Monkey Experiment Reveals Brain Switch That Could Be Useful For Space Travel: ScienceAlert

For humans to ever venture among the stars, we will have to solve some major logistical problems.

Not the least of which is the travel time involved. Space is so vast and human technology so limited that the time it would take to travel to another star presents a significant barrier.

The Voyager 1 probe, for example, would take 73,000 years to reach Proxima Centauri, the closest star to the Sun, at its current speed.

Voyager was launched more than 40 years ago, and newer spacecraft might be expected to travel faster; even so, the journey would still take thousands of years with our current technology.

One potential solution would be generation ships, which would see multiple generations of space travelers live and die before reaching their final destination. Another would be artificial hibernation, if it could be successfully implemented.

This is what scientists from the Shenzhen Institute of Advanced Technology (SIAT) of the Chinese Academy of Sciences have begun to investigate; not in humans, but in monkeys, chemically causing a state of hypothermia.

“Here, we show that activation of a subpopulation of preoptic area (POA) neurons using a chemogenetic strategy reliably induces hypothermia in anesthetized and freely moving macaques.” the researchers write in their paper.

“Together, our findings demonstrate the central regulation of body temperature in primates and pave the way for future application in clinical practice.”

Hibernation and its slightly less comatose state, torpor, are physiological states that allow animals to withstand adverse conditions, such as extreme cold and low oxygen levels.

Body temperature drops and metabolism slows to a crawl, keeping the body in a simple “maintenance mode”—the bare minimum needed to stay alive while prevent atrophy.

This can be found in several animals, including warm-blooded mammals, but very few primates. Neuroscientists Wang Hong and Dai Ji from SIAT wanted to see if they could artificially induce a state of hypometabolism, or even hibernation, in primates by chemically manipulating neurons in the hypothalamus responsible for sleep and thermoregulation processes: the preoptic neurons .

The research was conducted on three male crab-eating monkeys (Macaca fascicularis). In both anesthetized and unanesthetized states, the researchers applied drugs designed to activate specific modified receptors in the brain, known as designer receptors activated exclusively by designer drugs, or DREADD.

The scientists then studied the results using functionals magnetic resonance imagingbehavioral changes and physiological and biochemical changes.

“To investigate the brain-wide network resulting from activation of the preoptic area (POA), we performed fMRI scans and identified multiple regions involved in thermoregulation and interoception,” says Dai.

“This is the first fMRI study to investigate the functional connections across the brain revealed by chemogenetic activation.”

The researchers found that a synthetic drug called clozapine N-oxide (CNO) reliably induced hypothermia in both the anesthetized and awake states in macaques.

However, in anesthetized monkeys, CNO-induced hypothermia caused a drop in core body temperature, preventing external heating. The researchers say this demonstrates the critical role POA neurons play in thermoregulation in primates.

The researchers recorded behavioral changes in the awake monkeys and compared them to those of mice with induced hypothermia. Normally, mice become less active and their heart rate lowers in an attempt to conserve heat.

The monkeys, on the other hand, showed an increase in heart rate and activity level and also began to tremble. This suggests that thermoregulation in primates is more complex than in mice; hibernation in humans (if it can be done at all) will have to be taken into account.

“This work provides the first successful demonstration of hypothermia in a primate based on targeted neural manipulation,” says Wang.

“With the growing passion for human spaceflight, this hypothermic monkey model is a milestone on the long road to artificial hibernation.”

The research was published in Innovation.