The limbic system and smell memory
The hippocampus, the amygdala, and the Proust effect
Why odours are remembered differently
Anyone who has lost their sense of smell notices something odd: what disappears is not only the ability to tell odours apart, but something else that is hard to name. Food does not become unpleasant — it becomes nothing. Home stops smelling of home. This is not an exaggeration; it has an anatomical cause.
Vision, hearing and touch send their signal to the thalamus first, and only from there does it spread further. Smell is the only sense that bypasses the thalamus. From the olfactory bulb the signal goes straight to the piriform cortex, and next to it sit the amygdala and the hippocampus — the structures of emotion and memory.
Put simply, odour has a short path to feeling that the other senses do not.
The Proust effect
The literary example is well known: in Marcel Proust, the taste of a madeleine dipped in tea returns a whole layer of childhood to the narrator. The phenomenon was named after him, and it is real enough.
Memories triggered by smell differ from those triggered by a word or a picture. They more often reach back to early childhood, they come less frequently, and they are experienced more vividly and with more emotion. You do not so much recall them as fall into them.
The reason is that short path. An odour reaches the emotional centres before deliberate processing kicks in — the processing we normally use when we look for a memory on purpose.
What this means when smell is lost
First, the weight of the experience is justified. Smell loss regularly comes with low mood, and that is not weakness of character: a channel that carried an emotional connection to places, people and food has been cut. If the state persists, that is a reason to seek help rather than endure it.
Second, that same connection becomes a working tool. Since smell and memory sit next to each other, memory can be used as a lever. Not "sniff and move on", but sniff and pull up a specific scene: where you were, what was happening, who was there.
How to use it
What works is detail, not abstraction. "A citrus smell" is a poor anchor. "Lemon tea when I was ill as a child, and someone brought the cup" is a good one.
The app offers an anchor of that kind for every odour, but it is only an example. Your own memories are stronger than someone else's, and if cinnamon is tied for you not to baking but to a particular house in a particular year, use that.
And one more thing: you can write your own memory down. A personal anchor can be added to every odour, and your own scents can be created with your own photo and your own scene. The closer the stimulus is to your life, the more the brain has to hold on to.
