Oliver M. Hager
University of Zurich
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Featured researches published by Oliver M. Hager.
Behavioural Processes | 2013
Matthias Hartmann; Oliver M. Hager; Philippe N. Tobler; Stefan Kaiser
When humans and other animals make decisions in their natural environments prospective rewards have to be weighed against costs. It is well established that increasing costs lead to devaluation or discounting of reward. While our knowledge about discount functions for time and probability costs is quite advanced, little is known about how physical effort discounts reward. In the present study we compared three different models in a binary choice task in which human participants had to squeeze a handgrip to earn monetary rewards: a linear, a hyperbolic, and a parabolic model. On the group as well as the individual level, the concave parabolic model explained most variance of the choice data, thus contrasting with the typical hyperbolic discounting of reward value by delay. Research on effort discounting is not only important to basic science but also holds the potential to quantify aberrant motivational states in neuropsychiatric disorders.
BMC Psychiatry | 2016
Martin Bischof; Caitriona Obermann; Matthias Hartmann; Oliver M. Hager; Matthias Kirschner; Agne Kluge; Gregory P. Strauss; Stefan Kaiser
BackgroundNegative symptoms are considered core symptoms of schizophrenia. The Brief Negative Symptom Scale (BNSS) was developed to measure this symptomatic dimension according to a current consensus definition. The present study examined the psychometric properties of the German version of the BNSS. To expand former findings on convergent validity, we employed the Temporal Experience Pleasure Scale (TEPS), a hedonic self-report that distinguishes between consummatory and anticipatory pleasure. Additionally, we addressed convergent validity with observer-rated assessment of apathy with the Apathy Evaluation Scale (AES), which was completed by the patient’s primary nurse.MethodsData were collected from 75 in- and outpatients from the Psychiatric Hospital, University Zurich diagnosed with either schizophrenia or schizoaffective disorder. We assessed convergent and discriminant validity, internal consistency and inter-rater reliability.ResultsWe largely replicated the findings of the original version showing good psychometric properties of the BNSS. In addition, the primary nurses evaluation correlated moderately with interview-based clinician rating. BNSS anhedonia items showed good convergent validity with the TEPS.ConclusionsOverall, the German BNSS shows good psychometric properties comparable to the original English version. Convergent validity extends beyond interview-based assessments of negative symptoms to self-rated anhedonia and observer-rated apathy.
Schizophrenia Research | 2015
Matthias N. Hartmann-Riemer; Oliver M. Hager; Matthias Kirschner; Martin Bischof; Agne Kluge; Erich Seifritz; Stefan Kaiser
Negative symptoms can be grouped into the two dimensions of diminished expression and apathy, which have been shown to be dissociable regarding external validators, such as functional outcome. Here, we investigated whether these two dimensions differentially relate to neurocognitive impairment in schizophrenia. 47 patients with schizophrenia or schizoaffective disorder and 33 healthy control participants were subjected to a neurocognitive test battery assessing multiple cognitive domains (processing speed, working memory, verbal fluency, verbal learning and memory, mental planning), which are integrated into a composite cognition score. Negative symptoms in patients were assessed using the Brief Negative Symptom Scale. We found that diminished expression significantly related to neurocognitive impairment, while severity of apathy symptoms was not directly associated with neurocognition. Other assessed clinical variables include chlorpromazine equivalents, positive symptoms, and depressive symptoms and did not influence the results. Our results are in line with a cognitive resource limitation model of diminished expression in schizophrenia and indicate that cognitive remediation therapy might be helpful to ameliorate expressive deficits.
Kirschner, Matthias; Hager, Oliver M; Bischof, Martin; Hartmann-Riemer, Matthias N; Kluge, Agne; Seifritz, Erich; Tobler, Philippe N; Kaiser, Stefan (2016). Deficits in context-dependent adaptive coding of reward in schizophrenia. npj Schizophrenia, 2:16020. | 2016
Matthias Kirschner; Oliver M. Hager; Martin Bischof; Matthias N. Hartmann-Riemer; Agne Kluge; Erich Seifritz; Philippe N. Tobler; Stefan Kaiser
Theoretical principles of information processing and empirical findings suggest that to efficiently represent all possible rewards in the natural environment, reward-sensitive neurons have to adapt their coding range dynamically to the current reward context. Adaptation ensures that the reward system is most sensitive for the most likely rewards, enabling the system to efficiently represent a potentially infinite range of reward information. A deficit in neural adaptation would prevent precise representation of rewards and could have detrimental effects for an organism’s ability to optimally engage with its environment. In schizophrenia, reward processing is known to be impaired and has been linked to different symptom dimensions. However, despite the fundamental significance of coding reward adaptively, no study has elucidated whether adaptive reward processing is impaired in schizophrenia. We therefore studied patients with schizophrenia (n=27) and healthy controls (n=25), using functional magnetic resonance imaging in combination with a variant of the monetary incentive delay task. Compared with healthy controls, patients with schizophrenia showed less efficient neural adaptation to the current reward context, which leads to imprecise neural representation of reward. Importantly, the deficit correlated with total symptom severity. Our results suggest that some of the deficits in reward processing in schizophrenia might be due to inefficient neural adaptation to the current reward context. Furthermore, because adaptive coding is a ubiquitous feature of the brain, we believe that our findings provide an avenue in defining a general impairment in neural information processing underlying this debilitating disorder.
Schizophrenia Research | 2015
Oliver M. Hager; Matthias Kirschner; Martin Bischof; Matthias N. Hartmann-Riemer; Agne Kluge; Erich Seifritz; Philippe N. Tobler; Stefan Kaiser
The negative symptoms of schizophrenia have been associated with altered neural activity during both reward processing and cognitive processing. Even though increasing evidence suggests a strong interaction between these two domains, it has not been studied in relation to negative symptoms. To elucidate neural mechanisms of the reward-cognition interaction, we applied a letter variant of the n-back working memory task and varied the financial incentives for performance. In the interaction contrast, we found a significantly activated cluster in the rostral anterior cingulate cortex (ACC), the middle frontal gyrus, and the bilateral superior frontal gyrus. The interaction did not differ significantly between the patient group and a healthy control group, suggesting that patients with schizophrenia are on average able to integrate reward information and utilize this information to maximize cognitive performance. However within the patient group, we found a significant inverse correlation of ACC activity with the factor diminished expression. This finding is consistent with the model that a lack of available cognitive resources leads to diminished expression. We therefore argue that patients with diminished expression have difficulties in recruiting additional cognitive resources (as implemented in the ACC) in response to an anticipated reward. Due to this lack of cognitive resources, less processing capacity is available for effective expression, resulting in diminished expressive behavior.
Schizophrenia Bulletin | 2016
Matthias Kirschner; Oliver M. Hager; Larissa Muff; Martin Bischof; Matthias N. Hartmann-Riemer; Agne Kluge; Benedikt Habermeyer; Erich Seifritz; Philippe N. Tobler; Stefan Kaiser
Striatal abnormalities play a crucial role in the pathophysiology of schizophrenia. Growing evidence suggests an association between aberrant striatal activity during reward anticipation and symptom dimensions in schizophrenia. However, it is not clear whether this holds across the psychosis continuum. The aim of the present study was to investigate alterations of ventral striatal activation during reward anticipation and its relationship to symptom expression in persons with schizotypal personality traits (SPT) and first-episode psychosis. Twenty-six individuals with high SPT, 26 patients with non-affective first-episode psychosis (including 13 with brief psychotic disorder (FEP-BPD) and 13 with first-episode schizophrenia [FEP-SZ]) and 25 healthy controls underwent event-related functional magnetic resonance imaging while performing a variant of the Monetary Incentive Delay task. Ventral striatal activation was positively correlated with total symptom severity, in particular with levels of positive symptoms. This association was observed across the psychosis continuum and within each subgroup. Patients with FEP-SZ showed the strongest elevation of striatal activation during reward anticipation, although symptom levels did not differ between groups in the psychosis continuum. While our results provide evidence that variance in striatal activation is mainly explained by dimensional symptom expression, patients with schizophrenia show an additional dysregulation of striatal activation. Trans-diagnostic approaches are promising in order to disentangle dimensional and categorical neural mechanisms in the psychosis continuum.
Schizophrenia Research | 2017
Agne Kluge; Matthias Kirschner; Oliver M. Hager; Martin Bischof; Benedikt Habermeyer; Erich Seifritz; Sebastian Walther; Stefan Kaiser
BACKGROUND Apathy can be defined as a reduction of goal-directed behavior and is a strong predictor for poor functional outcome in schizophrenia. However, no objective measure of apathy has been identified and assessment is limited to retrospective interview-based ratings. Here we aimed to identify more precise objective readouts of apathy for translational research and clinical practice. METHODS We employed a combined approach including interview-based ratings of the two negative symptom factors apathy and diminished expression, actigraphy based measures of spontaneous motor activity and the evaluation of daily activities using ecological momentary assessment. Furthermore, a functional magnetic resonance imaging task for reward anticipation was applied to investigate shared and divergent neural correlates of interview-based and behaviorally measured apathy. RESULTS We found in 18 schizophrenia patients with high interview-based apathy levels that motor activity was negatively correlated with apathy but not with diminished expression. In contrast, measures of daily activities were not associated with apathy. Neural activation during reward anticipation revealed an association between hypoactivation of the ventral striatum and interview-based apathy as well as hypoactivation of the inferior frontal gyrus and motor activity level. CONCLUSIONS Spontaneous motor activity is an objective readout of apathy, which was specific and not present for diminished expression. On a neural level, interview-based and objective measures of apathy showed divergent neural correlates in the cortical-striatal network, which suggests dissociable neural processes. Finally, motor activity provides a promising readout for quantifying apathy in both translational research and clinical practice.
British Journal of Psychiatry Open | 2016
Aleksandra Kupferberg; Oliver M. Hager; Urs Fischbacher; Laura S. Brändle; Melanie Haynes; Gregor Hasler
Background Price’s social competition hypothesis interprets the depressive state as an unconscious, involuntary losing strategy, which enables individuals to yield and accept defeat in competitive situations. Aims We investigated whether patients who suffer from major depressive disorder (MDD) would avoid competition more often than either patients suffering from borderline personality disorder (BPD) or healthy controls. Method In a simple paper-folding task healthy participants and patiens with MDD and BPD were matched with two opponents, one with an unknown diagnosis and one who shared their clinical diagnosis, and they had to choose either a competitive or cooperative payment scheme for task completion. Results When playing against an unknown opponent, but not the opponent with the same diagnosis, the patients with depression chose the competitive payment scheme statistically less often than healthy controls and patients diagnosed with BPD. Conclusion The competition avoidance against the unknown opponent is consistent with Price’s social competition hypothesis. Declaration of interest G.H. received research support, consulting fees and speaker honoraria from Lundbeck, AstraZeneca, Servier, Eli Lilly, Roche and Novartis. Copyright and usage
Psychiatry Research-neuroimaging | 2016
Nora Preuss; Laura S. Brändle; Oliver M. Hager; Melanie Haynes; Urs Fischbacher; Gregor Hasler
Inconsistent social behavior is a core psychopathological feature of borderline personality disorder. The goal of the present study was to examine inconsistency in social decision-making using simple economic social experiments. We investigated the decisions of 17 female patients with BPD, 24 patients with major depressive disorder (MDD), and 36 healthy controls in three single shot economic experiments measuring trust, cooperation, and punishment. BPD severity was assessed using the Zanarini Rating Scale for BPD. Investments across identical one-shot trust and punishment games were significantly more inconsistent in BPD patients than in controls. Such inconsistencies were only found in the social risk conditions of the trust and punishment conditions but not in the non-social control conditions. MDD patients did not show such inconsistencies. Furthermore, social support was negatively correlated with inconsistent decision-making in the trust and punishment game, which underscores the clinical relevance of this finding.
Schizophrenia Bulletin | 2015
Matthias Hartmann; Oliver M. Hager; Anna V. Reimann; Justin R. Chumbley; Matthias Kirschner; Erich Seifritz; Philippe N. Tobler; Stefan Kaiser