The rhythm of breathing creates electrical activity in the human brain, which is responsible for enhancing emotional judgments and memory recall. The research suggested that the effects on behavior depend on whether the breathing process is done through the nose or the mouth, as well as whether the subjects breathe in or out.

It is the first time that such an association is made between the human cognitive positioning toward information and the breathing process.

The study, published Dec. 6 in the Journal of Neuroscience, was conducted by senior author Jay Gottfried, professor of neurology at Feinberg.

Fear Stimuli In Facial Expressions, Connected To Breathing

As part of the research, the subjects could identify a fearful face easier when they were breathing in, compared to exhaling. Additionally, the subjects were also more prone to remembering an object encountered when breathing in rather than breathing out.

"One of the major findings in this study is that there is a dramatic difference in brain activity in the amygdala and hippocampus during inhalation compared with exhalation," noted Christina Zelano, lead author of the study and assistant professor of neurology at Northwestern University Feinberg School of Medicine.

The researchers came across these discrepancies in brain activity while monitoring seven patients with epilepsy, and were supposed to go through a brain surgery. One week before the surgery, a brain surgeon inserted electrodes into the subjects' brains, to locate the origins of their seizures.

The procedure allowed researchers to understand the mechanisms of the electro-physiological data from the patients' brains, and understood that brain activity was fluctuating depending on the rhythm of breathing. The brain activity changing along with the breathing process was located to take place in the areas of the brain that are responsible with processing memory, emotions, and smells.

Recognizing Fearful Faces - Easier When Inhaling

The amygdala, which is directly connected to the way people process emotions, especially the ones related to fear, was involved in the recognition processes post-exposure to a series of stimuli.

Roughly 60 people were asked to decide, as fast as they could, whether the emotional expressions to which they were subjected in the laboratory expressed fear or surprise. The team has noticed that the subjects who were first presented the images during inhalation recognized the pictures as being fearful quicker than during breathing out.

However, the results did not replicate when it came to recognizing faces which expressed surprise. The effects of this process were lower when the subjects were asked to go through the same process while breathing through their mouths.

According to the results of the research, the association between breathing in and easily identifying a facial expression showing fear was only observed as the subjects were breathing through their nose.