HMH scientists calculate breathing-brain wave rhythms in deepest sleep

(Press-News.org) Could the deepest parts of the brain hold some of the secrets of sleep that still remain elusive to science?

A team from Hackensack Meridian Health and its Center for Discovery and Innovation (CDI) have produced a new in-depth study penetrating into the brain, finding that during the deepest sleep, breathing patterns and brain activity become more independent from one another - unlike lighter sleep or quiet wakefulness.

The study was published in The Journal of Neuroscience in January, with the team led by CDI author Bon-Mi Gu, Ph.D., also of the Hackensack Meridian School of Medicine. The research team includes Kolsoum Dehdar, Ph.D., and Elliot Neuberg, and recently relocated from the Neuroscience Institute at Hackensack Meridian JFK University Medical Center to the CDI.

The paper focuses on the basal ganglia, clusters of neurons responsible for motor control and other roles. Of prime interest to the scientists is the tiny region called the substantia nigra, which controls movements and produces dopamine, among other functions. The relation between these structures and sleep - and how they relate to each other’s rhythm has not heretofore been widely studied, according to the scientists.

“In this study, we provide the first detailed characterization of respiration-neural coupling across multiple states - including quiet wakefulness, non-REM sleep, REM sleep, and anesthesia - in the substantia nigra and the primary motor cortex, two regions not previously studied in this context,” write the authors.

The team measured the sleep cycles of mice, comparing electrical brain activity and breathing and how the two timed off one another. They also assessed the mice during wakefulness, as well as under ketamine anesthesia.

The scientists found nuances and variations in all states. But one consistent thread was that the deepest non-REM sleep had breathing mostly independent of the brain waves, especially with the “slow delta” activity during the deepest part of slumber.

“The strength of respiration-neural coupling varied across multiple states, including NREM sleep, REM sleep, quiet wakefulness, and anesthesia, and was directly related to the delta power, a hallmark of NREM sleep,” write the authors.

The conclusions could pave the way into better understanding of how sleep works - and could help with some disease states, they find.

“These findings provide new insights into how internal brain states interact with peripheral rhythms like respiration, with important functional implications for both sleep and anesthesia,” write the scientists.

“Furthermore,” they add, “elucidating the mechanisms underlying respiration-neural coupling, especially within basal ganglia circuits, will shed light on the pathophysiology of conditions such as Parkinson’s disease, where both sleep and respiration are commonly disrupted.”

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