What did you have for dinner last night? The ability to answer this question relies on episodic memory, our memory for past events and experiences. Episodic memories are the scaffold of human thought and action, allowing us to learn from the past and guide adaptive behaviour in the future. However, how these memories are created is still not well understood. Critically, research has shown that sleep after initial learning plays a crucial role in memory consolidation, which is the process of stabilizing new memories over time. However, the exact brain mechanisms during sleep that help consolidate memories are unclear. This gap in knowledge limits our overall understanding of memory formation and how we might bolster memories during sleep.
The SPIN project aims to test an exciting hypothesis: specific patterns of brain activity during sleep, known as sleep spindles, are essential for memory consolidation. The theory suggests that sleep spindles, working together with memory reactivation events in the hippocampus (a key memory area of the brain), are sent to cortical brain areas where they cause lasting changes that strengthen memories.
To explore this idea, we use advanced brain recording and stimulation techniques. First, we employ direct electroencephalography (iEEG) recordings from inside the brain in patient groups to measure activity in the hippocampus, the aforementioned memory hub, alongside various cortical areas during sleep. This will help determine if spindles indeed align with hippocampal memory reactivation events, pointing to a relay function between the hippocampus and cortical regions. Next, we use scalp EEG and magnetic resonance imaging (MRI) in healthy participants to see if the deployment of spindles to particular cortical sites predicts structural changes in those brain regions as a function of learning and memory. Finally, we examine the impact of enhancing and disrupting spindles on memory consolidation, paving the way for interventions to strengthen memories overnight and perhaps even diminish the persistence of unwanted memories.
In summary, SPIN uses a wide range of advanced brain recording and stimulation methods to uncover the link between learning, sleep, and brain changes. This research could lead to new tools for enhancing human learning and memory.
