Scientists at the Research Institute of Molecular Pathology (IMP) in Vienna, studied the fundamental aspects of sleep in roundworms. They controlled the activity of nerve cells in the brain during sleep and wakefulness. Science journal publishes the results of this week.
Sleep - a universal trait in animals: each nerve system on a regular basis requires a state of relaxation, during which dramatically changes the brain activity. Sleep is vitally important, but scientists still argue why this is so.
The team of neuroscientists led by Manuel Zimmer used the roundworm C. elegans, to study in detail how the brain switches between wakefulness and sleep. The results show that animals sleep - a basic condition of the brain, while the lack of strong external stimuli environment.
C. elegans as a model selected sleep study because their nervous system is made up of 302 neurons and allows access to the activity of nerve cells in the brain. Scientists have observed the processes that the brain experiences between waking and sleeping.
The problem faced by the researchers was to control when the worms sleep and wake up. Annika Nichols and Tomas Eichler established experimental system using variable concentrations of oxygen as a switch. The natural habitat of C. elegans live in the soil, where abundant microorganisms maintain low levels of oxygen. Researchers have shown that in these conditions the worms feel comfortable and can sleep. Nichols and Eichler found that the fresh air with the atmospheric oxygen content disturbs the sleeping animals, causing them to wake up.
Nichols has recorded the activity of neurons in the brain when switching between sleep and wakefulness. She found that during sleep the majority of nerve cells, vigorously active during wakefulness, "fall asleep." However, several types of nerve cells, called RIS are active. Nichols showed that RIS increased activity in awake animals.
Watching the brain work when falling asleep, Nichols made an interesting discovery: Computer analysis showed that the neural network activity spontaneously becomes calm and stable state. Initially, the researchers suggested that the RIS cells leave the nervous system alone. However, the new data show that the RIS is more like an intermediary who "carries on negotiations between the players." Changes between waking and sleeping are caused by changes in the brain of some regulators.
Despite the many differences between the worm's brain and the human brain, these results provide a model for studying the fundamental principles of the human brain.