Every breath leaves a mark on the brain

When the pop-rock group The Police released the song Every breath you take, in 1983, many people interpreted it as a romantic song. But a close reading of the lyrics reveals another reality. It describes obsessive surveillance and possibly a case of stalking. "Every breath you take, every move you make... I'll be watching you". What probably no one imagined is that, four decades later, neuroscience would end up giving an almost literal meaning to this title. Not because someone is observing us from the outside, but because our own brain seems to follow each of our breaths very closely. According to a recent study led by Bradley Voytek, a specialist in cognitive science at the University of California San Diego, which has been published in The Journal of Neuroscience, each inspiration and each expiration leaves a specific imprint on brain activity.

Breathing is such an automatic activity that we barely pay attention to it. Adults take between fifteen thousand and twenty thousand breaths a day, and none are exactly the same as another. Sometimes we inhale deeply, other times superficially. And we often take a brief pause before exhaling or inhaling again. Emotional state, stress, concentration, or relaxation constantly modify the breathing pattern.

For years it has been known that breathing influences complex cognitive functions, such as attention, memory, perception, or emotional regulation. It had also been observed that certain brain oscillations synchronize with the respiratory rhythm. However, most studies have analyzed breathing in a generic way, as if it followed a regular rhythm, when in reality each cycle is slightly different. To delve into this issue, Voytek and his collaborators have analyzed intracranial brain recordings of sixteen people with epilepsy who, for clinical reasons, had electrodes temporarily implanted in various regions of the brain. In parallel, they have recorded breathing using nasal airflow sensors and respiratory belts.

The main novelty of this study consists of having compared, breath by breath, the shape of each respiratory cycle with that of the corresponding neuronal oscillations. They did not limit themselves to measuring their frequency, but also aspects such as the duration of inspiration and expiration, the amplitude, and the asymmetry of each breath. In a way, they analyzed the specific “signature” of each breath and looked for its reflection in brain activity.

The results were surprising. The concrete form of each breath is reflected in the way neural networks oscillate in various brain regions involved in cognitive and emotional processes. When an inhalation or an exhalation is longer or more intense, brain rhythms show equivalent changes. This relationship occurs breath by breath. The areas involved include the insula, the thalamus, various regions of the frontal cortex, and limbic structures related to emotions and memory, such as the amygdala and the hippocampus. It is, therefore, not a localized effect, but a distributed phenomenon that connects breathing with neural networks of great functional relevance.

Connection with the nose

One of the most interesting aspects is that this relationship is much clearer when measuring the airflow inhaled or exhaled through the nose than when taking into account the movements of the thorax or abdomen. This observation reinforces an idea that has been gaining scientific support in recent years. The brain not only detects that we are breathing, but it seems to be especially sensitive to the air circulating through the nasal passages. Nasal receptors send information to brain structures related to memory, emotions, and attention.

This research helps to better understand why practices as diverse as meditation, yoga or tai chi, or some breathing exercises used in sports, can influence mental state. The study does not prove that any specific technique is especially effective, but it offers a plausible biological basis. Voluntarily modifying the way of breathing can alter communication patterns between neurons and, consequently, can influence mental state.

Naturally, one must be cautious. The study was conducted with people with epilepsy and only a portion of the records showed this precise relationship between breathing and neuronal activity. Therefore, the authors emphasize that further research will be needed to determine to what extent these results can be generalized to healthy individuals or those with other conditions.

Despite these limitations, however, the underlying message is important. For a long time we have imagined the brain as a relatively independent organ, responsible for directing the rest of the body. However, there is increasing evidence that the relationship is bidirectional. The heartbeat, the state of the internal organs, hormones, and also breathing are part of a continuous conversation between the body and the brain. Each breath does not only sustain life. It also contributes to shaping, instant by instant, the activity of our mind.