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Multimodal study of decision-making and metacognitive processes in Obsessive-Compulsive Disorders: role of the anteromedial subthalamic nucleus

on the November 17, 2023

PhD defense of Audrey Kist

On Friday November 17th 2023, Audrey KIST will defend her thesis "Multimodal study of decision-making and metacognitive processes in Obsessive-Compulsive Disorders: role of the anteromedial subthalamic nucleus".

This thesis has been directed by Mircea POLOSAN of the Psychiatry service of the CHUGA, Nathan FAIVRE of the LPNC et Julien BASTIN of the "Brain, Behavior and Neuromodulation" team of the GIN.

Jury members :

  • 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
  • Vincent de Gardelle, CNRS Délégation Paris Centre, Examinateur
  • Brigitte Piallat, Université Grenoble Alpes, Examinatrice
  • Pr Christopher MOULIN, Université Grenoble Alpes, Examinateur
  • Julien BASTIN, Inserm - Grenoble Institut Neurosciences, Invité
  • Nathan FAIVRE, CNRS Délégation Alpes - LPNC, Invité

Abstract :

What happens in our brain when we decide? Whether it is detecting the presence or absence of danger in our field of vision (perceptual decision), or choosing an apartment based on our needs (multi-attribute decision), one explanatory hypothesis is that our choices are based on information we gather from our environment and accumulate. When this accumulated information is deemed sufficient and reaches a threshold, which can be modulated, for example, by our emotional state, then we are able to comit to a decision, the quality of which we can evaluate by issuing a confidence judgment. While the role of the cortex in decision-making is well-documented, the same cannot be said for subcortical structures, particularly the subthalamic nucleus (STN). However, various clues suggest that this nucleus may play a modulatory role in the decision threshold and mood. The purpose of this thesis is to document this potential role.

We took advantage of a clinical trial of deep brain stimulation (DBS) of the anteromedial subthalamic nucleus (amSTN) in the treatment of obsessive-compulsive disorder (OCD) to conduct four experimental studies. The first two studies focus on perceptual decision-making. In Study 1, through local field potential (LFP) recordings in eight patients with OCD, we show that oscillatory activity in the amSTN in the alpha and beta bands is linked to detection and confidence reports. Study 2, using EEG in participants with OCD with or without STN stimulation, demonstrates that stimulation preserves detection and confidence reports and reveals a metacognitive deficit in patients. The following two studies concern multi-attribute decision-making. LFPs collected from ten participants with OCD in Study 3 teach us that theta oscillations in the amSTN reflect choice attributes, mood reports, and choice outcomes but not confidence judgments. Study 4, a behavioral study in participants with OCD with or without amSTN stimulation, shows that stimulation modulates multi-attribute decision-making, confidence judgments, and mood.

All of these studies provide insights into the involvement of the STN in decision-making and metacognitive processes. They expand our understanding of this structure by exploring a relatively uncharted territory within the amSTN, which is associated with associative and limbic processes.

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