Breathing in bestows a momentary boost to some brain functions
When you inhale, you’re obviously aiding brain function by drawing in oxygen to enable metabolic functions throughout your body, including perception and cognition. Multiple studies suggest that there’s another layer to the relationship between respiration and brain function though. Our brains have been found react to inhalation before any oxygen can make the trip through our lungs to our head, as brain function can sync up with each breath. At least as it goes through our nose.
Earlier research in animals established some of these neurological links to breathing. Brain waves in hedgehogs, for instance, were observed to be coupled to each breath the animals took. Some of these studies found more intuitive relationships, such as activity in the olfactory bulbs of mice linking up with inhalations, but recent work with humans has found that there’s more at work than just breathing in stimulating smells. While the piriform cortex (which does help process smells) was found to respond to changes in breathing, so did the hippocampus and the amygdala, which manage memory and emotion, respectively.
Syncing up more than smells
The specific tests actually avoided olfactory stimulation, and instead focused on visuals. Participants wearing breathing monitors were first tested on how well they could identify the emotions associated with facial expressions in photos. There was an improvement in responses when the participants were naturally inhaling air at the time they observed the images, particularly if those images showed a fearful expression. A second test showed people a range of images, then asked them to identify them again 20 minutes later. Images that were seen when a participant happened to be inhaling were more consistently remembered than those that were seen when exhaling. And in both tests, breathing through the nose was somehow key to these gains. Participants asked to breathe through their mouths didn’t benefit during inhalation in the same way.
Internally, these changes in test performance was likely due to the way the brain adjusted activity levels to align with breathing. The best results, such as correct answers on the memory test, came when brain waves in all three brain centers synced up with inhaling air. Exhaling generally saw a degradation of this synchronization, and as the test results suggested, breathing through the mouth led to even less alignment. We normally can’t choose to maximize these effects thanks to the unconscious nature of breathing, but it may be manipulated at times of excitement. In a panicked state, we often breathe faster, which increases the proportional time spent inhaling. Presumably, this gives our brain regions more time to work in sync, helping us think as clearly as possible when under pressure.
Source: Breathing modulates brain activity and mental function by Mo Costandi, The Guardian