Aside from enabling us to exchange gases with the universe and stave off suffocation, breathing also coordinates electrical activity in numerous regions of the brain, and therefore has a major effect on mental function, according to a study published earlier this month in the Journal of Neuroscience. Crucially, the study authors discovered that this synchronization of brainwaves is particularly strong when inhaling as opposed to exhaling and when breathing through the nose rather than the mouth.
The idea that breathing can impact neural activity has been around for a number of decades, and began when scientists started to speculate that breathing through the nose may create a direct link between the respiratory system and the brain’s olfactory bulb, which processes smells. Experiments on rodents in the mid-20th century then revealed that brainwaves are indeed synchronized with breathing patterns, but until now this had never been confirmed in human subjects.
The researchers therefore “borrowed” seven epilepsy patients who had had electrodes implanted in their brains in order to study their neural activity during seizures, and took a look at their brainwaves while monitoring their breathing.
This revealed that electrical oscillations across the brain occurred in time with each person’s breathing rhythm. This effect was particularly noticeable in the piriform cortex, which is connected to the olfactory bulb, the hippocampus, which processes memory, and the amygdala, which is involved in emotional regulation.
When participants were asked to breathe through their mouth rather than their nose, however, this synchronicity was greatly diminished.
To test the implications of this finding, the team then monitored the breathing rate of 21 volunteers as they took part in an emotional perception task, during which they had to observe a series of images of faces and identify the angry ones.
A further 75 people where simultaneously asked to complete a memory challenge, whereby they viewed two series of images 20 minutes apart and had to identify which pictures in the second set had also appeared in the first set.
Results showed that participants were better at identifying both the angry faces and the previously observed images when inhaling rather than exhaling and when breathing through the nose rather than the mouth. This is exactly what the researchers had expected to find, as it is under these conditions that brainwaves in the brain’s memory and emotion centers are most strongly coordinated.
The authors therefore conclude that breathing in through the nose could enhance cognitive functions like memory recall and emotional regulation, which may partly explain why our breathing rate tends to increase when we are under stress and need to think fast in order to resolve a crisis.