Thesis defense Miles Wischnewski (Donders sereis 358)

30 January 2019

Promotor: prof. dr. H. Bekkering, co-promotor: dr. D. Schutter

Interfering with feedback processing: Implications for decision making and learning

When making decisions in uncertain situations, people tend to rely on any information they can grasp. This information could come from feedback, context or advice. Yet, how such information affects the brain processes involved in decision making is not completely understood. In the first experiment described in this thesis it was found that brain areas compute rewards and punishments both in a context-dependent and context-independent. Furthermore, it was found that this happens relatively early during feedback processing, after approximately 200 milliseconds. In the following four chapters, experiments investigating the effects of advice taking are described. It was found that event-related potentials, such as the feedback-related negativity and the P200, as well as theta oscillations in frontal cortex reflect different validity values of advice cues. Based on these results the aim was to manipulate decision making behavior by targeting these brain processes by means of applying transcranial direct or alternating current stimulation. Whereas brain stimulation did not affect advice following behavior, in a set of two experiments it was found that transcranial alternating current stimulation can improve different aspects of reversal learning depending on the applied stimulation frequency. Since non-invasive brain stimulation may have potential as a clinical tool the long-term effects of such stimulation were explored in the last chapter. Altogether this thesis contributed to elucidate on the effects our surroundings have on the decisions we make every day.