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Thesis defense – Robin Piquet

23 October 2023 / 14:30

Venue : BBS auditorium

Defense in French

Robin Piquet
Team : Decision and adaptation
Thesis director : Shauna PARKES


Role of the hippocampus in the contextual control of goal-directed behaviour


Every day we make decisions based on internal goals and on the expectation that a given action will lead to goal achievement. Such ‘goal-directed’ behaviour is critical for adapting to our environment and is defined as an intention to act that is driven by knowledge of both the causal relation between an action and its associated outcome, and the value or current desirability of that outcome. Much research has been dedicated to understanding the neurocognitive bases of goal-directed behaviour. Yet, the influence of context on this behaviour is not well understood. This thesis combines principles from Experimental Psychology and Neuroscience to explore how environmental context can modulate goal-directed action and the role of the hippocampus in this modulation. Contexts, understood as the environmental cues that surround a learning experience, have a strong influence on behaviour. Indeed, most animals are highly efficient at recognising their surrounding environment. Our environments signal the information to which we should attend and can also indicate the most appropriate response or action. This thesis will consider two situations in which context can potentially influence goal-directed behaviour. The first is when the context itself acts as a predictive cue and enters into associative competition with instrumental actions. The second is when the context acts as a gatekeeper to signal the most appropriate action at a given moment. The first empirical chapter uses both lesion and chemogenetic approaches to study the role of the hippocampus in goal-directed behaviour. We show inhibition of ventral, but not dorsal, hippocampus renders rats unable to adapt to changes in the causal relationship between an action and its outcome. We then test the hypothesis that this deficit is due to an inability to discern the relative validity of the action compared with the context as a predictor of reward. Using latent inhibition and Pavlovian context conditioning, we confirm that sensitivity to a degradation of the causal relationship between an action and its associated outcome relies on intact context-outcome learning and show that this learning is also dependent on activation of ventral hippocampus. Finally, we show that inhibition of ventral hippocampus terminals in the medial prefrontal cortex also impairs both instrumental contingency degradation and context-outcome learning. These results implicate a hippocampo-cortical pathway in adapting to changes in action-outcome contingencies and indicate that the psychological basis of this deficit is an inability to learn the predictive value of the context. In the second experimental chapter, we consider a situation where the context dictates the specific action-outcome relations that are in effect. We first confirm that the context can enter into such hierarchical associations, i.e., context-(action-outcome) associations, and show that rats do indeed modify their choice between actions depending on the context in which they are placed. It is then revealed that the ventral hippocampus is required for the encoding and retrieval of context-(action-outcome) associations but dorsal hippocampus is required only for retrieval. Importantly, the hippocampus was only required for goal-directed behaviour when rats were forced to use the context to identify the current action-outcome relationships. Taken together, these results show that the hippocampus, mainly through its ventral part, supports the contextual modulation of goal-directed behaviour. This research highlights the role of context in acquired behaviour and emphasises the importance of considering the influence of environmental context when studying action selection and choice behaviour.

Key Words

Goal-directed behaviour ; context ; choice ; hippocampus ; rodents ; DREADD



Francis CHAOULOFF, DR, INSERM U 1215, Univ. Bordeaux ; Président
Valérie DOYERE, DR, CNRS UMR 9197, Univ. Paris-Saclay ; Rapportrice
Sébastien BOURET, DR, CNRS UMR 7225, ICM Paris ; Rapporteur
Stéphanie TROUCHE, CR, CNRS UMR 5203, IGF, Univ. Montpellier ; Examinatrice
Shauna PARKES, CR, CNRS UMR 5287, Univ. Bordeaux ; Directrice de thèse

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23 October 2023
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