A groundbreaking UK study reveals that high doses of ketamine can cause a complete, temporary shutdown of brain activity—observed for the first time in sheep.
First synthesized in 1962, ketamine is a psychotropic drug primarily used as a general anesthetic. Yet, it's also notorious as a recreational drug with profound effects. Despite over 50 years of research, ketamine continues to surprise scientists. In a study published in Scientific Reports on June 11, 2020, researchers from the University of Cambridge shared a remarkable observation.
While examining brain activity patterns in six sheep with Huntington's disease, the team administered ketamine and noted a complete halt in brain activity lasting several minutes in five of the animals. This wasn't merely reduced activity—it was a full stop, followed by normal resumption, as confirmed by electroencephalographic (EEG) readings.
Lead researcher Jenny Morton described it vividly: "It was like turning them off and on again."
The study tested ketamine doses from 3 mg/kg to 24 mg/kg—spanning the upper limit for anesthesia and the lower threshold for recreational use. Results revealed a distinct three-stage cycle in sheep brain activity: initial sedation, followed by dissociative anesthesia with no voluntary movement, and finally a fully conscious yet immobile alert state.
Total shutdown occurred only at the highest doses, but the sheep continued breathing normally. Certain cortical areas remained active, confirming the brain was still alive and undamaged.
These insights, drawn from rigorous EEG monitoring and controlled dosing, could deepen our understanding of ketamine's anesthetic mechanisms and pave the way for treatments targeting neurological and psychiatric disorders.
