Encoding vs retrieval of episodic memory in rats: different theta oscillatory signatures in hippocampo-cortical networks according to individual episodic memory profile - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Communication Dans Un Congrès Année : 2021

Encoding vs retrieval of episodic memory in rats: different theta oscillatory signatures in hippocampo-cortical networks according to individual episodic memory profile

Résumé

Episodic memory, our capacity to recollect particular life episodes, has been initially defined in terms of the information it contains : what, where and in which context/when an event takes place. Pioneering studies on food-caching birds have demonstrated that animals are also able to form such complex memories. Using an original behavioral paradigm developed in our group, we confirmed that rats were indeed able to form episodic-like memory associations and retrieve them 24h later. Rats were exposed briefly to two successive episodes, during which unique odor-place-reward combinations (“what and where” information) were presented in different enriched multisensory contexts. We reported individual episodic memory profiles: some rats (“www” ) were indeed able to form and retrieve a complete memory of the episode while other animals (“Others”) remembered only parts of the information from the initial episodes. In the present study we first compare the ability of the rats to retrieve an episode either after 24h or 24 days. This behavioral study was performed on a group of 15 rats and combined to multi-site local field potentials recordings. The network of structures investigated included olfactory brain areas, lateral and medial prefrontal cortex and the dorsal and ventral part of the hippocampus. The objective was to investigate potential differences in the neural circuits involved in recent vs remote episodic retrieval. We focused our analysis on odor-induced changes in power in the theta band (3-12Hz) and compare “www” and “others” animals in the different experimental situations (encoding, recent vs remote memory). We found that the network of activated brain regions in theta frequency band differed as both a function of individual memory profiles as well as a function of memory age. As expected, the theta network is large especially during encoding. From the data obtained so far, two main results emerged: 1) during encoding we already observed differences in theta network activities according to individual memory profiles. 2) Prefrontal regions were already involved in episodic memory encoding from the very beginning and hippocampal regions stay engaged in the network supporting remote episodic recollection.

Domaines

Neurobiologie
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Dates et versions

hal-03432751 , version 1 (10-12-2021)

Identifiants

  • HAL Id : hal-03432751 , version 1

Citer

Nadine Ravel, Alexandra Gros, David Meunier, Samuel Garcia, Belkacem Messaoudi, et al.. Encoding vs retrieval of episodic memory in rats: different theta oscillatory signatures in hippocampo-cortical networks according to individual episodic memory profile. Neurofrance 2021, May 2021, Virtual meeting, France. ⟨hal-03432751⟩
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