Thesis defence : Audrey KIST

What happens in our brains when we make a decision? Whether we are detecting the presence or absence of a danger in our field of vision (a perceptual decision), or choosing a flat according to our needs (a multi-attribute decision), one hypothesis is that our choices are based in particular on information that we collect in our environment and that we accumulate. When this accumulated information is judged to be sufficient and reaches a threshold, which can be modulated by our emotional state for example, then we are in a position to make a decision, the quality of which we can assess by making a judgment of confidence. While the role of the cortex in decision making is well documented, the same cannot be said for subcortical structures, and in particular the subthalamic nucleus (STN). However, there is evidence that this nucleus appears to play a modulatory role in decision threshold and mood. The aim of this thesis is to document this possible role.

We took the opportunity of a clinical trial of deep brain stimulation (DBS) of the anteromedial subthalamic nucleus (AMSTN) in the treatment of obsessive-compulsive disorder (OCD) to carry out four experimental studies. The first two studies focused on perceptual decision making. In Study 1, using local field potential (LFP) recordings from eight patients with OCD, we show that the oscillatory activity of the NST in the alpha and beta bands is related to detection and confidence ratios. Study 2 on electroencephalography (EEG) in participants with OCD with or without NST stimulation shows that stimulation preserves detection and confidence ratios and highlights a metacognitive deficit in the patients. The next two studies focused on multi-attribute decision making. The LFPs collected from ten participants with OCD in Study 3 show that theta oscillations of the NSTam reflect choice attributes, mood reports and outcome, but not confidence judgements. Study 4, a behavioural study involving participants with OCD with or without stimulation of the NSTam, shows that stimulation modulates the multi-attribute decision, confidence judgements and mood.

Taken together, these studies provide information about the involvement of the NTS in decision-making and metacognitive processes. It completes our knowledge of this structure by focusing on an area of the NST that has been little explored until now: the anteromedial part, which relates to associative and limbic processes.

Pr Mircea Polosan, Université Grenoble Alpes, Directeur de thèse

Pre Marie-Laure WELTER, Université de Rouen Normandie, Rapporteure 

Pr Paul SAULEAU, Université de Rennes, Rapporteur

 

- Directeur de thèse : Mircea POLOSAN

- Co-directeur : Nathan FAIVRE

- Co-directeur : Julien BASTIN