Navegando por Autor "Billwiller, Francesca"

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Electrophysiological evidence that the retrosplenial cortex displays a strong and specific activation phased with hippocampal theta during paradoxical (REM) sleep
(2017-07-20) Koike, Bruna Del Vechio; Farias, Kelly Soares; Billwiller, Francesca; Almeida-Filho, Daniel; Libourel, Paul-Antoine; Tiran-Cappello, Alix; Parmentier, Régis; Blanco, Wilfredo; Ribeiro, Sidarta Tollendal Gomes; Luppi, Pierre-Herve; Queiroz, Claudio Marcos Teixeira de
It is widely accepted that cortical neurons are similarly more activated during waking and paradoxical sleep (PS, aka REM) than during slow wave sleep (SWS). However, we recently reported using Fos labeling that only a few limbic cortical structures including the retrosplenial (RSC) and anterior cingulate (ACA) cortices contain a large number of neurons activated during PS hypersomnia. Our aim in the present study was to record local field potentials (LFPs) and unit activity from these two structures across all vigilance states in freely moving male rats to determine whether the RSC and the ACA are electrophysiologically specifically active during basal PS episodes. We found that theta power was significantly higher during PS than during active waking (aWK) similarly in the RSC and hippocampus (HPC) but not in ACA. Phase-amplitude coupling between HPC theta and gamma oscillations strongly and specifically increased in RSC during PS compared with aWK. It did not occur in ACA. Further, 68% and 43% of the units recorded in the RSC and ACA were significantly more active during PS than during aWK and SWS, respectively. In addition, neuronal discharge of RSC but not of ACA neurons increased just after the peak of hippocampal theta wave. Our results show for the first time that RSC neurons display enhanced spiking in synchrony with theta specifically during PS. We propose that activation of RSC neurons specifically during PS may play a role in the offline consolidation of spatial memories, and in the generation of vivid perceptual scenery during dreaming.
Hippocampus-retrosplenial cortex interaction is increased during phasic REM and contributes to memory consolidation
(Springer Science and Business Media LLC, 2021-06-22) Almeida Filho, Daniel Gomes de; Koike, Bruna Del Vechio; Billwiller, Francesca; Farias, Kelly Soares; Sales, Igor Rafael Praxedes de; Luppi, Pierre-Hervé; Ribeiro, Sidarta Tollendal Gomes; Queiroz, Claudio Marcos Teixeira de
Hippocampal (HPC) theta oscillation during post-training rapid eye movement (REM) sleep supports spatial learning. Theta also modulates neuronal and oscillatory activity in the retrosplenial cortex (RSC) during REM sleep. To investigate the relevance of theta-driven interaction between these two regions to memory consolidation, we computed the Granger causality within theta range on electrophysiological data recorded in freely behaving rats during REM sleep, both before and after contextual fear conditioning. We found a training-induced modulation of causality between HPC and RSC that was correlated with memory retrieval 24 h later. Retrieval was proportional to the change in the relative influence RSC exerted upon HPC theta oscillation. Importantly, causality peaked during theta acceleration, in synchrony with phasic REM sleep. Altogether, these results support a role for phasic REM sleep in hippocampo-cortical memory consolidation and suggest that causality modulation between RSC and HPC during REM sleep plays a functional role in that phenomenon

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Navegando por Autor "Billwiller, Francesca"