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NASA astronaut Randy Bresnik works with the bioreactor bags containing lung tissue samples within the Microgravity Science Glovebox aboard the space station. The culture fluid will need to be frozen and returned to Earth for analysis. Photo: NASA

Homo sapiens, like all of Earth’s species, evolved with a defined set of planetary rules, including the constant pull of gravity downward on the body.

It now seems that human bodies out in the unmoored weightlessness of space start developing anatomical anomalies – including the movement of key neurological features in the brain and spine, reports a team of scientists from the Medical University of South Carolina in the New England Journal of Medicine.

“We observed an upward shift of the brain, narrowing of the central sulcus, and narrowing of cerebrospinal fluid spaces at the vertex in most of the astronauts in this study who had had long-duration flights,” they write.

The phenomenon is a new view into the brains of the extraplanetary explorers. Previous research based on detailed MRIs showed decreased brain volume in the frontotemporal gray matter from astronauts who had taken spaceflights. NASA has acknowledged some of the effects on the long-term astronauts, dubbing the changes as “visual impairment and intracranial pressure,” or VIIP, syndrome.

The current study involved 34 astronauts who were scanned with MRIs before and after trips beyond Earth’s gravitational pull. Eighteen of them underwent long-duration flights, and 16 had trips that were of shorter duration.

Seventeen of the long-duration astronauts, and three of 16 from the short-term group, had narrowing of the central sulcus, the brain area separating the parietal and frontal lobes.

All the long-duration astronauts showed nothing less than “an upward shift of the brain” – and also narrowing of all cerebrospinal fluid spaces, they add. Three of the astronauts had optic-disc edema, a swelling of the eye area.

“One explanation for these findings is upward displacement of the cerebral hemispheres and concurrent ventricular enlargement,” they write. “It is also possible that an increase in the volume of the sensorimotor cortex, previously reported in astronauts, contributed to narrowing of the central sulcus.”

The connection between these shifts and movements and the VIIP Syndrome is not yet fully clear, they add. However, that link needs to be better understood for humankind to take its next steps beyond Earth’s embrace.

“Determining the cause of the VIIP syndrome will be important in planning longer-duration spaceflights, such as a crewed mission to Mars,” they write.

Even as NASA and other space agencies continue to plan for the next steps to get humans out into the solar system, the logistics have been daunting. For instance, a UC Irvine study two years ago found that long-term space travel would bombard astronauts’ brains with cosmic rays that could cause irreparable harm.

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