Why do people in space start to twitch their eyes?

(ORDO NEWS) — The people on the International Space Station are constantly in a state of weightlessness. It is very unusual for terrestrial organisms, so each person reacts to it in his own way. Astronauts who enter the ISS for the first time sometimes even develop space sickness. Their appetite decreases, dizziness, nausea and a host of other unpleasant symptoms occur.

One of the strangest consequences of being in zero gravity is nystagmus, which is the rapid and involuntary movement of the eyes. Scientists have not been able to explain the reason for this phenomenon for a long time, but recently they conducted an experiment, the results of which clarified a lot. As in many similar scientific works, the experiment was carried out on laboratory mice. Let’s find out what the experiment was and what interesting scientists managed to learn.

What is nystagmus?

Many astronauts who have been on board the space station have experienced vision problems. Most often, they suffered from swelling of the optic nerves, which makes it very difficult to monitor what is happening around. But there is also a stranger phenomenon called nystagmus. It is a set of rhythmic movements of the eyeball, which also prevent people from orienting themselves in space. There are many causes of nystagmus, and among them are brain damage, drug poisoning, and so on. But why does nystagmus often occur precisely during weightlessness? Scientists have almost found the answer to this question.

New experiment in space

This was done after conducting an experiment, the results of which were published in the scientific journal Brain Research. Regular readers of our site are already well aware that some animals from time to time are inside the ISS. Most often, such an opportunity falls out to mice – a couple of years ago I already said that astronauts watched the behavior of rodents in zero gravity. Mice also took part in the new scientific work. The essence of the experiment was that they simply lived on the ISS for 30 days, and then scientists studied the changes that took place in their bodies.

Previously, researchers have already found out that nystagmus occurs due to malfunctioning of the block or oculomotor nerves. The block nerve is responsible for the work of the superior oblique muscle, which rotates the eyeball outward and downward. The oculomotor nerve is also responsible for the movement of the eyeball, the lifting of the eyelid, and the reaction of the pupils to light. That is why the first thing the researchers wondered about was how weightlessness affects these nerves.

Eye twitching in space

Now attention – it will be a little difficult. Staying in zero gravity led to changes in the shape and location of dendrites of motoneurons in the trochlear nerve of mice. Dendrites are called branching processes that receive information from the surrounding nerve cells. And motor neurons are nerve cells that set muscles in motion. Ultimately, it turns out that nystagmus in zero gravity occurs due to a change in the shape and location of the branched processes near the eyes. Information about movements is transmitted incorrectly, which is why the eyes begin to make involuntary movements.

At the moment, the researchers believe that these changes are a necessary measure. The body always needs to get used to new conditions, so it tries to get as much data as possible about the environment. The experiment carried out filled the gap in knowledge about the causes of nystagmus in conditions of weightlessness. But scientists still do not know a lot about the effect of the absence of gravity on human organisms. So they will do many more experiments in the future.

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