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Yogic breathing, which focuses on conscious nasal breathing, can stimulate the emotional centres of the brain. [Photo: Bigstock]

How breath stimulates emotion and awareness

If you have ever practiced conscious breathing, or yogic breathing, you will have experienced how it can alter your emotional state. The question bugging modern science is: just how does it do that?

Recently scientists at Northwestern University Feinberg School of Medicine in Chicago began to look into this question and discovered for the first time that how we breathe and the rhythm of our breathing creates electrical activity in the human brain that can enhance emotional judgments and memory.

These effects on behaviour, however, depend on whether you inhale or exhale and whether you breathe through the nose or mouth.

Study participants were, for example, able to identify a fearful face more quickly if they encountered that face when breathing in, compared to breathing out. ~They were also more likely to remember an object if they encountered it on the inhaled breath than the exhaled one. The effect disappeared if breathing was through the mouth.

Tapping into the emotional centre of the brain

“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. “When you breathe in, we discovered you are stimulating neurons in the olfactory cortex, amygdala and hippocampus, all across the limbic system.”

The amygdala and the hippocampus are part of the limbic system – the part of the brain where most of our emotions are processed. The amygdala is the emotional centre of the brain while the hippocampus plays important role in in both short- and long-term memory, and in spatial memory that enables navigation.

Northwestern scientists first discovered these differences in brain activity while studying seven patients with epilepsy who were scheduled for brain surgery.

A week prior to surgery, a surgeon implanted electrodes into the patients’ brains in order to identify the origin of their seizures. This allowed scientists to acquire electro-physiological data directly from their brains. The recorded electrical signals showed brain activity fluctuated with breathing. The activity occurs in brain areas where emotions, memory and smells are processed.

This discovery led scientists to ask whether cognitive functions typically associated with these brain areas – in particular fear processing and memory – could also be affected by breathing.

Fear and memory

The amygdala is strongly linked to emotional processing, in particular fear-related emotions. So scientists asked about 60 subjects to make rapid decisions on emotional expressions in the lab environment while recording their breathing. Presented with pictures of faces showing expressions of either fear or surprise, the subjects had to indicate, as quickly as they could, which emotion each face was expressing.

When faces were encountered during inhalation, subjects recognised them as fearful more quickly than when faces were encountered during exhalation. This was not true for faces expressing surprise. These effects diminished when subjects performed the same task while breathing through their mouths. Thus the effect was specific to fearful stimuli during nasal breathing only.

In an experiment aimed at assessing memory function – tied to the hippocampus – the same subjects were shown pictures of objects on a computer screen and told to remember them. Later, they were asked to recall those objects. Researchers found that recall was better if the images were encountered during inhalation.

The findings of the current study imply that, for example, 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.”

But another potential insight of the research is on the basic mechanisms of meditation or focused breathing. “When you inhale, you are in a sense synchronising brain oscillations across the limbic network,” Zelano noted.

• For more on this topic see out features Stop. Breathe. and Q&A: What is alternate nostril breathing?