Hippocampo-Cortical Coupling for Memory Consolidation During Sleep
Dates:1 September 2016 - 30 June 2017
Date limite de candidature:1 September 2016
Lab rotation proposal:
~ Sep-Dec 2016 ~ Jan-March 2017 ~ Apr-June 2017
Seminal work in the late 50s, later complemented by animal studies, have established that the hippocampus is a key brain structure involved in memory, in particular episodic and spatial memories. An influential theory postulates that information initially encoded in the hippocampus are progressively transferred to the neocortex for long term storage. This process is referred to as 'memory consolidation', and appears to occur during offline states such as slow wave sleep. Several brain rhythms could be involved, in particular slow oscillations and thalamo-cortical spindles, as well as hippocampal ripples, but their interactions remain poorly understood. Our team has recently confirmed that ripples play a critical role in memory consolidation, a long standing hypothesis that had inspired countless studies but had never been validated. Further, we now have data that confirms the complementary role of the cortex. We have dynamically manipulated the temporal coordination between the two structures during sleep following training on a spatial memory task specifically designed to trigger encoding but not memory consolidation. Reinforcing the endogenous coordination between hippocampal sharp wave-ripples, cortical delta waves and spindles by timed electrical stimulation resulted in high recall performance on the next day, contrary to control rats that performed at chance levels. The goal of the current project is to further examine hippocampo-cortical couplings, in terms of brain rhythms as well as neuronal ensemble activity, underlying the consolidation of memory traces. We will therefore monitor the ongoing activity of dozens of neurons recorded simultaneously across hippocampal and cortical regions in freely behaving rats, both during spatial navigation tasks and sleep. This will involve massive recordings in freely behaving rats, and complex analysis of multichannel signals recorded across brain areas.
Address: Collège de France - 11, Place Marcelin Berthelot 75231 Paris Cedex 05
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