If you’ve ever had a medical procedure requiring general anesthesia, you know that it’s a hallucinatory experience. One moment you’re wide awake, and the next you’re blacked out, in a daze with no idea what’s happened. Putting a patient under anesthesia A long history It dates back more than 200 years, but how medicine works Mystery.
A team of neuroscientists at MIT may have found the answer in the case of propofol, which has been widely used since the 1980s to make patients unconscious and keep them there. New research suggests that propofol works by disrupting the brain’s “dynamic stability” — the state in which neurons can respond to input but the brain can keep them from becoming excited.
To understand how propofol causes this disruption, the MIT team looked at electrical recordings from parts of the brain associated with vision, speech processing, spatial thinking, and executive function in animals given the drug, and compared those measurements with those taken before propofol was administered.
The team found that the brains of conscious animals experience increased neural activity after inputs such as sounds or new sights, then return to baseline levels. But under the influence of propofol, the brain behaves strangely. Previous studies have shown that animals given the drug lose consciousness but maintain cognition and brain activity, meaning the brain can still process things like sounds and smells, even if they’re not conscious. The team, who published their findings on Monday, said: Neuron, It turns out that this effect may be because the brain takes time to return to baseline after receiving sensory input while under anesthesia, causing brain activity to go into a state of “confusion,” in the words of one neuroscientist.
When the researchers tried to replicate the experiment in a digital model of the brain’s neural networks, they found that they could replicate propofol’s destabilizing effects by tweaking specific nodes in the virtual brain.
“We looked at a simple circuit model of interconnected neurons, and in it, when we increased inhibition we saw destabilization, suggesting that increased inhibition could create instability that could lead to loss of consciousness,” said Adam Eisen, a graduate student at MIT and co-author of the study. press release.
“The brain has to function on the edge of excitability and chaos: neurons need enough excitability to influence each other, but too much and they fall into chaos,” study author and MIT professor Earl K. Miller said in a release. “Propofol appears to disrupt the mechanisms that keep the brain in its narrow operating range.”
It is not known whether other anesthetics work in the same way as propofol, but the team plans to explore this in future studies, potentially allowing doctors to be more precise when anesthetizing patients.
