The new research indicates that it works by interfering with a brain’s “dynamic stability”—a state where neurons can respond to input, but the brain is able to keep them from getting too excited.

To find out how propofol achieves that disruption, the MIT team looked at electrical recordings from parts of the brain tied to vision, sound processing, spatial awareness, and executive function in animals that had been dosed with the drug. They then compared those measurements to some that were taken before propofol was administered.

They found that the conscious animal brains showed increased neural activity after input like a sound or a new sight and then returned to a baseline level. But under the effects of propofol, the brain did some odd things. Previous research has shown that animals given the drug lose consciousness but maintain cognition and brain activity—basically, your brain can still process things like sound and smell, even if you’re not aware of it. The team, which published their findings on Monday in the journal Neuron*, *found that this effect may be due to the brain taking longer to return to its baseline after a sensory input while on the anesthetic, sending brain activity “into chaos,” as one neuroscientist put it.