Folklore, spiritual traditions and even mothers have for ages drawn an implicit connection between respiration and state of mind: Breathe in deeply through your nose, we are told, to clarify thoughts, achieve serenity, defuse tantrums. There isn’t a lot of scientific evidence to back up these ideas, but a growing number of experiments have been looking at the influence that breathing has on our cognition. In October, a study in The Journal of Neuroscience considered the relationship between memory and how we breathe.

Recognizing odors is a key survival mechanism for most creatures — including humans, of course. This is why neuroscientists believe the links between thinking and breathing were early evolutionary adaptations. Studies have shown that when rodents sniff, the flow of even odorless air initiates brain activity by stimulating neurons in what’s called the olfactory bulb, which then signal the hippocampus, a part of the brain involved in the creation and storage of memories. For the October study, researchers at the Karolinska Institute in Stockholm, Sweden, and other institutions conducted an experiment to see whether something similar happens to us if we breathe through our mouths.