Cognitive flexibility can be described as adaptive ability to change one's behavior in response to the environment. Psychological tests measure cognitive flexibility mainly as an ability to switch between different cues, tasks or objects. This thesis is focused on cognitive flexibility in patients with obsessive compulsive disorder (OCD). To assess it, participants were tested in two different virtual tests of cognitive flexibility in spatial navigation task: Active allothetic place preference and Active allothetic place avoidance. In one of the tests participants have to navigate in rotating arena towads invisble goal (AAPP). In the other one they have to avoid invisible sector where time is counted upon entering (AAPA). As the sector and goal are visually imperceptible, participants have to use only cues inside and outside the arena and are also informed about entering the sector by sound signal. The sector changes its position from stable position in room frame to stable position in arena frame between conditions. Therefore, participants have to learn to switch between room and arena frame to sucessfully solve the task. Results of this study suggest that OCD patients are significantly worse in estimating position of the goal in AAPP, especially after change of condition. Further comparsion of...

The hippocampus plays a critical role in the detection of changes in familiar contexts. It accomplishes these functions through a continual process of comparing predicted features of a context or situation to those experienced. A mismatch between expected and experienced decision-making skills has been proven in previous studies that can be shown using the water maze, a test that is widely used to study spatial and working memory. Expectations are processed by specific neuronal networks, including the hippocampus and prefrontal cortex, to aid subsequent decision-making and response selection. Mice undergoing reversal learning in the water maze test must process the information relative to the new position of the escape platform and decide whether to navigate towards the latest or to the previous target. From previous studies conducted in the lab, it has been observed that an enhanced inter-individual variability in decision-making during reversal learning. Noteworthy, the decision-making of individual mice can be predicted based on their intrinsic state of anxiety and activity of stress response. Here, we aim at investigating: 1) How individuality affects decision making and 2) The neuronal activity controlling decision making and the selection of specific behavioral responses. We observed that based on their individual behaviour and intrinsic anxiety, the time taken to reach a goal platform as well as the distance covered by each mouse differs from one another.

Le travail de recherche réalisé au cours de cette thèse s'intéresse à la nature des représentations spatiales formées par le cortex entorhinal médian (CEM). Tout d'abord, nous montrons que le CEM code spécifiquement une information de distance, l'une des composantes nécessaires pour que l'animal puisse réaliser un type de navigation reposant sur les informations idiothétiques, appelé intégration des trajets. Puis, nous observons que le système vestibulaire, une source importante d'informations idiothétiques, influence l'activité thêta du CEM et permet la modulation de ce rythme thêta par la vitesse de déplacement des animaux. Ensuite, nous montrons que l'activité du CEM est nécessaire à la stabilité de l'activité des cellules de lieu. Parallèlement, nous observons que l'activité des cellules grilles du CEM est modifiée par les informations contenues dans l'environnement (allothétiques).Dans leur ensemble, nos résultats montrent que le CEM traite et intègre des informations idiothétiques mais aussi des informations allothétiques. Ces données suggèrent que la carte spatiale du CEM ne fournit pas une métrique universelle reposant sur les informations idiothétiques, mais possède un certain degré de flexibilité en réponse aux changements environnementaux. De plus, cette carte spatiale entorhinale n'est pas requise pour la formation de l'activité spatiale des cellules de lieu, contrairement à ce que suggère l'hypothèse dominante. / The work conducted during my PhD thesis was aimed at understanding the nature of the spatial representation formed by the the medial entorhinal cortex (MEC). First, we show that the MEC codes specifically distance information which is necessary for a type of navigation based on idiothetic cues, called path integration. Then, we observe that the vestibular system, an important source of idiothetic information in the brain, influences the MEC theta rhythm and its modulation by the animal velocity. In addition, we show that MEC activity is necessary for the stability of place cells activity. Finally, we observe that entorhinal grid cells activity is modified by the information available in the environment (allothetic information).Together, our results show that the MEC processes and integrates idiothetic information as well as allothetic information. These data suggest that the entorhinal map is not a universal metric based on idiothetic information, but is flexible and dependant on the information present in the environment. In addition, the entorhinal map is not required for the generation of place cells activity, contrary to the dominant hypothesis.