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Le rappel en mémoire épisodique : la contribution du précuneus dans la reconstruction de l'expérience subjective et spatio-temporelle écologique des événements du passé

Abstract : In humans, episodic memory is the cognitive ability that allows them to recover a past experience, or episode, according to a specific state of consciousness. The particularity of this memory system is the construction of links between the contextual dimensions constituting the memory episode: the "What?" event, the "When?" moment, and the "Where?" place. Conventional studies of episodic memory indicate that these dimensions are processed and integrated into cortical structures mainly comprising the median temporal lobe and the prefrontal cortex. Recent studies of fMRI memory using more natural and ecological experimental materials have opened the perspective of underlying cortical networks of episodic memory extending beyond theses regions. Indeed, these studies suggest that the parietal lobe plays an important role in the constitution of a memory episode with an enriched context. However, the mechanisms and structures relating to the processing of the contextual features of an event remain debated, and the interactions induced between the different contextual dimensions of a memory episode, when it is recalled, are poorly understood. This thesis presents 3 main objectives: 1) to develop new experimental protocols to study the memory of encoded episodes in situations involving naturalistic and rich contexts; 2) to assess the influence of the temporal and spatial context on the recall performance of encoded episodes in these highly naturalistic situations; and 3) to elucidate the cortical structures underlying the treatment of these contextual dimensions. With these objectives in mind, I developed new protocols using films, virtual reality and a geolocated mobile application during the encoding phase. I studied the behavioral performance of recall, and related functional brain activity using fMRI, by means of 2 tasks: a hybrid Recall/Family and Source Memory task; and a temporal order judgment task. My behavioral results from the first task show that the correct and confident recall of the "Where?" place and the "When?" time predicts the probability of successful recall of the “What”? over and above any familiarity rating; and this, in all encoding modalities. The fMRI results showed increased activity in the Precuneus. In the task of judging the temporal order I observed a modulation of the retrieval reaction times, and activity of the Precuneus, as a function of the temporal distance between the episodes during the encoding phase. More importantly, through the studies, I have found that these behavioural and imaging effects are modulated according to other contextual factors associated with ecological episodes (e. g. spatial factors, semantic content, encoding modality), demonstrating that the episodic information processed by the Precuneus exceeds the traditional "what, where, when" dimensions. These results highlight the involvement of the medial parietal lobe in the recall of ecological memory episodes and suggest its involvement in the conscious and subjective memory recall. I interpret these results in the light of reconstructive theories of episodic memory and propose that the Precuneus is involved in the multidimensional integration of enriched memory episodes from an enhanced subjective/personal perspective. More generally, my studies support the importance of studying human cognition in naturalistic environments, by demonstrating here the crucial role of the Precuneus, which is a structure remote from the classic temporo-frontal network of episodic memory
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Submitted on : Tuesday, May 11, 2021 - 2:57:08 PM
Last modification on : Wednesday, May 12, 2021 - 3:35:12 AM


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  • HAL Id : tel-03224234, version 1


Samy-Adrien Foudil. Le rappel en mémoire épisodique : la contribution du précuneus dans la reconstruction de l'expérience subjective et spatio-temporelle écologique des événements du passé. Neurosciences [q-bio.NC]. Université de Lyon, 2020. Français. ⟨NNT : 2020LYSE1056⟩. ⟨tel-03224234⟩



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