(ESA)
The brains of astronauts who have spent about half a year in space suffer microstructural changes in the white matter that connects sensorimotor areas.
These changes in connections are still noticeable six months later.
The results support the concept of the learning brain, according to which the brain adapts to space flight through neuroplasticity
It reconfigures connections between sensorimotor centers to adapt movements in weightless conditions.
Space flight can seriously change both the functional connections and the microstructural organization of the brain.
For example, after returning from a long flight, astronauts experience an upward displacement of the brain inside the skull and physiological changes
Those changes include a decrease in the volume of gray and white matter, expansion of the ventricles, and an increase in the volume of cerebrospinal fluid.
Moreover, such effects, at least in part, persist after returning to Earth.
However, it is not known whether this is purely due to a mechanical effect on the brain (its displacement and an increase in the amount of cerebrospinal fluid that compress adjacent tissues), or to neuroplasticity (the property of the brain to change and adapt throughout life).
now scientists of the Institute of Biomedical Problems of the Russian Academy of Sciences (IMBP) and the European Space Agency studied the brains of astronauts after a long space flight.
From the Russian side, this study was led by Elena Tomilovskaya from the IMBP, from the European Space Agency, by Floris Wuyts from the University of Antwerp.
The study involved 12 astronauts who spent an average of 172 days on the International Space Station.
All participants underwent brain scans one to two months prior to spaceflight, then an average of ten days after returning to Earth, and a third time for only eight participants, an average of 230 days after returning from the space station.
To study the structure and function of the brain after spaceflight, the researchers used a brain imaging technique called tractography.
Tractography is based on diffuse MRI and allows you to visualize the system of cerebral pathways - the tracts that form the white matter of the brain.
The white matter mainly consists of bundles of axons, along which the nerve impulse runs from one nerve cell to another, from one area to another, which is why the white matter is called the brain pathway system.
In other words, tractography allows you to trace the pattern of connections between different areas within the brain.
The researchers found microstructural changes in pathways that link sensorimotor areas.
An astronaut under conditions of weightlessness has to restructure the ways of his movement in space in comparison with the Earth.
This affects the network of connections between sensorimotor centers that provide representation, movement and control of the brain over the body.
That is, in the new conditions, the brain seems to be rebuilt. And this transformation of connections is still noticeable six months later.
The fact that sensorimotor areas adapt after space flight was previously known, but now it is clear that this also happens at the level of connections between these areas.
Together, these data support the so-called learning brain hypothesis, according to which the brain adapts to space flight through neuroplasticity, the authors believe.
The scientists also noted changes in the corpus callosum, the central pathway that connects the two hemispheres.
These results are most likely due to anatomical shifts in the brain or increased volumes of cerebrospinal fluid circulating in the ventricles rather than neuroplasticity.
Given that the corpus callosum is less voluminous than most other parts of the brain, it may be more susceptible to deformity caused by this set of anatomical changes.
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