Sniffing out a memory

Sometimes we smell something and suddenly it brings to mind a memory we’ve forgotten for many years. Maybe we smell a particular spice and remember a dish we loved as children. Smell is very strongly connected to memory. 


How do we smell?

When we smell something, chemicals travel into our nose where they bind to receptors. This sends a signal to an area of the brain called the olfactory bulb. The olfactory bulb is connected to areas of the brain such as the amygdala and the hippocampus. These areas are important for emotion and memory. 


What do the amygdalae do?

The amygdalae are two brain areas particularly involved in emotion. One is in the left side of the brain and the other in the right side. The amygdala in the right side of our brain processes negative emotion. For example, it is more active when we feel threatened. The left amygdala processes positive emotions, like when we are given a reward.


The amygdala is also important for memory. This is because we remember something more strongly if we feel more emotional at the time that the memory is made. 


What does the hippocampus do?

The hippocampus is the part of the brain involved in making long term memories and accessing them. When it is damaged, people can develop amnesia. Amnesia is when you are not able to access the memories of past experiences. 


How are smell and fear related?

If a smell is linked to these areas, it might cause specific memories to be recalled.  This is important when smells are associated with bad memories. Sometimes people who have experienced a very bad event can have flashbacks when they smell particular things linked to that event. Flashbacks are when people remember past events as if they are currently happening.


Are memory loss and smell loss linked?

Alzheimer’s disease (AD) is caused by chemicals in the brain damaging cells and the connections between them. The main symptom of AD is memory loss. However, one of the early symptoms is loss of sense of smell. This might be linked to memory loss. The entorhinal cortex is next to the hippocampus. It is involved in memory and smell so when it’s damaged in AD, smell and memory are affected. Smell and memory loss seem very linked. 


How is the link between memory and smell used?

Some people put freshly baked food on their counter when they are trying to sell their house. It brings happy memories and so people are more likely to buy the house. You can use smell to help you remember things. If you keep a particular scent (such as a herb or spice) near you when you revise and then smell it in an exam, it might help you remember information!


Smell has such a big role in our daily lives. It’s amazing how important our nose is!




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