Scientists at the University of Washington reported that using pulses of ultrasound acting on the brain, it is possible to put mice into a state of hibernation. The results of the study are published in the journal Nature Metabolism.

The work is based on the discovery of specific populations of neurons in an area of the brain called the hypothalamic preoptic area (POA). These cells act as a switch to "numbness," an energy-saving state that serves as a defense against adverse conditions such as starvation or cold.

In previous studies, scientists have made genetic changes to POA neurons so that they can fire when exposed to light or in the presence of certain chemicals. As a result, experimenters could make experimental mice fall into a stupor even under favorable conditions. The new study is based on the fact that POA neurons in the brain have TRPM2 ion channel proteins, which are known to change their structure in response to ultrasonic waves.

Miniature speakers were placed on the heads of the rodents to focus 3.2 megahertz waves into the preoptic region of the hypothalamus. During the experiment, the body temperature of the animals dropped by about three degrees Celsius. Heat has been redirected to the tails, which is a classic sign of torpor. Heart rate and metabolism also slowed down. By applying pulses of ultrasound every time the body temperature began to rise, the scientists were able to keep the mice in a state of hibernation for up to 24 hours. When the speakers were turned off, the animals returned to normal without any health effects.

An experiment on 12 rats that do not go into torpor in response to cold or lack of food showed a similar effect, although their body temperature dropped by only 1-2 degrees Celsius. The result suggests that the method can even work in animals that don't normally hibernate. However, a number of scientists are skeptical about the demonstrated effect, believing that this method will not work for people who have a larger brain and deeper POV.