Findings combine sound sleep with brainwave explosions that mathematically mimic earthquakes.
Recent studies in rats show that cortical excitement and short awakening during sleep have imbalance dynamics and complex organization across time scales. Necessary for spontaneous sleep-state transitions and for maintaining healthy sleep. Prof. Plamen Ch. Ivanov of Boston University and colleagues present these findings in PLOS Computational Biology .
Sleep is traditionally considered a homeostatic process that resists deviations from balance. In this regard, short waking phases are considered disorders that lead to sleep fragmentation and associated sleep disorders. While the homeostatic paradigm addresses aspects of sleep regulation associated with consolidated sleep and wakefulness and the sleep-wake cycle, it does not take into account the dozens of abrupt sleep-state transitions and microstates within sleep stages during the night. Ivanov and colleagues hypothesized that although sleep is homeostatic on timescales of hours and days, non-equilibrium dynamics and criticality underlie the microarchitecture of sleep on shorter time scales.
To test this hypothesis, the researchers collected the electroencephalogram (EEG). Recording of brain activity over several days in normal rats and in rats with parafacial zone injury, a brain region that contributes to the regulation of sleep. They analyzed the explosive dynamics of brain activity patterns, known as theta waves and delta waves, which occur in both sleeping rats and humans.
Their empirical findings and models suggest that sleep deprivation expresses an intrinsic non-equilibrium sleep regulatory mechanism related to the self-assembly of neuronal assemblies. This mechanism works on time scales of seconds and minutes and remains on the right path via continuous impulses in the brainwave rhythm.
The study also suggests that maintaining a non-compensatory condition is essential for the flexibility of the sleep regulation system to spontaneously activate multiple elements, transitions between different sleep stages and between sleep and wakefulness throughout the sleep period. Such a critical state is also required for the complex sleep microarchitecture, which is increasingly recognized as characteristic of healthy sleep. The observed sleep critical behavior is parallels to other imbalance systems such as earthquakes.
"Paradoxically, we find that the & # 39; hibernation & # 39; Healthy sleep is sustained by outbreaks of cortical rhythm activity, which temporally similarly obey organization, statistics and mathematical laws as earthquakes, "says Ivanov. "Our findings serve as building blocks for a better understanding of sleep and could help to better recognize and treat sleep disorders."
Reference: "Non-equilibrium critical dynamics of bursts in θ and δ rhythms as fundamental to sleep and wake microarchitecture" by Jilin WJL Wang, Fabrizio Lombardi, Xiyun Zhang, Christelle Anaclet and Plamen Ch. Ivanov, November 14, 2019, PLOS Computational Biology .
DOI: 10.1371 / journal.pcbi.1007268