September 22, 2023

Zapping a rodent’s brain can put it into suspended animation. Scientists want to one day use the same technique for humans traveling to Mars.

An artist's impression shows a kneeling astronaut on Mars with a rocket in the background.  The landscape is barren and dusty.

An artist’s impression of what an astronaut on Mars might look like.peepo/Getty Images

  • Scientists have put mice and rats into a floating animation-like state called torpor.

  • The condition was caused by beaming ultrasound waves to a precise spot in the rodent’s brain.

  • This technique could one day be used on humans for aerospace and medical purposes.

Scientists have managed to put mice and rats to sleep using ultrasound, bringing them one step closer to finding a way to induce suspended animation in humans.

Space agencies such as NASA and the European Space Agency (ESA) eagerly await the science of artificially inducing sedation or hibernation-like states in animals.

They hope this could one day save on energy and costs of long-distance space travel to planets like Mars.

The latest study, published in the peer-reviewed journal Nature Metabolism, found that researchers were able to induce anesthesia in mice and rats using ultrasound waves aimed at a precise part of the animals’ brains.

“If successfully demonstrated in humans, this technology has significant potential for medical applications, particularly in life-threatening conditions such as strokes and heart attacks,” lead study author Hong Chen, a professor of biomedical engineering at Washington University, told Live Science. com.

“We can envision astronauts wearing a helmet-like device designed to target the hypothalamus to induce a state of anesthesia,” she said.

Tiny helmets zap the rodents’ brains

Torpor is a state of suspended animation where animals may look like they are going to sleep, but in fact drastically reduce their metabolic activity, usually in response to extremely adverse conditions.

Scientists had previously discovered that anesthesia can be produced by injecting a chemical into a precise part of the brain that controls the central nervous system. But Chen and colleagues were interested to see if there was a non-invasive way to induce that state, without physically breaching the skull.

Mice and rats were given tiny helmets to send ultrasound waves to the brain. The scientists noted that these waves could effectively push the rodents into a state of stupor.

A series of images shows experimental results of the study.  The panels show the temperature of the mouse immediately after and 13 minutes after stimulation with the ultrasounds.  The temperature of the mouse drops visibly after 13 minutes during the exercise.

Experimental results show mouse temperature three minutes and 13 minutes after probe stimulation. The top panel shows that the mouse’s body temperature drops visibly. In this photo, “VS” means “ultrasound” and BAT means “brown adipose tissue” (here means back fat).Yang, Y., Yuan, J., Field, R. L. et al. Nat Metab 5, 789-803 (2023).

About an hour after the ultrasound pulse, the mice’s body temperature and metabolism dropped, a state similar to anesthesia in nature. The mice’s average body temperature dropped to 3.5 degrees Celsius, and their heart rate and oxygen consumption also dropped.

The rats’ body temperatures also dropped, albeit to a lower level, to 3.57 F (2 C).

The fact that this state was induced in rats is encouraging, as these rodents “don’t naturally go to sleep, suggesting the possibility that similar effects could be induced in humans,” the scientists said in the study.

This technology could one day be used to make space travel more economical


Artist’s concept of a Mars-ready habitatSpaceWorks Entrepreneurial

Space agencies keep a close eye on this kind of research. If they could crack the science of suspended animation, space travel could become safer and cheaper, especially for long-haul flights like the 16-month round trip to Mars.

A single astronaut eats about 30 kilograms (66 pounds) of food and water a week, but their consumption could drop by 75% in suspended animation, according to the BBC. Astronauts would also need a lot less room to roam, so the rocket wouldn’t need crew quarters.

Taken together, these cuts could save several tons of mass, a crucial savings when every pound adds weight to an already hefty rocket, ESA found in a 2019 study.

Inducing a hibernation-like state also has health benefits. Studies suggest that astronauts are less at risk of significant loss of muscle and bone density and are protected from the worst effects of cosmic ray exposure. It could also protect the astronauts’ mental health, as no one knows what happens to human minds after being away from Earth for so long.

Hibernating in space would be “not nearly as extreme as what we see in the movies,” John Bradford, president and CTO of SpaceWorks Enterprises, previously told CNET. Spaceworks received several rounds of funding from NASA in 2016 to develop a space sleep concept.

For Spaceworks, astronauts would be sedated for 14 days at a time and awakened for three or four days. That way there would always be an active astronaut on shift to monitor progress.

Scientists are getting closer, but not quite there yet

brown bear pushes face through snowy shore

Bears are other animals that naturally go into a stupor.Kaisa Siren/Lehtikuva/Reuters

The rapid progress in basic science supporting this innovation is encouraging.

One way to induce suspended animation is to dramatically cool the body. In fact, surgeons already use deep hypothermia – cooling body temperature below 35 degrees Celsius – to stop blood during particularly tricky heart surgeries, even though this has to take more than 20 to 30 minutes.

Other studies, such as this recent one, suggest hacking the brain’s sleeping anesthetic mechanism to induce this state. Previous studies had suggested drug-induced anesthesia, but the advantage of the approach in this recent study is that it is noninvasive, accurate and safe, scientists said in the study.

“As far as we know, there’s nothing unique about it homo sapiens that would prevent our species from hibernating, and I believe the capacity is there, but it needs to be unlocked,” Vladyslav Vyazovskiy, professor of sleep physiology at Oxford University, told the BBC.

“For me, the real question is not whether we can hibernate, but how… How do neurons in the hypothalamus know it’s time to hibernate? Who tells them? This is the real question,” he said.

Nevertheless, most research on prolonged suspended animation is still only done on animals, and we’re probably a long way from testing it on humans.

“Further research is still needed to determine the safety and feasibility of this approach in humans,” Chen told Live Science.

Read the original article on Business Insider

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