How can we vividly remember so many episodes of our life that, by definition, only happened once? During wakefulness, the hippocampus – a brain structure critical for episodic memory – encodes ‘memory traces’ of our experience. During sleep, it “replays” the very same sequences of neurons that were originally activated during the awake episode. Such reactivations are essential for memory consolidation. Over the years, a growing body of studies have unveiled “on-site” reactivations within the hippocampus, sometimes with a neocortical or subcortical “partner” structure, but the overall activity in the brain during these events remains largely unknown.
This is a major knowledge gap because numerous cortical and subcortical structures strongly influence memory. Observing the key structures and the neural correlates of memory consolidation during sleep can have a significant impact on pathologies where such memory traces are over consolidated in conditions like posttraumatic stress disorders syndrome as for numerous neurogenerative disorders such as Alzheimer’s or Parkinson’s diseases are associated with disrupted memory processes and altered sleep architecture. The scope of this project is thus very broad and its impact far-reaching.
In this project, we aim to use a unique combination of groundbreaking recording and analysis techniques to reveal the whole-brain correlates of hippocampal replay and their dynamics throughout the life of a single memory from its creation to its long-term storage. In particular, the technique of functional ultrasound will enable us to track brain activity with unprecedented resolution during a well-defined behavioral task.
