Researchers closer to understanding how smells link with memories

A study in mice finds connections between scents and learning and memory function.ByChia-Yi Hou | Sept. 25, 2021


Story at a glance

  • Our senses stimulate various parts of the brain.
  • New research in mice shows how smells activate different areas, especially parts of the brain for emotion and memory.
  • The researchers hope that future work can further help us understand the role of smell in memory formation.

Smells can be strongly associated with a person or place, and even a memory. How that exactly happens in the brain, however, is still a bit of a mystery. In a study published in the journal Cerebral Cortex, a team of researchers examines how scents take on meaning by looking at what parts of the brains of rodents are activated.

In experiments, they found that the scents are closely tied to the reward and aversions centers of the brain. “We already knew that there is a connection between the olfactory bulb and the piriform cortex, a part of the olfactory cortex, in the perception of scents,” explains Christina Strauch, who is lead author of the study, in a press release. “But our goal was to go deeper into the brain structures and find out which regions we had underestimated or overlooked until now.”

In the study, the team exposed mice to scents and electrophysiological stimulation while conducting functional magnetic resonance imaging (fMRI). In particular, they were interested in seeing which parts of the brain were activated and if it resulted in any changes in how genes were activated in the neurons. “So far, only a few studies on olfactory perception have analysed regions outside the olfactory bulb and olfactory cortex regions in rodents,” says Denise Manahan-Vaughan, who is the spokesperson of Collaborative Research Centre 874 Integration and Representation of Sensory Processes, in the press release. “It is still not completely understood how olfactory memories are formed. Our goal was to clarify to what extent brain structures that aren’t part of the olfactory system are involved in olfactory memory formation.”

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The results suggest that the stimulation of the olfactory bulb also led to changes in gene expression. They saw this in the limbic cortex, which is a part of the brain that is associated with the processing of emotions. “The involvement of these non-olfactory structures probably plays a key role in the storage of olfactory experiences,” says Strauch in the press release. “We deduce from this that rodents quickly categorise perceived scents as pleasant or unpleasant while smelling them.”

This study suggests that the olfactory system is involved with learning and memory formation because of how it interacts with the brain’s reward and aversion systems. Manahan-Vaughan says in the press release, “The study provides us an additional theoretical basis for understanding why the sense of smell plays such a unique role in the formation and retrieval of memories.”

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