Smells can reinvigorate old memories in a way that doctors could use to treat memory-related mood disorders, suggests a study in mice from Boston University.

Research in mice suggests that smell helps consolidate memories and may help people overcome trauma.
The nature of memory is one of the biggest mysteries of neuroscience. Memories are at the basis of who we are, and how the brain processes and consolidates them is the subject of work around the globe.

A recent study from Boston University’s Center for Systems Neuroscience has shown the power of smell in recalling memories, challenging a decades-old theory in the process.

The new research appears in the journal Learning and Memory.

The power of the hippocampus
The hippocampus — a small brain structure shaped like (and named after) a seahorse — is critical in the process of memory formation.

People with damage to the hippocampus are often unable to form new memories, and the region is also one of the most vulnerable in Alzheimer’s disease.

Experts think that when memories first form, the hippocampus processes them and captures rich, contextual details in the memory.

Over time, and particularly during sleep, the prefrontal cortex, or front of the brain, processes the memory, where many of the details embedded by the hippocampus become lost.

Scientists call this the systems consolidation theory, and it helps to explain why memories become ‘fuzzier’ over time.

Putting theory to test
According to this theory, recalling a memory shortly after it happens involves activation of the hippocampus, whereas remembering an old memory involves activation of the prefrontal cortex.

This is because the same brain cells that are active when a memory forms reactivate when a person recalls that memory.