Deep Breaths for Memory

Scientists at Northwestern Medicine have discovered that the rhythm of breathing creates electrical activity in the human brain that enhances memory recall and emotional judgments.

Christina Zelano, the lead author of this study and an assistant professor of neurology at the Feinberg School of Medicine at Northwestern University, stated that there is a dramatic difference in activity in the brain during inhalation as compared with exhalation. Breathing in stimulates neurons in the olfactory cortex, hippocampus, and amygdala and all across the limbic system.

The olfactory system, or sense of smell, detects substances that are airborne, while an accessory system senses stimuli that are fluid-phased.  

The hippocampus is part of the limbic system that directs many bodily functions. Located near the center of the brain in the brain's medial temporal lobe, it is involved in the storage of long-term memory including past knowledge, events, facts, and experiences. It is not involved with short-term memory and procedural memory such as motor actions like walking.   

The amygdala is a cell mass located within the brain’s temporal lobes. There are two amygdalae with one in each hemisphere of the brain. The amygdala is a structure of the limbic system that is involved in emotional processing and motivations, particularly those that have to do with survival and the processing of emotions like anger, pleasure, and especially fear. 

The scientists studied seven epilepsy patients who were scheduled for brain surgery. A week before surgery, electrodes were implanted into the patients' brains to identify the origin of their seizures. This allowed the scientists to get electro-physiological data directly from the brains of the patients. The electrical signals indicated that brain activity fluctuated with breathing and occurred in areas of the brain where memory, emotions, and smells are processed. That discovery led scientists to wonder whether cognitive functions associated with these brain areas, particularly fear processing and memory, could also be affected by breathing.

One’s behavior is affected depending on whether a person inhales or exhales and whether breathing is done through the nose or through the mouth. Scientists had approximately 60 subjects make decisions rapidly on presented emotional expressions while their breathing was recorded. Study individuals identified a fearful face quicker when breathing in rather than breathing out. They were more likely to remember an object if they encountered it on the inhaled breath than on the exhaled one. The effect was specific to fearful stimuli only during nasal breathing and disappeared if the breathing was done through the mouth.

The findings also imply that rapid breathing may be an advantage when in a dangerous situation. In a panic state, breathing rhythm becomes faster. Proportionally more time is spent inhaling than when a person is in a calm state. The body's response to fear with faster breathing seems to have a positive impact on brain function and results in a faster response time to dangerous stimuli in the environment.