After the recent historical launch of NASA astronauts in Space X Crew Dragon spaceship, the ambitious murmurs of Mars colonization and Space exploration that has been brewing for a few years seem nearer than ever before. Technical constraints aside, another major reason why these goals seemed so far-fetched and unattainable was because of our inherent biological limitations. As a species evolved to survive on Earth, how is the foreign atmosphere of Mars and Space going to treat us?
This is a broad question, there are so many aspects of space or Mars that can affect so many different parts of our biological system. However, I was really curious about how microgravity (an extremely weak gravity) conditions of Mars (0.3g) and on orbiting spacecraft affects our Brain. So that’s what I’ll be talking about in this post!
Physical effects
1. White matter volume
Firstly, it seems as though there is as much a 6% increase in white matter volume in astronauts as a result of space travel. The problem is that all this extra white matter seems to cause the brain to fill with fluid, although the research team that reported on this aren’t too sure of why exactly that is so. However, a major suspect is the “dysfunction of water transport in microgravity”. This is a major problem, not only for the brain, but also for all other biological function. This is why Astronauts observe puffy faces, or ‘chicken leg’ symptoms. But the movement of fluid to the brain due to the lowered gravity means that there is high inter-cranial pressure and explains some symptoms that astronauts observe such as bloodshot eyes or blurry vision. This increased white matter volume that persists even after astronauts return to earth mean that such symptoms of high inter-cranial pressures also persist upon return to earth.
2. Brain Connectivity
Another interesting physical change observed as a result of microgravity is a change in brain connectivity related to perception and movement.
Firstly, there seems to be decreased connectivity between cerebral cortex and vestibular nuclei. The vestibular nuclei codes for information coming from the vestibular system which is a sensory system responsible for motion, head position and spatial orientation. It helps us balance, stabilize our heads and body movements and hold our postures. As such, it seems as though, in space, information from the vestibular system is deprioritized.
Secondly, there seems to be an increased connectivity between insular cortexes. Insular cortexes are responsible for the integration of sensory inputs form various sensory systems. Another region of the brain that performs similar functions: parietal cortex, also showed increased connectivity.
Both of these results seem to indicate that astronauts become better at taking in input from other senses in a situation (such as in microgravity) where we don’t seem to be able to trust some of our senses.
Cognitive functions
1. Decision Making
A research indicated that people are less prone to making novel decisions (steering form routine in a way) in microgravity situation. This is quite an important result because astronauts are in high stakes situations navigating extremely unfamiliar atmospheres. An impaired ability to make novel decisions can be quite devastating in such circumstances.
2. Nitric Oxide and Cognitive impairment
Another interesting research discusses how microgravity situations create high concentrations of nitric oxide in the bloodstream that results in certain parts of the brain receiving too much blood, causes parts of the brain to not receive oxygen fast enough. This lack of oxygen can result in various cognitive facilities such as thinking, reasoning, etc.
Action
Perhaps the most interesting finding I discovered was the effect of microgravity on action. This involved a couple of astronauts playing catch with a ball in which the ball was launched at them through a spring-loaded cannon at a constant speed (instead of with constant acceleration like on earth). While in microgravity conditions, these astronauts reacted to catching the ball (muscle contraction and arm movements) too early. Interesting, it wasn’t just randomly early but as they reacted as if the ball was traveling on normal Earth gravity (1g) conditions. Even after fifteen days of staying in the microgravity conditions, this reaction persisted (whereas other effects such as motion sickness fade within two to three days). This is pretty cool because of what it seems to reveal. As corroborated by Neuroscientist Joe McIntyre, there seems to be an inherent model of gravity in our brains. I suppose it is not too surprising of a finding, given that we did evolve to survive on earth conditions. Regardless, it’s pretty cool.
In conclusion, microgravity does seem to have pretty serious effects on our brains, from liquid transportation problems to cognitive changes. But on that note, some exciting new countermeasures that are being worked on to mitigate such problems include artificial gravity, rubber suction trousers that can create negative body pressure (to “pull” the fluid/blood accumulated at the brain away from it), and drugs to decrease nitric oxide levels. It’ll definitely be exciting to see how these new technologies and measures would accelerate the current course toward broader space exploration.
Till my next post,
See ya!
References
https://science.nasa.gov/science-news/science-at-nasa/2002/18mar_playingcatch
https://theconversation.com/what-happens-to-the-brain-in-zero-gravity-106256
https://medicalxpress.com/news/2019-08-microgravity-brain.html
https://www.theregister.com/2020/04/15/astronaut_brain_matter/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5610662/
https://www.sciencealert.com/exposure-to-zero-gravity-can-change-how-human-make-decisions
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