The mammillary bodies and memory: from encoding to consolidation

The mammillary bodies—tiny, almond-shaped clusters of neurons deep in the brain—are being put under a dual microscope in rats and humans to settle a long-standing debate about whether they simply help form new memories or also actively solidify them during sleep. For decades, these structures were thought to be involved only in memory encoding, the initial moment of learning. But recent rodent work from this team suggests they may play a second, unexplored role in memory consolidation—the process that stabilises and stores memories after they are formed. This matters because damage to the mammillary bodies is common in conditions like Korsakoff syndrome and some forms of dementia, yet current models of memory cannot explain why such damage causes severe amnesia. Without knowing what the mammillary bodies actually do, treatments remain blunt. This project is fundamental science. It will combine calcium imaging and electrophysiology in rats with fMRI in humans to track mammillary body activity during wakefulness and sleep, both in healthy brains and after targeted disruption. If successful, it will produce the first comprehensive model of how these structures contribute to post-encoding memory processing. That model could eventually inform diagnostic markers for amnesic disorders or guide rehabilitation strategies, but the immediate payoff is a clearer understanding of a core, unsolved piece of the memory puzzle.