Space: The Final Frontier

The female brain is seemingly unaffected by galactic cosmic radiation


Photo by Nancy Sterrett

My first introduction to space travel was in Zenon: Z3 when Zenon Kar saved Earth from the moon goddess, Selena. Ever since, I've been sort of obsessed with space travel, but astrophysics just doesn’t do it for me. You probably already know the basic hazards—no oxygen, no gravity and no way to grow food. This is all before you even get to the moon—past the moon is where things start to get crazy. So you can imagine the journey to Mars to be a bumpy one. 

Putting a human on Mars comes with a whole host of problems. Some technological, some temporal—but the most important having to do with all of the variables that come with having humans in space. Astronauts would have to spend between six to eight months confined to the spaceship, leading to mental problems from isolation and confinement. Group dynamics become strained, signaling the first rumblings of the chaos volcano erupting. 

But the astronauts don’t just have to deal with tense interactions with coworkers, they have to deal with their brains fighting back against the galaxy. Once you escape Earth’s gravitational field, there is the danger of the “floating brain.” This is basically your brain being pushed up into the skull. Research here in South Carolina by Dr. Donna Roberts at MUSC showed that the brain shifted towards the top of the skull, leading to the “floating brain” phenomenon which has some serious repercussions, one important one being the loss of vision due to a vast increase in intracranial pressure, swelling the optic nerve. 

Once you pass the moon, the galaxy is even less welcoming and a new foe awaits. The danger of cosmic radiation is less-known to the public, but presents one of the biggest hurdles for space travel. Cosmic radiation has a tremendous negative impact on the body, but its most visible effects are on the brain. Prolonged exposure would cause a dramatic decline in cognition, even leading up to dementia, not mentioning an increased risk for certain cancers. 

New studies have shown that there might be a sliver of hope after all—not in putting a man on Mars, but possibly a woman.  

Dr. Susanna Rosi’s lab at UC San Francisco found that the female mouse brain could be immune to the negative effects of cosmic radiation, which has implications for how humans would respond in this environment on the way to Mars. They studied mice after being exposed to simulated cosmic radiation and saw the male mice experience extreme declines in brain functioning. They had trouble interacting with other mice, identifying objects and saw a reduction in the number of neurotransmitter receptors and synaptic connections in the hippocampus—brain’s memory center.  But the female mice were fine. They did not show any signs of cognitive decline, had no problems interacting or see a decline in connections or receptors. 

Underlying female immunity to simulated cosmic radiation are the activity of the microglia, immunity cells in the brain that act to protect the brain from itself by eating dead neurons and other cellular debris. These cells have been shown to be fundamentally different between females and males and this is thought to be the reason why female mice showed immunity to cosmic radiation. 

I talked with Dr. Susanna Rosi, the lab’s director, to understand the implications this finding could have on the future of space travel. Dr. Rosi explains that the microglia in the male brain are in an “proinflammatory state” so once the brain starts to get zapped by the cosmos, the cells go into overdrive resulting in a lot of unnecessary deletions, leading to cognitive decline. Whereas these cells are in a more protective state in the female brain and respond better, or are not susceptible to, the injuries caused from the radiation. 

One could ask why this research in mice is important when considering how cosmic radiation could affect humans. But it is important to remember that you cannot test how cosmic radiation affects humans ethically. Studies on the effect of radiation on the body comes from studies of cancer patients undergoing chemo, but this is not the same type of radiation that astronauts would be exposed to. Dr. Rosi stresses that the only test for the effects of cosmic radiation is the real test, when we finally get a human on Mars. 

This research, however, is not the be-all and end-all. There are so many other factors that play a role in space travel so far into the galaxy, and cosmic radiation is only a piece of the puzzle. Dr. Rosi believes that it is important to consider as many factors as possible in this research and NASA has granted them the opportunity to continue their work to further understand the differences between the male and female brain; in addition to the effects of space travel overall on the brain. Going forward, they will test the compounding effects of social isolation, cosmic radiation and microgravity on the brain to build a risk assessment model for astronauts. 

But the future is looking bright (and female). NASA’s 2017 class of astronauts was 40% female and if the female immunity theory holds true, these numbers could change. Because, as Dr. Rosi says going to Mars “is not a matter of if, is a matter of when.” And this research could answer the question of who will be the first person to step foot on Mars.  

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