Have you ever breathed in deeply and been transported back in time to a moment from your childhood? Whether it's the tangy scent of salt-laced air at the beach or the spicy aroma of homemade pumpkin pie, certain smells can have a powerful effect on you, bringing up detailed memories that may be about as close to a time machine as you're likely to get.
Scientists that study the brain have learned a lot about why your nose seems to have a direct line to your memories. Here's how it works.
Basic Anatomy: How the Nose Is Connected to the Brain
First, it's helpful to understand exactly how your sense of smell works. When you breathe, the air passes along the olfactory neurons — your smell receptors — that are located deep inside your nose. There are at least 1,000 types of receptors up there, all designed to note the presence of different chemical compounds around you.
When triggered by the presence of a certain substance, the affected neurons fire and send a signal along the olfactory nerve, which travels from your nose to the olfactory bulb in the brain. This is where the brain decodes the message and arrives at a conclusion about what you smell, whether it's dogwood blossoms or dog poop.
In your brain, the olfactory bulb happens to be located right next to the hippocampus— the part of the brain that makes memories of your experiences. Scientists think that this proximity makes it much easier for scent to affect your memories than other senses since they're activated at the same time.
Why Smell Is a Uniquely Powerful Sense
Of your five senses, the ability to smell is the oldest one, from an evolutionary standpoint. It dates way back to how even the most basic living organisms can detect chemicals in their environment.
Other senses, such as sight and hearing, evolved much later. They also use a different pathway to the brain, taking information from your eyes or ears to the thalamus in the brain. The thalamus then decides where to send the signals next— it's like a sorting machine at the post office. Smell, however, has a direct line to the brain and bypasses the thalamus, heading instead to that spot near the memory-making part of your brain.
This is likely why smells can trigger such strong memories, along with the raw emotions that went with the experience. Senses that pass through the thalamus are easier to describe, but smell is much harder to talk about. For example, you can describe what chocolate looks like by talking about its color, shape, and texture, but you can only describe its smell by saying it smells like chocolate. This is probably why scents can trigger powerful emotional memories: There are no words to get in the way, only the "pure" memory and the feelings associated with it.
Your Personal Time Machine
Different scents affect people in different ways, though. If you have fond memories of the beach, you're likely to love the smell of the ocean. If you hated weeding the garden as a child, roses might not do it for you. Because your sense of smell is so personal, you should always follow your nose when it comes to adding aromas to your home. Choose scents that remind you of times you felt safe and happy, and you'll be able to connect to some of your fondest memories any time you like.