Propofol study shows how consciousness research could improve anesthesia safety

Editor's Note

Propofol research published in the journal Neuron has broader implications for enabling more precise, safer doses of anesthesia, according to an August 14 report in Anesthesiology News.

According to the article, anesthesiologists tend to use higher doses of anesthetics because they rely on indirect measures, such as heart rate and breathing, rather than directly monitoring brain activity. However, senior study author Earl K. Miller, PhD, Picower Professor of Neuroscience at MIT, argues that measuring brain activity more accurately could improve precision in achieving the desired level of sedation.

The study explored how propofol induces unconsciousness by disrupting the brain's dynamic stability—the ability of the brain to maintain a balance between controlled stability and excitability. This balance is crucial for consciousness, and its disruption leads to unconsciousness, Anesthesiology News reports. Previous studies had conflicting results on whether too much stability or overexcitability causes the loss of consciousness, largely due to the challenges of measuring stability in such a complex system as the brain.

To address these challenges, Miller and his colleagues developed a novel mathematical tool called delayed linear analysis for stability estimation (DeLASE). By recording the electrical activity in the brains of macaques during transitions from consciousness to propofol-induced unconsciousness and back, the researchers observed that the brain's ability to quickly return to its "true path" after disturbances was impaired under anesthesia. As propofol was administered, the brain's activity became increasingly unstable, suggesting that the drug's inhibition of neuron activity escalates this instability, leading to unconsciousness. 

According to the article, researchers hope to identify common mechanisms across various anesthetics, which could point to dynamic stability as the key factor determining consciousness. This understanding could lead to safer sedation practices and contribute to a broader understanding of consciousness itself.