New Research Suggests Breathing Plays a Crucial Role in Coordinating Brain Activity
A new study published in Scientific Reports has revealed that breathing may have a significant influence on brain activity, specifically in the prefrontal cortex. The findings shed light on the relationship between respiration and cognitive processing, providing valuable insights that could impact meditative practices involving controlled breathing.
Previous studies have already hinted at the impact of respiration on brain activity and cognitive processes. Changes in breathing patterns have been associated with alterations in attention, arousal, and emotional states. Additionally, the respiratory system shares neural pathways and connections with brain regions involved in cognition.
The researchers conducted their study focusing on the nucleus reuniens (Reu), a structure that acts as a bridge connecting the prefrontal cortex and the hippocampus. Their aim was to investigate how neural activity synchronization, particularly in the gamma rhythm frequency range, occurs within this network.
Gamma rhythm refers to a specific pattern of electrical activity characterized by high-frequency oscillations in the gamma frequency range, typically around 30 to 80 cycles per second (Hz). It is a major feature of brain activity and is associated with various cognitive processes such as attention, perception, memory, and consciousness.
Lead author Sunny Basha, a PhD candidate at Laval University and a member of the Timofeev Lab, explained, “We were intrigued by the idea that breathing can cause brain networks to continuously switch between synchronized states and desynchronized states. The synchronization of neural activity is a fundamental brain mechanism that is very closely linked to cognition, particularly when it emerges at the gamma frequency in prefrontal regions.”
Basha further noted, “Breathing is one of those behaviors that stimulates a surprisingly large set of senses, ranging from mechanical and thermal sensations evoked by air flowing through the nose, olfaction, the feeling of chest expansions, chemosensation from fluctuating CO2 and O2 levels and even hearing, which can be stimulated by the sound of air flow.”
The researchers utilized animal models, specifically cats and mice, for their study. They implanted electrodes in different brain regions, including the prefrontal cortex, hippocampus, midline thalamus, and various cortical areas. By recording local field potentials (LFP) and performing intracellular recordings of neural activity, they were able to measure the electrical activity of individual neurons. The researchers also monitored the animals’ respiration by recording temperature changes near the nostrils or using a piezoelectric sensor strip placed on the animal’s thorax.
The study revealed that the gamma rhythm plays a crucial role in understanding the relationship between respiration and brain activity. Specific brain regions, such as the prefrontal cortex and the midline thalamus, displayed synchronization between gamma oscillations and the respiratory cycle. This means that the respiratory cycle influenced the gamma oscillations in these regions, with different phases of the oscillations aligning with different phases of breathing.
Basha emphasized, “The main takeaway of our study is that breathing is a major pacemaker in cognitive areas of the waking brain. During exhalation, prefrontal regions go into a gamma oscillation and synchronize with the nucleus reuniens of the thalamus, an area which acts as a crucial link between the prefrontal cortex and the hippocampus.”
The study also highlighted that the synchronization between breathing and brain activity was primarily observed during wakefulness, suggesting that it is specifically related to the conscious state of being awake.
“As animals began to sleep, we observed that gamma oscillations decoupled from breathing cycles and became linked instead to internal sleep oscillations such as spindles,” Basha explained. “It suggests that there is a yet-undiscovered process that controls the coupling of gamma oscillations to breathing in the waking state.”
Furthermore, the researchers explored the origin of the breathing-related signals in the brain. They proposed that the entorhinal cortex, which receives input from the olfactory system, might be involved in generating these signals.
Basha concluded, “The brain is constantly monitoring the sensations that we evoke by our own behavior. With every breath you take, every move you make, every bond you break, the brain is watching you.”
The study titled “Respiration organizes gamma synchrony in the prefronto-thalamic network” was authored by Diellor Basha, Sylvain Chauvette, Maxim Sheroziya, and Igor Timofeev.