Researchers investigating the effect of therapeutic drugs on people with Huntington’s made an unusual discovery about how ketamine affects the brain. They administered what would be considered a high recreational dose to sheep and found that the drug appeared to “switch off” the brain, which could explain why some ketamine abusers ‘K-hole’ – a state of oblivion likened to a near-death experience – followed by serenity. The study was published in the journal Scientific Reports.
The researchers were using electroencephalography (EEG) to measure changes in the brain waves of sheep after they administered ketamine, an anesthetic and pain relief drug, when they made the discovery. While the sheep were unconscious their brain activity was sustained at a low level, but as it started to wear off it began spiking between high and low frequency. The bursts began as irregular oscillations but within a few minutes were occurring at a regular rate.
“As the sheep came round from the ketamine, their brain activity was really unusual,” said Professor Jenny Morton, lead researcher on the study from the University of Cambridge’s Department of Physiology, Development and Neuroscience, in a statement. “The timing of the unusual patterns of sheep brain activity corresponded to the time when human users report feeling their brain has disconnected from their body.”
Things got stranger as six of the sheep were given a single higher dose of ketamine, which would be considered at the high end of the anesthetic range. At first, they showed the same oscillating brain wave response but after two minutes the researchers were shocked to see that the brain activity of five of these six sheep stopped completely. For one of the animals, this lasted for several minutes, a phenomenon that has never been seen before.
“This wasn’t just reduced brain activity. After the high dose of ketamine, the brains of these sheep completely stopped. We’ve never seen that before,” said Morton. “A few minutes later their brains were functioning normally again – it was as though they had just been switched off and on.”
The researchers believe this break in brain activity might be responsible for what ketamine abusers describe as the “k-hole”. The dosages used recreationally are several times higher than that which was given to the sheep, which the researchers state has the capacity to cause liver damage and even stop the heart.
Ketamine is used medically as a ‘dissociative anesthetic’, which means patients appear to be awake since they are moving and making sounds, but they aren’t actually processing the information or feeling pain. Many describe the experience as feeling as though their mind has separated from their body.
“Our purpose wasn’t really to look at the effects of ketamine, but to use it as a tool to probe the brain activity in sheep with and without the Huntington’s disease gene,” said Morton. “But our surprising findings could help explain how ketamine works. If it disrupts the networks between different regions of the brain, this could make it a useful tool to study how brain networks function – both in the healthy brain and in neurological diseases like Huntington’s disease and schizophrenia.”