Olfaction sends signals to the brain influencing cognitive and emotional states.

“One is olfaction. So, when you're breathing, normal breathing, you're inhaling and exhaling. This is creating signals coming from the nasal mucosa that is going back into the olfactory bulb. That's respiratory modulating. And the olfactory bulb has a profound influence and projections through many parts of the brain. So, there's a signal arising from this rhythmic moving of air in and out of the nose that's going into the brain that has contained in it a respiratory modulation.”