Speaker
Description
New memories are initially labile and have to be consolidated into stable long-term representations. Current theories assume that this is supported by a shift in the neural substrate that supports the memory, away from rapidly plastic hippocampal networks towards more stable representations in the neocortex. Rehearsal, i.e., repeated activation of the neural circuits that store a memory, is thought to crucially contribute to the formation of neocortical long-term memory representations. We investigate memory consolidation in the human brain by non-invasive in-vivo imaging of functional brain activity (fMRI, EEG) and microstructural plasticity (DW-MRI). Our studies demonstrate that active rehearsal of learning material during wakefulness can facilitate rapid systems consolidation, leading to an immediate formation of lasting memory engrams in the neocortex, even when participants study complex episodic narratives. These representations, observed in both brain activity and brain microstructure, satisfy general mnemonic criteria: They are long-term stable, drive behavior, and code the specific content of what has been learnt.