A shot of espresso, a piece of chocolate or a headstand – all of these have been recommended before taking a big test. The best advice, however, could be to take a deep breath.

According to research conducted in the neurobiology lab of Prof. Noam Sobel of the Weizmann Institute of Science in Rehovot, people who inhaled when presented with a visuospatial task were better at completing it than those who exhaled in the same situation.

The results of the study, published in the March 2019 issue of Nature Human Behavior, suggest that the olfactory system may have shaped the evolution of brain function far beyond the basic function of smelling.

Ofer Perl, who led the research as a graduate student in Sobel’s lab, explains that smell is the most ancient sense: “Even plants and bacteria can ‘smell’ molecules in their environment and react. But all terrestrial mammals smell by taking air in through their nasal passages and passing signals through nerves into the brain.”

This ancient sense may have set the pattern for the development of other parts of the brain. The act of inhalation may prepare the brain for taking in new information – in essence, synchronizing the two processes.

Indeed, studies from the 1940s on found that the areas of the brain involved in processing smell – and thus inhalation – are connected to those that create new memories.

The new Israeli study started with the hypothesis that parts of the brain involved in higher cognitive functioning may also have evolved along the same basic template, even if these have no ties whatsoever to the sense of smell.

The sniffing brain

“In other mammals, the sense of smell, inhalation and information processing go together,” said Sobel. “Our hypothesis stated that it is not just the olfactory system, but the entire brain that gets ready for processing new information upon inhalation. We think of this as the ‘sniffing’ brain.”

To test their hypothesis, the researchers measured the air flow through the nostrils of subjects as they were presented with test problems to solve. These included math problems, spatial visualization problems (in which they had to decide if a drawing of a three-dimensional figure could exist in reality) and verbal tests (in which they had to decide whether the words presented on the screen were real).

The subjects were asked to click on a button when they had answered a question and again when they were ready for the next question. The researchers noted that as the subjects went through the problems, they took in air just before pressing the button for the next question.

The researchers ensured that the subjects were not aware that their inhalations were being monitored, and they also ruled out the possibility that the button-pushing itself was the reason for inhaling, rather than preparation for the task.

More inhaling = more successful problem-solving

Next, the researchers gave subjects only spatial problems to solve. Half were presented as the test-takers inhaled, and half as they exhaled. Inhalation turned out to be significantly tied to successful completion of the test problems.

During the experiment, the researchers measured the subjects’ electric brain activity with EEG, and here too they found differences between inhaling and exhaling, especially in connectivity between different parts of the brain.

This was true during rest periods as well as in problem-solving, with greater connectivity linked to inhaling. Moreover, the larger the gap between the two levels of connectivity, the more inhaling appeared to help the subjects solve problems.

“One might think that the brain associates inhaling with oxygenation and thus prepares itself to better focus on test questions, but the time frame does not fit,” said Sobel. “It happens within 200 milliseconds – long before oxygen gets from the lungs to the brain. Our results show that it is not only the olfactory system that is sensitive to inhalation and exhalation – it is the entire brain. We think that we could generalize and say that the brain works better with inhalation.”

Sobel points out that the word “inspiration” means both to breathe in and to move the intellect or emotions. Those who practice meditation know that breath is key to controlling emotions and thoughts. The study provides important empirical support for these intuitions, and it shows that our sense of smell most likely provided the prototype for the evolution of the rest of our brain.

The scientists think their findings could lead to research into methods to help people with attention and learning disorders improve their skills through controlled nasal breathing.