Statistical model defines the effect of ketamine anesthesia on the brain

A team of researchers at the Picower Institute for Learning and Memory at the Massachusetts Institute of Technology (MIT) Picower Institute for Learning and Memory and Massachusetts General Hospital developed the first precise description of how ketamine anesthesia affects The statistical model of the brain has laid a new foundation for three research advances: understanding how ketamine induces anesthesia; monitoring the unconscious state of surgical patients; and applying a new method of analyzing brain activity

The new model published in the journal PLOS Computational Biology is based on the measurement of the brain rhythms of 9 humans and 2 animals, and defines the unique and characteristic state of brain activity during ketamine-induced anesthesia.

Senior author Emery N.

Brown is a professor at MIT's Department of Brain and Cognitive Sciences, the Institute of Medical Engineering and Science, and Harvard Medical School.

Make a model

After MGH's colleagues showed the alternating patterns of high-frequency gamma rhythm and extremely low-frequency delta rhythm in patients under ketamine anesthesia, Brown's team, led by graduate student Indie Garwood and postdoctoral fellow Sourish Chakravarty, began a rigorous analysis

For the analysis, Garwood and the team collected data from two main sources

Using Hidden Markov Model to analyze the readings, using the beta distribution as the observation model, not only captures and characterizes the previously observed alternation between gamma and delta rhythms, but also captures some other more subtle mixing of the two rhythms Status

Importantly, the model shows that the various states move sequentially through a feature and defines the duration of each state

Brown added that describing patterns of brain states and their transitions will also help neuroscientists better understand the role of ketamine in the brain

Garwood said: "The lack of this model prevents our other work from advancing in a rigorous way

new idea

Brown said that as neuroscientists learn more about how ketamine induces unconsciousness from these efforts, an important revelation has become apparent

"In a sense, I can make your brain overactive and make you unconscious, or I can slow your brain and make you unconscious," he said

In addition to considering this hypothesis, the team is also working on several new projects, including measuring the effects of ketamine in wider brain regions and measuring the effects of subjects waking up from anesthesia

The author added that the development of a system that can monitor coma under ketamine anesthesia in a clinical setting requires the development of a model version that can run in real time

DOI 10.
1371 / journal.
pcbi.
1009280

Article title

A hidden Markov model reliably characterizes ketamine-induced spectral dynamics in macaque local field potentials and human electroencephalograms