Sleep helps 'clean up' the brain

If you have ever had insomnia, you will know the feeling of being dull and dazed.

A study published in the April 3 issue of Science provides evidence of a vague feeling - the protein accumulated in the flies' brains loses sleep and the protein concentration decreases in flies resting fully. enough. This protein is located in synapses, a part of the neuron that allows brain cells to communicate with other neurons. Researchers at the University of Wisconsin-Madison School of Public Health believe it is a testament to the theory of 'synaptic regulation'. This is the idea that synapses will get better when we wake up because we are always learning and adapting to the environment, and sleep will make our synapses weak. This is important because larger synapses consume a lot of energy, take up a lot of space and need a lot of supplies, including the protein mentioned above.

Sleep - by allowing synaptic shrinkage - helps save energy, space and materials while cleaning unnecessary 'noises' from the previous day. From there, our brain will be ready to continue to load new information the next day.

Researchers - Giorgio Gilestro, Giulio Tononi and Chiara Cirelli of the Center for Sleep and Consciousness - discovered that the concentration of protein contains messages in synapses between neurons that reduce by 30 to 40% when sleeping .

In the Science article, three-dimensional images using the same focus microscope show that the brain of insomnia fruit flies is full of synaptic proteins, called Bruchpilot (BRP), a component of the brain system for allow neurons to communicate with each other. In fully rested flies, BRP levels and 4 other synaptic proteins returned to lower concentrations, suggesting that the brain restarted the brain to be able to acquire more knowledge and information on the day. the next day.

Cirelli, a professor of psychiatry, said: 'We know that sleep is essential for our brains to function normally, learn new things every day, and at the same time, in some schools. Combine what we collect in a day. When we sleep, we think that most, if not all, synapses are scaled down. At the end of sleep, the strongest synapse joints shrink, while the weakest synapse even disappears. '

Microscopic observation with the focus shows that this process takes place in the three main parts of the fruit fly's brain in relation to the ability to learn.

On the left, a fully rested brain has a high concentration of BRP protein. On the right, the brain of insomnia flies is orange in the BRP focus area. (Bruchpilot or BRP is a protein that keeps communication between neurons). In tired flies, this protein has a high concentration in the three main areas of the fly's brain related to the ability to learn. Sleep will reduce the concentration of this protein, meaning that the synapses are smaller and weaker. This cycle is called 'rearrangement', so that the brain is brought back to normal levels of neurological activity and begins to absorb knowledge the next day. (Photo: UW Health Public Affairs).

In the paper published last year, Tononi, Cirelli and co-authors discovered similar chemical changes in the synapses of rat brains. They also showed that the brains of mice had a stronger reaction to electrical stimulation after waking, and a weaker reaction after sleep. That finding provides additional evidence, using electrophysiological techniques rather than elemental techniques, consistent with the idea that synapses become stronger during the day, and weaker when sleeping. Because sleep functions similarly in different animals such as mice and fruit flies, Cirelli says this trait is evolved, and has important implications for the health and survival of a species. object.

The Wisconsin Laboratory is a pioneer in sleep research methods in different species, including fruit flies.

To keep the flies awake, the researchers put them in a 'stimulus' containing 10 discs, one containing 32 flies. A robotic arm occasionally shakes the plates to keep the flies awake.

The flies lose sleep for at least 24 hours. The researchers then tested their brains and measured the levels of four pre-synaptic proteins and one post-synaptic protein. Results showed that protein levels increased rapidly when flies awake and decreased after sleep. Other experiments confirmed that changes in protein levels are not caused by exposure to light and darkness or stimulation, but by sleep and wake. They also used confocal microscopy and antibodies that recognize BRP to determine the expression of this protein in different parts of the fruit fly.

Higher synaptic protein concentrations when awake can be a sign of random experiences stuffed into the brain every day, and need to be cleared to make room for learning and really important memories.

Cirelli said: 'Most of what we learn in a day, we don't really need to remember. If you use up all of the available space in your brain, you can't learn anything until you clear away unnecessary things. '

Refer:
Giorgio F. Gilestro, Giulio Tononi, and Chiara Cirelli.Widespread Changes in Synaptic Markers as a Sleep and Wakefulness function in Drosophila.Science, 2009;324 (5923): 109 DOI: 10.1126 / science.1166673