How Breathing Influences Brain Activity
JARA-BRAIN scientists have discovered that respiration and brain function correspond more closely with each other than previously believed. The results of their research have been published in the internationally respected journal Nature Communications.
Dr. Junji Ito works as a neuroscientist in the research group Statistical Neuroscience headed by JARA-BRAIN scientist Prof. Sonja Grün at the Institute of Neuroscience and Medicine at Forschungszentrum Jülich. In collaboration with American colleagues from the University of Tennessee, he discovered that there is a strong interaction between the breathing rhythm of mice and the activity of the whisker barrel cortex. This is an area of the brain in mice that processes the signals transmitted from their whiskers. “It was already known that the activity of the olfactory bulb – the area of the brain responsible for the sense of smell – is correlated to respiration. However, since we were unaware of any relationship between the whisker barrel cortex and breathing, these results come as a surprise,” says Ito. In the future, these results could also contribute to a better understanding of the role of breathing in human brain activity.
When analysing the data provided by researchers from the University of Tennessee, Ito discovered that the breathing rhythm is linked to the delta frequency of the local field potential. The field potential corresponds to the sum of synapse activity in one cubic millimetre of the brain. Delta waves are low-frequency brain waves (0.5– 4 Hz) that occur in both humans and mice, usually when they sleep. In the whisker barrel cortex of mice, however, they can also occur in a waking state.
"The results are clear: the mice breathe in out four times per second and there are four cycles of delta waves per second," explains the Jülich scientist. The link is not restricted to delta waves, however. Ito and his colleagues were able to show that in the whisker barrel cortex, gamma waves (> 30 Hz) also occur. They can usually be measured when concentration is very high or during learning processes. These gamma waves, the scientists found, are coupled to the delta waves and to respiration.
In further experiments, the researchers demonstrated that nasal airflow controls the interactions between respiration and neural activity in the barrel cortex. Whether this is also the case for other brain areas and whether it can be observed in humans will be the subject of future research projects. Sonja Grün assumes that interrelations will also be found in humans: “The role played by breathing in meditation is well known. We hope to find out more about how respiration impacts our ability to think.”