As the smell of vanilla fills the air, you are taken back to your childhood days when your grandmother baked you chocolate chip cookies after school. Maybe she was wearing a bun that day, with a stray patch of flour decorating her hair, or maybe she was wearing her favorite velvet pants that she claimed were fashionable. Whatever it is, the smell of vanilla has kick-started your recall of a memory. But why do smells have such a hold over our past?
Emerging research has shown that this can be credited to the direct links between olfaction (your sense of smell), which uses the olfactory bulb, and the amygdala and hippocampus, which work together to store and recall emotional memories. Your other senses, like vision, don't pass directly through these structures, so it might be that this is why olfaction can evoke such strong sensations and bring back such strong memories and emotions.
For more info, check out this article from Psychology Today: https://www.psychologytoday.com/blog/brain-babble/201501/smells-ring-bells-how-smell-triggers-memories-and-emotions