Nine electrodes are implanted in nine heads - one for each. Potassium chloride injection causes cardiac arrest. Blood no longer feeds the brain, and it rapidly begins to lack oxygen and glucose. Eternal martyrs of the mouse fall into a state of clinical death, once again dying for the sake of science.
This eerie experiment was conceived as an attempt to scientifically define the phenomenon of clinical death. Statistics indicate that 20%, that is, one in five patients who have experienced cardiac arrest, shares their impressions of the unusually vivid mystical experience that he was able to experience. In the stories, there are references to leaving your own body, visions of other worlds, and even a dark tunnel with a dazzling light at the end.
What is it? Brain fiction or real life after death? Jimo Borjigin became interested in this phenomenon when she studied the changes in hormone levels during the death of rodents due to a violation of the blood supply to the brain (essentially a stroke). She and her colleagues conducted a new experiment: they inserted electrodes in nine mice to measure the activity of six different areas of the brain.
In order not to torture the animals too much, the researchers used anesthesia, which changed the state of the rodents for an hour. After that, a lethal dose of potassium chloride was injected into their hearts, which led to the arrest of a vital organ.
In the 30 seconds that elapsed between the last heartbeat and the last appearance of signals in the brain, the researchers recorded the work of neurons. The oscillation frequency of the signals was in the range from 25 to 55 Hz. Interestingly, against the background of a general weakening after cardiac arrest, these signals increased. In addition, different parts of the brain synchronized these "rhythms" (and even better than when the animal was conscious).
Later, scientists were forced to state that these fluctuations are a gamma rhythm. It is customary to associate this rhythm with a person's conscious activity and his ability to concentrate his attention. Therefore, the presence of the gamma rhythm in mice at the time of cardiac arrest was a surprise to specialists. It turns out that after a cardiac arrest, the brain is hyperactive, information is processed, consciousness is enhanced.
“It's impressive to have such high brain activity in animals suffering from death throes,” said Christof Koch, who was not involved in the work, of the Allen Institute for Brain Science. "However, the result raises more questions than answers."
Dr. Koch has extensive experience in neuroscience and consciousness studies. According to the scientist, he is not inclined to equate the fixed gamma rhythm with "high consciousness" in rodents. In his opinion, the work does not fully take into account secondary factors such as the effect of anesthesia on the experimental subjects and other things. Other experts also point out that although mice are used as model organisms for humans, they are not suitable as models for dying visions.
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Despite the criticism, the authors of the experiment insist that clinical death is only a vivid illusion generated by human consciousness.
The researchers will continue their work, hoping that it will help not only fully understand the phenomenon of clinical death, but also identify ways to improve brain blood flow in emergency situations or prolong brain activity without causing irreparable harm to the patient's health.