Breathing Rhythm Impacts Memory, Fear

The rhythm of your breathing impacts electrical activity in the brain that enhances emotional judgments and memory recall, according to a new study by scientists at Northwestern University.

These effects are strongly dependent on whether you inhale or exhale and whether you breathe through the nose or mouth.

In the study, participants were able to identify a fearful face more quickly if they saw the face while they were breathing in compared to breathing out. They were also more likely to remember an object if they encountered it while inhaling compared to exhaling. The effect disappeared if breathing was 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 Dr. 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 first discovered these breathing-brain activity patterns while they were studying seven patients with epilepsy who were scheduled to have brain surgery.

A week before the surgery, a surgeon implanted electrodes into the patients’ brains in order to determine the origin of their seizures. This allowed scientists to obtain electro-physiological data directly from their brains. The recorded electrical signals revealed that brain activity in areas associated with emotions, memory, and processing smells appeared to fluctuate with breathing.

This finding led the researchers to question whether other cognitive functions typically associated with these brain areas — in particular, fear processing and memory — could also be influenced by breathing.

Since the amygdala is strongly linked to emotional processing, particularly fear-related emotions, scientists decided to test whether breathing had an effect on recognizing others’ emotions.

They asked about 60 subjects to make rapid decisions on emotional expressions in the lab environment while recording their breathing. Presented with pictures of faces expressing emotions of either fear or surprise, the participants had to indicate, as quickly as they could, which emotion each face was showing.

When participants saw the faces while breathing in, they recognized them as fearful more quickly than when faces were encountered during exhalation. This was not true for faces expressing surprise.

These effects diminished when individuals performed the same task while breathing through their mouths. Therefore the effect was specific to fearful stimuli during nasal breathing only.

In another experiment aimed at assessing memory — a function tied to the hippocampus — the same participants were asked to recall pictures of objects they had previously seen on a computer screen. Researchers found that their recall was stronger if they had initially encountered the images while inhaling. The findings imply that rapid breathing may confer an advantage when someone is in a dangerous situation, Zelano said.

“If you are in a panic state, your breathing rhythm becomes faster,” Zelano said. “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.”

These findings may also reveal some of the underlying mechanisms behind meditation or focused breathing. “When you inhale, you are in a sense synchronizing brain oscillations across the limbic network,” Zelano noted.

The findings are published in the Journal of Neuroscience.

Source: Northwestern University