The fetus 'sleep cycle'

After about 7 months of development in the womb, a fetus spends most of his time sleeping. The fetal brain converts between sleep and rapid motion (REM) and a restful state with non-REM sleep (non-REM). But whether the brain of a younger fetus switches between different sleeping states or simply doesn't work, this remains a mystery to date.

Mathematician Karin Schwab and a group of neuroscientists at Friedrich Schiller University in Jena, Germany, discovered that the lamb fetus entered a dreamlike state a few weeks before the first eye movements were found that. Their analysis can bring a deeper understanding of the purpose of sleep activity. It also provides a tool to study brain development and identify the most dangerous crickets, when injury can lead to disease later.

The study appears in the special issue of Chaos magazine, published by the American Institute of Physics (AIP). This special number focuses on the nonlinear aspects of the cognitive and neurological systems. The issue also raises questions about the impact of fluctuations on certain areas of the brain, and suggests several methods for many problems in neuroscience - including sleep.

Direct measurement of brain activity of human fetuses is impossible. What we know about fetal sleep habits is mainly from observing eye movements. Around the 7th month during development, rapid eye movements begin to be noticed. Every 20 to 40 minutes, the brain of a developing fetus changes between sleeping fast-moving eyes, strong brain activity, and sleepless eyes, brain rest. The function of these cycles is still being actively discussed in sleep research circles.

Some people have tried to measure fetal brain activity when young by attaching to an EEG device. These measurements, according to Schwab, are difficult to implement and often contain many errors. So neuroscientists who study fetal brain development wonder whether the sleep cycle simply appears at a certain time, or whether it develops gradually from another form of brain activity.

After about 7 months of development in the womb, a fetus spends most of his time sleeping. The fetal brain converts between sleep and rapid motion (REM) and a restful state with non-REM sleep (non-REM). But whether the brain of a younger fetus switches between different sleeping states or simply doesn't work, this remains a mystery to date. (Photo: iStockphoto / Noel Powell)

To fill this gap, Schwab studied sheep and animals that usually have one to two fetuses that are similar in size and weight to human fetuses. The process of brain development in sheep is quite similar in humans, lasting 280 days in humans and 150 days in sheep. The researchers directly recorded the electroencephal activity of 106-day-old fetuses, something that never existed before.

Using complex analytical methods, Schwab discovered the cycle of brain activity when the fetus was still young. Unlike the later development cycles, these cycles fluctuate over a period of 5 to 10 minutes and slowly change as the fetus grows.

It is difficult to express what the fetus experiences in these circulatory cycles, but the discovery has brought new insights into the origin of sleep. Schwab said: 'Sleep does not suddenly develop from an inactive brain. Sleeping and changing sleep patterns are tightly controlled processes. ' These findings are also consistent with data showing that brain cells (neurons) produce a perfect sleep state earlier than the rest of the brain.

A better understanding of brain development may provide clues about future illnesses, such as neurological disorders or sudden death in children. Research also brings new insights into brain development. Circulatory changes in neural activity can stimulate other neurons to find and connect with each other to create complex networks in the brain. Complex analyzes of brain activity can help detect vulnerable stages in brain development.

Refer:
Schwab et al.Nonlinear analysis and modeling of cortical activation and deactivation patterns in the immature fetal electrocorticogram.Chaos An Interdisciplinary Journal of Nonlinear Science, 2009;19 (1): 015111 DOI: 10.1063 / 1.3100546