No description available.

No description available.

No description available.

We often form intentions but have to postpone them until the appropriate situation for retrieval and execution has come, an ability also referred to as event-based prospective memory. After intention completion, our cognitive system has to deactivate no-more-relevant intention representations from memory to avoid interference with subsequent tasks. In everyday life, we frequently rely on these abilities also in stressful situations. Surprisingly, little is known about potential stress effects on these functions. Therefore, the present study aimed to examine the reliability of event-based prospective memory and of intention deactivation in conditions of acute psychosocial stress. To this aim, eighty-two participants underwent the Trier Social Stress Test, a standardized stress protocol, or a standardized control situation. Following this treatment, participants performed a computerized event-based prospective memory task with non-salient and focal prospective memory cues in order to assess prospective memory performance and deactivation of completed intentions. Although the stress group showed elevated levels of salivary cortisol as marker of a stress-related increase in hypothalamus-pituitary-adrenal axis activity throughout the cognitive testing period compared to the no-stress group, prospective memory performance and deactivation of completed intentions did not differ between groups. Findings indicate that cognitive control processes subserving intention retrieval and deactivation after completion may be mostly preserved even under conditions of acute stress.

Eine phasische Ausschüttung des Neurotransmitters Dopamin wird u.a. mit positivem Affekt, der Reaktivität auf Neuheit und kognitiver Handlungssteuerung in Verbindung gebracht. In der vorliegenden Doktorarbeit wurde der dopaminerge Einfluss auf die Flexibilität und Stabilität der Handlungssteuerung untersucht. Für eine zielgerichtete Handlung sind beide antagonistischen Anforderungen notwendig. Einerseits müssen gewählte Handlungsabsichten gegenüber irrelevanten Ablenkungsreizen abgeschirmt und somit stabilisiert werden. Andererseits müssen diese Absichten im Falle handlungsrelevanter Änderungen der Situation flexibel angepasst werden. Als theoretische Grundlage für die vorliegende Arbeit dienten in diesem Zusammenhang folgende Kernthesen von Miller und Cohen (2001): (1) Der präfrontale Kortex (PFC) ist entscheidend an der Regulation der Handlungssteuerung beteiligt. (2) Eine phasische Dopaminausschüttung ermöglicht die Aufnahme neuer Reize im PFC und damit die Möglichkeit, gegebenenfalls aktuelle Regeln und Ziele zu ändern. (3) Eine phasische Dopaminausschüttung verschiebt demnach die Balance zwischen einer flexiblen und stabilen Handlungssteuerung in Richtung Flexibilität. In den ersten beiden Studien der vorliegenden Arbeit wurde der Einfluss interindividueller Unterschiede dopaminerger Aktivität auf die Flexibilität der Handlungssteuerung untersucht. Als Prädiktoren wurden die spontane Lidschlagrate (EBR), die Polymorphismen COMT Val-158-Met und DRD4 Exon III sowie das Geschlecht eingesetzt. In der dritten Studie sollte eine Dopaminausschüttung experimentell durch die Darbietung von Signalen einer potenziellen Belohnung (Geldgewinn) stimuliert werden. Hierdurch sollten die beobachteten Zusammenhänge aus den ersten beiden Studien erhärtet und in einem erweiterten theoretischen Kontext untersucht werden. In allen drei Studien zeigte sich ein signifikanter Zusammenhang von Lidschlagrate und kognitiver Flexibilität (mittleres η²=8%). Entsprechend der Vorhersage wurde mit steigender Lidschlagrate eine erhöhte Flexibilität beobachtet. Ferner ergaben sich Interaktionseffekte zwischen EBR und DRD 4 Exon III Polymorphismus bzw. EBR und Geschlecht, sowie ein Geschlechtshaupteffekt. Zur Stabilität dieser Effekte konnte jedoch jeweils keine abschließende Aussage gemacht werden. In der dritten Studie zeigte sich bei Darbietung des Belohnungssignals eine erhöhte kognitive Stabilität (η²=7%). Dieser Zusammenhang wurde vom subjektiven Erlebens des Experiments moderiert (η²=11%): Personen, die den Eindruck hatten, ohne große Anstrengung viel zu gewinnen, zeigten eine erhöhte kognitive Flexibilität. Diese beiden Befunde können innerhalb einer integrativen Theorie von Cohen et al. (2004) plausibel erklärt werden. Der Belohnungs-Haupteffekt könnte auf die Dominanz eines (noradrenergen) Wirkungspfades im Kontext der Wettkampfsituation hinweisen. Der moderierende Effekt des subjektiven Erlebens könnte gemäß der oben erläuterten Kernthesen von Miller und Cohen (2001) als gleichzeitige Flexibilisierung über den dopaminergen Wirkungspfad interpretiert werden, die insbesondere bei geringer wahrgenommener Anstrengung dominieren kann. Als wichtigstes Ergebnis der vorliegenden Arbeit kann zusammenfassend festgestellt werden, dass die Hypothese einer dopaminergen Beeinflussung der Flexibilitäts-Stabilitäts-Balance der kognitiven Handlungssteuerung durch die Ergebnisse der drei Studien unterstützt werden konnte. Dabei erwies sich insbesondere die spontane Lidschlagrate als zuverlässiger non-invasiver und effizient zu erhebender Prädiktor dopaminerger Aktivität. Der flexibilisierende Einfluss von Dopamin kann von einem stabilisierenden Einfluss überlagert werden. Dies ist insbesondere dann der Fall, wenn eine erforderliche Leistung zur Erreichung einer Belohnung als nützlich eingeschätzt und subjektiv als anstrengend wahrgenommen wird. / Converging evidence suggests a modulatory role of the neurotransmitter dopamine concerning reward, positive affect, novelty, and cognitive control. According to Miller and Cohen (2001) a phasic burst of dopamine shifts the balance between cognitive flexibility versus stability towards increased flexibility. Based on this assumption the current dissertation aimed at revealing associations between correlates of dopaminergic activity and the cognitive flexibility in an attentional set-shifting paradigm. In the first two studies we examined individual differences in the spontaneous eyeblink rate (EBR), the polymorphisms DRD4 exon III and COMT Val158Met polymorphism, as well as gender. In the third study we examined the impact of prospective monetary gains. Through this the findings of the first two studies should be validated and tested in an extended theoretical background. In all three studies an association between high EBR and increased cognitive flexibility was observed (mean η²=8%). Thus the main thesis of Miller and Cohen (2001) could be confirmed. Furthermore we observed interactions between EBR and DRD4 and EBR and gender, as well as a gender main effect on cognitive flexibility. In the third study we observed increased cognitive stability in the face of prospective gains (η²=7%). However, this effect was modulated by the subjective evaluation of the reward cues: participants who reported increasing their effort in response to reward cues showed increased cognitive stability whereas those who reported a positive and relaxed attitude towards the reward cues showed increased flexibility (η²=11%). The results thus suggest that the flexibility-stability-balance is modulated by the perceived effort needed to receive the potential reward.

Pathologisches Glücksspiel (PG) ist eine psychiatrische Erkrankung, die gerade erst im DSM-5 der gleichen Kategorie wie substanzgebundene Suchterkrankungen zugeordnet wurde. Bildgebungsstudien zu Substanzabhängigkeit beobachteten funktionelle und strukturelle Veränderungen im präfrontalen Kortex (PFC) und mesolimbischen Belohnungssystem (d.h. Striatum). Für PG wurden ähnliche Veränderungen berichtet; jedoch gibt es kaum Studien, die sich mit verschiedenen Aspekten funktioneller und struktureller Korrelate in diesen Regionen beschäftigen. Diese Arbeit untersuchte PG Patienten, alkoholabhängige (AD) Patienten und Kontrollpersonen (HC) mit Magnetresonanztomografie. In Analyse I wurden funktionelle Gehirndaten während der Belohnungsaufgabe zwischen den drei Gruppen verglichen. In Analyse II wurde das Volumen grauer Substanz mit voxelbasierter Morphometrie und in Analyse III die intrinsische Gehirnaktivität mit einer seedbasierten funktionellen Konnektivitätsanalyse von PG Patienten und HC ausgewertet. Die Analysen ergaben veränderte Aktivierungen in frontostriatalen Arealen während der Verarbeitung von Verlustvermeidung für PG Patienten im Vergleich zu HC. PG Patienten unterschieden sich dabei in ihrer Aktivierung von AD Patienten während der Antizipation von Geldverlust. Weiterhin zeigten PG Patienten erhöhte Volumina grauer Substanz und eine erhöhte funktionelle Konnektivität in frontostriatalen Arealen im Vergleich zu HC. Die Ergebnisse liefern weitere Hinweise für eine veränderte Belohnungsverarbeitung in PG und betonen die Bedeutung der Verlustvermeidungsverarbeitung. Die Volumenveränderungen im und die erhöhte Konnektivität zwischen dem PFC and Belohnungssystem deuten auf eine veränderte Interaktion zwischen diesen Regionen hin. Da solche Veränderungen in kortikostriatalen Systemen Ähnlichkeiten zu denen in Substanzabhängigkeiten aufweisen, unterstützen die Ergebnisse die neue Klassifikation des PG im DSM-5. / Pathological gambling (PG) is a psychiatric disorder newly classified under the same category as substance use disorders in the DSM-5. Neuroimaging studies on substance-related addictions reported functional and structural changes in the prefrontal cortex (PFC) and the mesolimbic reward system (i.e., striatum). For PG, findings are not that extensive, but also demonstrate altered reward processing and prefrontal function. However, there is a lack of studies focusing on different aspects of functional and structural correlates within these areas in PG. This thesis investigated PG patients, alcohol dependent (AD) patients and healthy controls with magnetic resonance imaging (MRI). In analysis I, functional brain data of a reward paradigm was compared between the three groups. In analysis II, local gray matter volume of PG patients and controls was processed via voxel-based morphometry. Resting-state data of PG patients and controls was analyzed via seed-based functional connectivity in analysis III. Results revealed altered brain responses in fronto-striatal areas during loss avoidance processing in PG patients as compared to controls. Importantly, PG patients differed in their brain responses from AD patients during the prospect of monetary loss. Moreover, PG patients showed an increase in local gray matter volume and functional connectivity in frontal-striatal areas as compared to controls. Our results add further evidence for an altered reward processing in PG and underline the importance of loss avoidance processing. Moreover, our findings of volumetric alterations within and increased connectivity between PFC and reward system, suggest an altered interaction between these brain regions. Since such alterations in cortico-striatal circuits resemble those reported for substance-related addictions, our findings support the new classification of PG in the DSM-5.

Theory of Mind (ToM) is the ability to infer others’ mental states and thus to predict their behavior (Perner, 1991). Therefore, ToM is essential for the adequate adjustment of behavior in social situations. ToM can be divided into: 1) cognitive ToM encompassing inferences about intentions and beliefs and 2) affective ToM encompassing inferences about emotions (Shamay-Tsoory, Harari, Aharon-Peretz, & Levkovitz, 2010). Well-functioning skills of both ToM aspects are much-needed in the developmental period of adolescence because in this age phase peer relationships become more important and romantic relationships arise (Steinberg & Morris, 2001). Importantly, affective psychopathological disorders often have their onset in adolescence. ToM development in adolescence might be based on underlying cognitive mechanisms such as the ability to inhibit one’s own thoughts in order to understand another person’s thoughts (Carlson & Moses, 2001). Another possible mechanism relates to functional brain development across adolescence (Blakemore, 2008). Therefore, neurocognitive mechanisms may underlie ongoing ToM development in adolescence. First studies indicate an ongoing behavioral and functional brain development of ToM (e.g. Blakemore, 2008). However, ToM development in adolescence and how this might relate to underlying (neuro)cognitive functions remains largely underexamined. The major aims of the current thesis were first to answer the overall question whether there is an ongoing development of ToM in adolescence. This question relates to both behavioral and functional brain development. As a second major aim, the present work sought to elucidate possible (neuro)cognitive mechanisms of ongoing ToM development across adolescence. Specifically, these cognitive mechanisms might be basic cognitive functions as well as executive functions. Additionally, the present work aimed at exploring potential (neuro)cognitive mechanisms through an integration of both behavioral and functional brain studies. The current experimental work spans three cross-sectional studies investigating adolescents (aged around 12-15 years) and young adults (aged around 18-22 years) to examine for the first time both the behavioral (studies I and II) and functional brain development of ToM (study III) in adolescence and its underlying (neuro)cognitive mechanisms. In all three studies, more complex, advanced ToM tasks were employed to avoid ceiling effects. Study I was aimed at investigating if cognitive and affective ToM continues to develop in adolescence and at exploring if basic cognitive variables such as verbal ability, speed of processing, and working memory capacity underlie such development. Hence, two groups of adolescents and young adults completed tasks of ToM and basic cognitive abilities. Large age effects were revealed on both measures of ToM: adolescents performed lower than adults. These age differences remained significant after controlling for basic cognitive variables. However, verbal ability covaried with performance in affective ToM. Overall, results support the hypothesis of an ongoing development of ToM from adolescence to adulthood on both cognitive and affective aspects. Results may further indicate verbal ability being a basic cognitive mechanism of affective ToM. Study II was designed to further explore if affective ToM, as measured with a dynamic realistic task, continues to develop across adolescence. Importantly, this study sought to explore executive functions as higher cognitive mechanisms of developing affective ToM across adolescence. A large group spanning adolescents and young adults evaluated affective mental states depicted by actors in video clips. Additionally, participants were examined with three subcomponents of executive functions, inhibition, updating, and shifting following the classification of Miyake et al. (2000). Affective ToM performance was positively related to age and all three executive functions. Specifically, inhibition explained the largest amount of variance in age related differences of affective ToM performance. Overall, these results indicate the importance of inhibition as key underlying mechanism of developing an advanced affective ToM in adolescence. Study III set out to explore the functional brain development of affective ToM in adolescence by using functional magnetic resonance imaging (fMRI). The affective ToM measure was the behavioral developmentally sensitive task from study II. An additional control condition consisted of the same emotional stimuli with the instruction to focus on physical information. This study faced methodical challenges of developmental fMRI studies by matching performance of groups. The ventromedial prefrontal cortex (vMPFC) was significantly less deactivated in adolescents in comparison to adults, which might suggest that adolescents seem to rely more on self-referential processes for affective ToM. Furthermore, adolescents compared to adults showed greater activation in the dorsolateral prefrontal cortex (DLPFC) in the control condition, indicating that adolescents might be distracted by the emotional content and therefore needed to focus more on the physical content of the stimulus. These findings suggest affective ToM continues to develop on the functional brain level and reveals different underlying neurocognitive strategies for adolescents in contrast to adults. In summary, the current thesis investigated whether ToM continues to develop in adolescence until young adulthood and explored underlying (neuro)cognitive mechanisms. Findings suggest that there is indeed an ongoing development of both the cognitive and affective aspect of ToM, which importantly contributes to the conceptual debate. Moreover, the second benefit to the debate is to demonstrate how this change may occur. As a basic cognitive mechanism verbal ability and as an executive functioning mechanism inhibition was revealed. Furthermore, neurocognitive mechanisms in form of different underlying neurocognitive strategies of adolescents compared to adults were shown. Taken together, ToM development in adolescence seems to mirror a different adaptive cognitive style in adolescence (Crone & Dahl, 2012). This seems to be important for solving the wealth of socio-emotional developmental tasks that are relevant for this age span.

No description available.

We often form intentions but have to postpone them until the appropriate situation for retrieval and execution has come, an ability also referred to as event-based prospective memory. After intention completion, our cognitive system has to deactivate no-more-relevant intention representations from memory to avoid interference with subsequent tasks. In everyday life, we frequently rely on these abilities also in stressful situations. Surprisingly, little is known about potential stress effects on these functions. Therefore, the present study aimed to examine the reliability of event-based prospective memory and of intention deactivation in conditions of acute psychosocial stress. To this aim, eighty-two participants underwent the Trier Social Stress Test, a standardized stress protocol, or a standardized control situation. Following this treatment, participants performed a computerized event-based prospective memory task with non-salient and focal prospective memory cues in order to assess prospective memory performance and deactivation of completed intentions. Although the stress group showed elevated levels of salivary cortisol as marker of a stress-related increase in hypothalamus-pituitary-adrenal axis activity throughout the cognitive testing period compared to the no-stress group, prospective memory performance and deactivation of completed intentions did not differ between groups. Findings indicate that cognitive control processes subserving intention retrieval and deactivation after completion may be mostly preserved even under conditions of acute stress.

Bisherige Studien liefern Hinweise für das Auftreten von aktiven Prozessen der Reihenfolgekoordination in Doppelaufgaben. Diese Prozesse sind notwendig für die Regulation der Bearbeitungsreihenfolge von zwei Aufgaben. Bisher ist jedoch wenig über die kognitiven und neuronalen Mechanismen bekannt, die diesen Prozessen zugrunde liegen. Ziel der vorliegenden Dissertation war deshalb die Überprüfung eines Modells aktiver Reihenfolgekoordination in Doppelaufgaben. Das Modell nimmt an, dass diese Prozesse auf Repräsentationen zurückgreifen, die Informationen über die Verarbeitungssequenz zweier Aufgaben enthält. Zusätzlich macht das Modell Annahmen über (1) den Ort der Verarbeitung und (2) den genauen Inhalt dieser Repräsentationen. Weiterhin enthält das Modell die Annahmen, dass (3) der präfrontale Kortex kausal in Reihenfolgekoordination involviert ist und dass (4) diese Prozesse von unterschiedlichen Kriterien beeinflusst werden. In dieser Dissertation wurde das Model in einer Reihe von vier Studien überprüft. Dazu wurde ein Doppelaufgabenparadigma mit zufällig wechselnder Aufgabenreihenfolge verwendet. Ich konnte zeigen, dass die Reihenfolgerepräsentationen im Arbeitsgedächtnis aufrechterhalten und aktiv verarbeitet werden. Ich konnte weiterhin zeigen, dass diese Repräsentationen nur Information über die Sequenz der Aufgaben enthalten. Spezifische Aufgabeninformation wird hingegen separat repräsentiert. Durch den Einsatz transkranieller Magnetstimulation konnte ich zudem nachweisen, dass der präfrontale Kortex eine kausale Rolle für Reihenfolgekoordination spielt. Darüber hinaus konnte ich zeigen, dass Anforderungen an Reihenfolgekoordinationsprozesse in Situationen, in denen Probanden ein von außen vorgegebenes Reihenfolgekriterium befolgen, erhöht sind im Vergleich zu Situationen, in denen Probanden ein auf einer freien Wahl basierendes Kriterium nutzen können. Die Implikationen dieser Ergebnisse werden unter Berücksichtigung des vorgeschlagenen Modells diskutiert. / Evidence from behavioral as well as neurophysiological studies indicates the occurrence of active task-order coordination processes in dual-task situations. These processes are required for planning and regulating the processing sequence of two tasks that overlap in time. So far, however, the cognitive and neural mechanisms underlying active task-order coordination are highly underspecified. To tackle this issue, in the present dissertation I tested a model of task-order coordination in dual-task situations. This model assumes that task-order coordination relies on representations that contain information about the processing sequence of the two component tasks. In addition, the model includes assumptions about the (1) locus of processing as well as (2) the exact content of these order representations. The model further assumes that (3) the lateral prefrontal cortex is causally involved in implementing task-order coordination processes and that (4) these processes are affected by different order criteria. I tested this model in a series of four studies by applying a dual-task paradigm with randomly changing task order. I demonstrated that task-order representations are actively maintained and processed in working memory during dual tasking. Moreover, I found that these order representations only contain information about the processing sequence of tasks, whereas specific component task information is represented separately. By applying transcranial magnetic stimulation, I also provided evidence for the causal role of the lateral prefrontal cortex for task-order coordination. Furthermore, I showed that the demands on task-order coordination are increased when participants have to adhere to an external and mandatory order criterion compared to when they can use an internally generated order criterion that is based on free choice. The implications of these results as well as an outlook for future research will be discussed in the framework of the proposed model.