotional aspects of basic human behavior such as sexual processing.

At-risk for pathological gambling: imaging neural reward processing under chronic dopamine agonists

Treatment with dopamine receptor agonists has been associated with impulse control disorders and pathological gambling (PG) secondary to medication in previously unaffected patients with Parkinsons disease or restless legs syndrome (RLS). In a within-subjects design, we investigated the underlying neurobiology in RLS patients using functional magnetic resonance imaging. We scanned 12 female RLS patients without a history of PG. All patients were scanned twice: once whilst taking their regular medication with low dose dopamine receptor agonists and once after a washout phase interval. They performed an established gambling game task involving expectation and receipt or omission of monetary rewards at different levels of probabilities. Upon expectation of rewards, reliable ventral striatal activation was detected only when patients were on, but not when patients were off medication. Upon receipt or omission of rewards, the observed ventral striatal signal under medication differed markedly from its predicted pattern which by contrast was apparent when patients were off medication. Orbitofrontal activation was not affected by medication. Chronic dopamine receptor agonist medication changed the neural signalling of reward expectation predisposing the dopaminergic reward system to mediate an increased appetitive drive. Even without manifest PG, chronic medication with dopamine receptor agonists led to markedly changed neural processing of negative consequences probably mediating dysfunctional learning of contingencies. Intact orbitofrontal functioning, potentially moderating impulse control, may explain why none of the patients actually developed PG. Our results support the notion of a general medication effect in patients under dopamine receptor agonists in terms of a sensitization towards impulse control disorders.

Cognitive reappraisal modulates expected value and prediction error encoding in the ventral striatum

In addiction, loss of prefrontal inhibitory control is believed to contribute to impulsivity. To improve cognitive therapy approaches, it is important to determine whether cognitive control strategies can generally influence reward processing at the neural level. We investigated the effects of one such strategy--namely, reappraisal (distancing from feelings)--on neural reward processing in 16 healthy subjects by utilizing event-related functional magnetic resonance imaging (fMRI). In a monetary incentive delay task, expected reward value (expecting to win 0.50 euro vs. 0.10 euro) and outcome valence (win vs. omission) were varied. An attenuation of expected value and a modulation of prediction error (PE) coding caused by distancing were found in right vs. left ventral striatum (VST) in the expectation vs. outcome period, respectively. Distancing from reward feelings recruited a right hemispheric fronto-parietal network. Moreover, self-reported reappraisal success (decrease of feelings by distancing) showed a trend toward positive correlation with activation in the rostral cingulate zone and the lateral orbitofrontal cortex, both part of the regulation network. Our results expand upon recent findings by showing that cognitive control over reward processing impacts not only the expectation period but also the reward signals in the outcome period. Moreover, increased recruitment of prefrontal reflective subsystems might enhance deliberate control over both reward processing and hedonic experience.

Neural Correlates of Error Monitoring Modulated by Atomoxetine in Healthy Volunteers

BACKGROUND Atomoxetine is a selective norepinephrine reuptake inhibitor clinically used for treatment of attention-deficit/hyperactivity disorder. In healthy control subjects, doses of 40 mg or 60 mg improved inhibitory control in combination with modulation of prefrontal cortex functioning. We investigated the effects of atomoxetine (80 mg) on error monitoring as a second key component of cognitive control. METHODS Twelve healthy, male volunteers were included in a randomized double-blind, placebo-controlled, within-subjects design to examine the effects of a single dose of atomoxetine on neural activities during a combined Eriksen flanker-Go/NoGo task as measured by functional magnetic resonance imaging. RESULTS Behaviorally, atomoxetine led to a significant increase in failed inhibition. Functionally, interaction analysis revealed a significant increase of the error signal (incorrect minus correct NoGo trials) under atomoxetine in bilateral inferior frontal cortex and presupplementary motor area. Drug-dependent increases in error signaling did not correlate with increased error rates. Analysis of neuropsychological data indexed a significant increase in phasic alertness. CONCLUSIONS Results support that atomoxetine increases neural sensitivity for errors in healthy control subjects, possibly due to an accentuated representation of the task set. However, this gain was accompanied by deterioration in inhibitory control, possibly reflecting a shift beyond the optimal working range of the norepinephrine system.