Our breathing patterns, and their resulting impacts on the brain, can strengthen or weaken our memory-forming powers, new research reveals – and the findings could potentially help in the treatment of brain disorders and mental health problems.
The body's natural and spontaneous breathing behavior is known as medullary respiratory activity, after the medulla oblongata – the breathing control center of the brain. Of particular importance are a small cluster of neurons in what is known as the Pre-Bötzinger Complex (PreBötC), which sit inside the medulla oblongata.
"Breathing is a fundamental action in life support in mammals," says neuroscientist Nozomu Nakamura, from Hyogo Medical University in Japan. "Although details of respiratory function on brain states remain unclear, recent studies suggest that respiration may play an important role during online brain states."
In this new study, scientists interfered with the PreBötC in genetically modified mice. They found that when they temporarily stopped the mice from breathing, the animals were less able to form important memories during object recognition and fear conditioning tests.
What's more, pauses in breathing also seemed to affect the activity of the brain's hippocampus (key to long-term and short-term memory storage) during memory recall. In further tests, forcing irregular breathing patterns improved the memories of the mice, while slowing the breathing down worsened the mice memories.
Previous research from the same team had already demonstrated that switching from breathing out to breathing in at the start or in the middle of a memory task – technically known as the expiratory-to-inspiratory (EI) transition or inspiratory onset – made people slower and less accurate when recalling the information.
That was followed by a study that used brain scans to link the poorer memory performance with the deactivation of the temporoparietal junction or TPJ. The TPJ handles many different tasks, processing information from inside and outside the body and figuring out appropriate responses.
The researchers suggest that certain breathing patterns – including EI transition – reset the processing that the TPJ does, and that the TPJ might be involved in the memory performance fluctuations seen in the mice. These effects still need to be replicated in humans, which is one route to pursue in terms of future studies.
We're already aware of various links between breathing and the brain – the way that breathing exercises can help calm us down, for example – and the team behind the new paper suggests that deliberately adjusting our breathing patterns could help in other therapeutic ways.
"The determination of detailed roles of respiration and molecular mechanisms in the brain is a subject to future research to understand effects of stress tolerance," says Nakamura.
"The way of breathing manipulation and application of breathing exercises will be crucial for treatment and therapy of depression and neuropsychiatric disorders."
The research has been published in Nature Communications.