Comparing the impacts of propofol and ketamine on the brain

One 10 ml vial of 1000 mg ketamine. Credit: Psychonaught/Wikipedia

When a group of scientists from Indiana University examined the effects of the medicines propofol and ketamine on the brains of macaques, they discovered that they were more similar to what occurs when people take these drugs. Following the administration of propofol and ketamine to two macaques, the researchers published their findings in the journal Royal Society Open Science. The electrical activity recorded from the cerebral cortex of the macaques is described in detail.

The substance ketamine has been in the headlines a lot lately because of its growing popularity as an illegal drug. People who use it report experiencing dissociative, dreamy states, and hallucinations as a result of using it. In the past, ketamine was used as an anesthetic for both human and animal patients, leading to its present status as a popular party drug. However, since propofol was shown to be a superior alternative, its usage in this manner was mostly stopped.

Previous study has shown that ketamine causes sensory separation in the brain as a result of its ability to inhibit glutamate receptors in the brain. This results in elevated glutamate levels in the bloodstream, which causes sensations of disassociation. However, ketamine has the potential to cause unconsciousness, which is why it has been employed as an anesthetic. The researchers sought to learn more about the differences in the effects of ketamine and propofol on the brain, so they conducted a study in which they tested the two drugs on macaques.

The team’s research included administering ketamine and propofol to two adult macaques on separate dates and then observing their brain waves to see how they responded. For comparison purposes, they also acquired electrocorticographical recordings of macaques produced by other researchers working on previous research initiatives, which they used as a reference point.

When the researchers examined their data, they discovered that ketamine produced a dual state in the brain: one that was similar to normal awareness and the other that was similar to a type of anesthetic sleep. This resulted in a kind of liminal zone where elements of both states were present—one of them looked a lot like the condition a brain was in while under the influence of propofol, while the other looked a lot like the state a brain was in when sleeping and not under the effect of drugs. When they plotted the data on a graph, they discovered that it revealed approximately the same result: that the brain could live in both an unconscious and semi-conscious state at the same time. Apparently, it is the dual state nature of the brain that causes the sensations of disassociation, according to these researchers.

Categories: Clinical