Ketamine Can Switch off the Brain in an Instant

A new study suggests that using ketamine could completely stop brain activity for a period of time. This discovery could have interesting applications for the future of anesthesia.



While a team of researchers was studying the patterns of brain activity in sheep with Huntington’s disease, they made an amazing discovery that could lead to a new understanding of the mechanisms of action of certain anesthetics. In this case, by administering ketamine, a substance first synthesized in 1962, they discovered a complete interruption of the brain activity of their subjects for several minutes, a phenomenon they believed had never been observed before.

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“It was not only a decrease in brain activity. After a high dose of ketamine, the sheep’s brain shut down completely. We’ve never seen this before,” says Jenny Morton of Cambridge University. A few minutes later the animal’s brain was functioning normally again. It was as if they were turned off and on again.” This surprising effect of ketamine was observed in the electroencephalographic readings collected by the researchers.

Several dosages were tested, between 3 mg/kg and 24 mg/kg, which is the maximum as an anesthetic and the minimum as a drug. The researchers were then surprised to discover that the brain activity of sheep systematically followed three different phases: sedation, dissociative anesthesia, and absence of voluntary movements, followed by a state of full consciousness and alertness without voluntary movements.

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At the highest dose, the researchers observed a complete interruption of the EEG in five of the six sheep tested, which occurred two minutes after the administration of the substance. However, the animals continued to breathe, indicating that some cortical areas were still active. “The brain is not dead or damaged,” Morton said.

Although the original study was mainly intended to analyze Huntington’s disease in sheep, the article published in the journal Nature focuses specifically on healthy sheep to further investigate this new observation, which may have important implications for humans. “Our goal was not really to observe the effects of ketamine, but to use it as a tool to study brain activity in sheep with and without the Huntington’s disease gene,” notes Morton. But our incredible discoveries could explain how ketamine works.

These results show how much we still have to learn about the effects of ketamine on the brain. This synthetic substance was approved for use by American soldiers in Vietnam once it was approved by the Food and Drug Administration (FDA) and is used as an analgesic and anesthetic.

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In recent years it has offered new opportunities for exploitation with more or less conclusive results in the fight against depression, post-traumatic stress, and migraines. It is also used illegally as a drug capable of inducing a catatonic state close to a near-death experience.

These new discoveries could not only lead to a better understanding of the mechanisms of action of ketamine as an anesthetic but also open up interesting avenues for research into its use in the fight against certain neurological and psychological disorders.


Characteristic patterns of EEG oscillations in sheep (Ovis aries) induced by ketamine may explain the psychotropic effects seen in humans



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