How Smells Turn into Long-Lasting Memories

Certain scents can trigger memories from years ago. Neuroscientists Dr. Christina Strauch and Prof. Denise Manahan-Vaughan from Ruhr-Universität Bochum investigated the area of ​​the brain responsible for storing scents as long-term memories.

Current research shows that the piriform cortex, part of the olfactory system, is involved in the process of rescuing these memories. However, this mechanism only works in interaction with other brain regions. "It's known that the piriform cortex can temporarily store olfactory memories. We wanted to find out if this also relates to long-term memories, " says Christina Strauch.

Artificial sensations through stimulation

Synaptic plasticity is responsible for storing memories in the brain's memory structures. During this process, communication between neurons changes through synaptic plasticity, which leads to memory formation. Strauch and Manahan-Vaughan examined whether the piriform cortex of rats was capable of expressing synaptic plasticity and whether this change lasted longer than four hours, indicating that long-term memories had been established. Researchers used electrical impulses in the brain to mimic the processes that trigger the encoding of olfactory sensations into memory. They employed various stimulation protocols that varied in pulse frequency and intensity. These protocols are known to induce long-term effects in another brain region responsible for long-term memories, the hippocampus. Strikingly, these same protocols did not induce long-term information storage in the form of synaptic plasticity in the piriform cortex.

A signal from a higher brain region is necessary.

Strauch and Manahan-Vaughan wondered whether the piriform cortex needed to be "instructed" to create long-term memories. To do this, they stimulated a higher brain region called the orbitofrontal cortex, which is responsible for discriminating between sensory experiences. This time, the stimulation induced the desired change in the piriform cortex. "Our research shows that the piriform cortex can indeed serve as an archive for long-term memories. However, it requires instructions from the orbitofrontal cortex that specific events are to be stored as long-term memories ," explains Strauch.