What quantum activity happens in the brain

Neuroresearch study : Life in the dead brain

Where is the line between life and death? A new study raises this question again. Researchers succeeded in restoring some cell activities in the brains of pigs that had been slaughtered four hours earlier.

Life, but not alive

The team around Nenad Sestan from the Yale School of Medicine in New Haven emphasizes in the journal "Nature" that there were no signs of perception or awareness. "From a clinical point of view, this is not a living brain, but a cellularly active brain," says study author Zvonimir Vrselja. German experts rate the work differently: "The line between life and death is not as clear as we have imagined it to be," says Bernd Böttiger, Director of the Clinic for Anaesthesiology and Operative Intensive Care Medicine at Cologne University Hospital. Mannheim medical lawyer Jochen Taupitz says the research results could "lead to intensive medical measures having to be taken longer than before."

Previously it was assumed that nerve cells without blood supply and oxygen die within minutes. But for a long time there have been doubts that this degeneration is actually complete and irreversible after just a few minutes. This is where the study began: the researchers obtained the heads of young pigs from a slaughterhouse and removed the brains. Four hours after the slaughter, they pumped a special solution through the main arteries with a specially developed machine. Six hours later, they found that some cell functions were still intact.

Metabolism, but not organized activity

They found isolated activity in synapses and metabolic processes, such as the consumption of oxygen and glucose. They also found that blood vessels still responded to certain substances.

“At no point have we observed any kind of organized electrical activity associated with perception or awareness,” Vrselja emphasizes. Nevertheless, the head of the study Sestan derives fundamental findings: "The intact brain of a healthy mammal still contains a previously underestimated ability to restore blood circulation and certain molecular and cellular activities several hours after a cardiac arrest."

Shifted border

For the time being, however, “such results are of no relevance for a person who experiences cardiovascular arrest on the street,” says Böttiger. This “still needs resuscitation measures as soon as possible.” Nevertheless, such experiments show “that the limit that we have set for the survival of brain cells is shifting - and that is a good thing.”

The results are also unlikely to have any impact on the definition of brain death, which is important for the removal of organs for organ donation. One of the reasons for this is that patients diagnosed as “brain dead” usually still have isolated cellular functions of the type described here. (rif, dpa, smc)

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