Deutsche Übersetzung des Titels: Neuronale Korrelate interindividueller Variabilität bei Ziel-gerichtetem Verhalten

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Abstract

Goal-directed behaviour is an instrumental action performed to control our environment in order to provide a satisfactory outcome. It has been shown that these actions do not solely depend on action-outcome contingencies, but are also strongly influenced by personality traits or psychiatric disorders. Personality aspects such as sensitivity to rewards and impulsivity, as well as schizophrenia, have been identified as prominent factors, though the exact relation still remains unclear. Therefore, the goal of this dissertation is to provide an additional specification of interindividual differences in goal-directed behaviour on a neural level. Using functional imaging, we employed 2 different paradigms to probe reward-related as well as inhibition-related neural activation in healthy subjects and patients with schizophrenia. Study I investigated the neural response during a monetary incentive delay task in 23 healthy subjects, relating the observed activations with psychometric assessed traits of behavioural approach/inhibition. We found that the tendency to approach reward-related situations leads to an elevated neural response to positive outcomes, and an attenuated response to omissions. Additionally, a high behavioural inhibition tendency led to an attenuated response to rewards. Study II applied the monetary incentive delay task on a group of 15 patients with schizophrenia, demonstrating a negative relation between striatal activation during the expectation of reward and the symptom of apathy, as well as negative relation between orbitofrontal activation during the receipt of a reward and the symptom of depression. Study III investigated the relation between the personality trait of impulsivity and brain activation during the inhibition of inappropriate responses. Results showed that impulsivity is positively related to activations of bilateral ventroprefrontal regions. The results illustrate the importance of frontal-subcortical networks in goal-directed behaviour in clinical and non-clinical populations. An orbitofrontal/striatal network is specifically related to behavioural approach and inhibition tendencies, whereas impairments in the ventral striatum can lead to symptoms of apathy and depression in patients with schizophrenia. Additionally, activity in ventrolateral prefrontal regions is related to motor inhibition during successful inhibition of unwanted responses. Providing exact definitions of the specific functions and dependencies of frontal-subcortical circuits can inform our understanding of cognitive and emotional functions, and support research dealing with psychiatric disorders.

Übersetzung des Abstracts (Deutsch)

Das Ziel der vorliegenden Dissertation ist die genaue Erfassung der Zusammenhänge zwischen verschiedenen Persöhnlichkeitseigenschaften und den neuronalen Grundlagen Ziel-gerichteten Verhaltens. Zwei unterschiedliche experimentelle Paradigmen wurden benutzt um mittels funktioneller Magnetresonanztomographie 3 Studien durchzuführen. Studie 1 rekrutierte 23 gesunde Probanden und erfasste den Zusammenhang zwischen belohnungsrelevanter neuronaler Verarbeitungsprozesse und der Persöhnlichkeitseigenschaft „Sensitivität für Belohnung“, Studie 2 rekrutierte 15 gesunde Probanden sowie 15 Patienten mit Schizophrenie und erfasste Zusammenhänge zwischen schizophrener Symptomatik und belohnungsrelevanter neuronaler Verarbeitungsprozesse. Studie 3 erfasste den Zusammenhang zwischen der Persöhnlichkeitseigenschaft „Impulsivität“ und der neuronalen Grundlage der Inhibition unangemessener Reaktionen. Die Resultate der Studien weisen auf die Bedeutung frontal-subkortikaler Netzwerke in Ziel-gerichtetem Verhalten bei gesunden und klinischen Gruppen hin.