Breathing has never been before linked to anything other than the intake of oxygen, but now it seems to have connections to brain function-- specifically, memory and fear. Northwestern Medicine scientists have found for the first time, that breathing rhythm induces electrical activity that enhances both memory recall and emotional judgements.
Interestingly, the behaviors depend on if one breathes through the mouth, or through the nose. For a bit of background knowledge regarding breathing, breathing is controlled by the body's autonomic nervous system, and the rate of breathing is controlled in the brainstem or the medulla.
There are various factors that affect breathing-- if oxygen levels get too high, specialized nerve cells within the aorta and the carotid arteries called "peripheral chemoreceptors" monitor the level and apply negative feedback on the respiratory centers in order to maintain homeostasis. The same negative feedback mindset applies for too much or too little carbon dioxide, however the method of control is completely different. A central chemoreceptor in the medulla monitors the carbon dioxide concentration within the cerebrospinal fluid (CSF) that cushions the brain and the spinal cord. If the carbon dioxide levels are too high, then the chemoreceptors will signal the respiratory centers to inhale more and increase breathing rates. pH is also key to breathing rates-- if the pH of the blood and CSF decreases, hence becoming more acidic, the chemoreceptors induce the respiratory centers to speed up, and vice versa. Chemical irritants often signal the respiratory centers to contract respiratory muscles, causing a sneeze or cough.
It's also been generally known that in intense emotions, such as pain or anger, the hypothalamus induces the respiratory centers to speed up. However, Northwestern researchers have found that in their study, participants were able to identify a fearful face or an object much more quickly if they encountered the face while breathing in, in comparison to breathing out. The effect did not work if breathing through the mouth.
“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,” said lead author Christina Zelano, assistant professor of neurology at Northwestern University Feinberg School of Medicine. “When you breathe in, we discovered you are stimulating neurons in the olfactory cortex, amygdala and hippocampus, all across the limbic system.”
Northwestern scientists found these differences between inhalation and exhalation from studying patients with epilepsy, implanting electrodes on their brain prior to surgery to find the source for the seizures. The electrical signals showed brain activity fluctuations associated with the breathing rates.
The amygdala is the part of the brain associated with emotions, particular fear-related ones. So, the scientists had asked 60 subjects to make quick decisions based off recognition when presented with emotional and surprised faces. Subjects recognized and recalled the fearful expression much faster with inhalation rather than exhalation, and breathing through the mouth had little to no effect. Therefore, the effect was specific to nasal breathing only, not oral. When assessing memory function, important to the hippocampus, the subjects who had inhaled were able to recall the faces much more faster than those who had exhalated.
“If you are in a panic state, your breathing rhythm becomes faster,” Zelano states. “As a result you’ll spend proportionally more time inhaling than when in a calm state. Thus, our body’s innate response to fear with faster breathing could have a positive impact on brain function and result in faster response times to dangerous stimuli in the environment.”
This finding is very important in recalling important or key details in dangerous scenarios and situations, and can be useful information for stabilizing electrical signal fluctuations for those who suffer from seizures. Rapid breathing may be much more useful than we think. Hopefully, the research can be used for more purposes, especially dangerous situations regarding fear and emotions.