When he went to live in space for half a year, the astronaut's brain was squeezed and the circuit inside changed.

In space, due to the lack of force, even hair can fly in all directions.

But why is the brain squeezed?

Living on the earth, there is probably no kind of animal that is not subject to gravity.

Humans are no exception.

The skeletons in our bodies are created under the strict constraints of gravity.

Like building a house, if the structure is not strong enough, the building can be easily destroyed by gravity.

It's not just the human skeleton, but every cell we have is affected by gravity.

Some studies have suggested that one of the main reasons why a cell is so small is that gravity limits its size: the smaller the cell is, the more negligible the effect of gravity is, but if it is large enough, a more complex cytoskeleton may be needed. to keep the whole cell from being destroyed.

It sounds like gravity makes life difficult.

But the fact that all kinds of animals can thrive on such a planet means that we have evolved into a version adapted to gravity.

In this way, it is a weightlessness environment, which is more likely to cause harm to the body.

It may not hurt to ride a roller coaster once in a while, but if you leave the earth to live in a spaceship for the first half of the year, as astronauts do, the changes in the body cannot be ignored.

With regard to the impact of space travel, apart from osteoporosis, changes in the brain are probably the most frequently mentioned.

Recently, an international team of researchers found that the neural connections of the brain did change significantly in humans who had traveled for a long time in space.

Be squeezed out of shape.

On earth, we can always feel the pull of gravity, and even if we get on a plane to an altitude of 10,000 meters, we are unlikely to float in the cabin-jump up and fall.

But when the astronaut's spacecraft, driven by a rocket, rushes into space at the first cosmic speed, it can fly around the earth without immediately falling.

Spacecraft fly around the earth, astronauts also fly around the earth, gravity is used to maintain orbit, so it is difficult for astronauts to feel the force pulling themselves, so they enter a state of "weightlessness".

However, no matter how close it is, the gravity felt by astronauts and spacecraft is not completely zero, or the influence of gravity on people and objects in space is not zero, but very small.

In fact, astronauts are in a "microgravity" environment.

In the absence of restraint, even a drop of water will show a different appearance from that of the earth, turning into a ball and floating in the air.

There is also a lot of liquid in the human body. under normal gravity conditions, the liquid flows naturally downward, but the microgravity environment will prevent some fluid from flowing to the lower limbs, allowing the fluid to be redistributed all over the body.

One possible result is that more fluid flows to the brain.

In the past, scientists have found that the volume of cerebrospinal fluid (CSF) of astronauts who return to Earth after living in space for six months has increased.

Cerebrospinal fluid (CSF) is the fluid that flows in the hollow space of the brain and spinal cord, which surrounds and protects it.

However, the research at that time did not go deep into the level of neural connections.

Now new research suggests that it is the redistribution of these fluids that changes some neural connections in the brain.

A group of scientists observed 12 Russian astronauts through a collaborative project between the European Space Agency and the Russian Federal Space Agency: all of them had experienced a long space trip, with an average of 172 days, or nearly six months.

The team used a technique called fiber tracer imaging (fiber tractography), which reconstructs 3D images based on data provided by diffusion magnetic resonance imaging (dMRI), which contains a variety of nerve bundles so that scientists can see if the "wiring" in the brain has changed.

To this end, the researchers took measurements before the astronauts set off for space, 10 days after returning to Earth, and seven months after returning to Earth.

At first, they only observed a change in the shape of the corpus callosum (corpus callosum) in the astronauts' brains.

The corpus callosum is a large bundle of nerve fibers, like the "central highway" that connects the left and right hemispheres.

At first, scientists thought that structural changes in the corpus callosum itself caused the deformation.

But then the team noticed the brain ventricles adjacent to the corpus callosum: after returning from space, the astronauts' ventricles dilated.

The ventricle is the space for the production and storage of cerebrospinal fluid, filled with fluid, and has become larger than ever as a result of being in space.

Scientists believe that it is the expansion of the ventricle that causes microstructure changes in the adjacent nerve tissue, the corpus callosum.

Of course, the corpus callosum is not the only deformed nerve bundle.

Scientists have also observed that some nerve bundles related to sensorimotor, such as corticopontine tract (corticopontine tract) and corticospinal tract (corticospinal tract), have also undergone microstructure changes before and after space travel.

Sensorimotor (sensorimotor) refers to a series of activities in which a stimulus acts on the sensory nerve, spreads to the brain, and then sends out action instructions by the motor nerve.

Many of the sensorimotor bundles that change during space travel are also connected to the cerebellum, which is responsible for motor control.

The observations also convinced scientists that the astronauts' brains had been "rewired".

Although seven months after returning to Earth, some structural changes in nerve tissue, such as the deformation of the corpus callosum, have gradually recovered.

However, some changes can still be observed.

In the control group that had not been to space, no similar changes were found, so the factor of natural aging was excluded.

The brain will also move up.

Although, this is the first time that researchers have actually observed changes in the brains of astronauts at the level of neural connections.

But it is not the first time that humans have experienced the destructive power of microgravity to the human brain.

More than half of the astronauts who have worked on the International Space Station have suffered from visual impairment after returning to Earth.

Scientists call it space flight-related neurovisual syndrome (Space flight-associated Neuro-ocular Syndrome,SANS), which is related to optic nerve swelling, retinal hemorrhage, retinal leukoplakia and so on.