A ‘Communication Breakdown’ During General Anesthesia

When ketamine is used for general anesthesia, two connected parts of the cortex turn to “isolated cognitive islands.”

3:39 PM

Author | Haley Otman

It's a topic that has long captivated doctors, scientists and the public — what exactly happens in your brain when you're oblivious on the operating table?

Some anesthesia drugs work in a straightforward manner by dampening down neurons in the brain. The mechanism of one anesthetic, however, has proved elusive: ketamine.

Certain doses of ketamine induce general anesthesia, though brain activity can still be robust, says Cynthia Chestek, Ph.D., co-senior author of a new study in NeuroImage.

Ketamine is used often in patient care and in laboratory settings. The new paper examines the neurological mechanisms at work during ketamine anesthesia.

Co-senior authors Chestek and anesthesiologist George Mashour, M.D., Ph.D., led the research team, which took precise measurements down to the level of neurons in animal models.

"We found that general anesthesia reflects a communication breakdown in the cortex, even though sensory information is getting processed," Mashour says. "But the processing appears to occur in isolated cognitive islands."

Turns out, two adjacent parts of the brain that work together in the waking state simply stop talking to each other under general anesthesia. When awake, communication between the primary somatosensory cortex and the primary motor cortex is critical to normal function.

"This supports the idea that what anesthesia does to cause unconsciousness is interrupt communication between brain areas, stopping the processing of higher-level information," says first author Karen Schroeder, a doctoral candidate in the U-M Department of Biomedical Engineering. "This was the first time anyone directly observed the interruption between the two areas using individual neurons."

Different fields collaborating

Chestek's biomedical engineering lab focuses on brain machine interfaces, recording activity of neurons and reading motor commands and sensory information in real time.

"This turned out to be really useful for the researchers in anesthesiology," Chestek says. So her team got on board to measure both areas of the brain, which kept firing during anesthesia.

"As soon as we injected ketamine, the sensory information disappeared from the motor cortex. Normally these areas are tightly connected."

The group plans to continue this work, turning next to investigate the level of anesthesia at which these changes in communication start to occur. They're also looking into what the groups of neurons are doing under anesthesia when they are still active but no longer communicating with each other.

"These insights could potentially improve our ability to monitor patients' level of consciousness," Schroeder says.

Funding for the work came from the National Institutes of Health.


More Articles About: Lab Report Anesthesiology and Anesthesia Surgery Pre- and Post-Operative
Health Lab word mark overlaying blue cells
Health Lab

Explore a variety of healthcare news & stories by visiting the Health Lab home page for more articles.

Media Contact Public Relations

Department of Communication at Michigan Medicine

[email protected]

734-764-2220

Stay Informed

Want top health & research news weekly? Sign up for Health Lab’s newsletters today!

Subscribe
Featured News & Stories gif of close up face in light purple colors waking up with wavy line behind it
Health Lab
Escape from Oblivion: How the Brain Reboots after Deep Anesthesia
How does the brain wake up after anesthesia? A new study illuminates our understanding of how our brains come back to consciousness after being put under.
In the OR
Health Lab
Rates of Pulmonary Complications Drastically Reduced with Newer Drug
New study shows significantly fewer post-surgery lung complications such as pneumonia and respiratory failure when sugammadex is used to reverse the effects of muscle relaxants used with anesthesia during surgery.
Health Lab
What Happens in the Brain During Unconsciousness?
Learn new research about the unconsciousness brain and how monitoring brain circuitry is assisting in better coma outcomes
Patient lies in hospital bed after surgery with bandage on head, displays toys later after recovery
Health Lab
Lifechanging results for young woman after orange-sized brain tumor removed
Young woman thrives after surgery to remove a pilocytic astrocytoma tumor in her brain.
Surgeon's tray with gloved hand reaching into wallet
Health Lab
Worries about costs, time off work and COVID-19 kept some older adults from having surgery
Elective surgery study shows older adults have concerns about what it will cost them, how much work they’ll miss and whether they’ll catch COVID-19.
AI algorithm alcohol medical symbols
Health Lab
For surgery patients, AI could help reduce alcohol-related risks
Surgery patients who drink at a risky level have higher risks of complications; surgical teams could use artificial intelligence to search their records for signs that they may need to cut back.