Brain Connectivity May not Rebound.

• Position: MEDICALLY INDUCED COMA

Prolonged anesthesia, also known as medically induced coma, is a life-saving procedure carried out across the globe on millions of patients in intensive medical care units every year. However, following prolonged anesthesia--which takes the brain to a state of deep unconsciousness beyond short-term anesthesia for surgical procedures--it is common for family members to report that after hospital discharge their loved ones were not quite the same.

"It is long known that ICU survivors suffer lasting cognitive impairment, such as confusion and memory loss, that can languish for months and, in some cases, years," says Michael Wenzel, a former postdoctoral researcher at Columbia University, who indicates that reports of post-hospital cognitive dysfunction likely will become even more prevalent because of the significant number of coronavirus patients dependent on ventilators who have taken days or weeks to awake from medically induced comas.

Until now, despite the body of evidence that supports the association between prolonged anesthesia and cognition, the direct effects on neural connections have not been studied, says senior author Rafael Yuste, professor of biological sciences. "This is because it is difficult to examine the brains of patients at a resolution high enough to monitor connections between individual neurons."

Inspired by Wenzel's experience in neuro-intensive care in Germany, the researchers established a miniature ICU-like platform for mice. They performed continuous anesthesia for up to 40 hours, many times longer than the longest animal study to date (only six hours).

The researchers performed in vivo two-photon microscopy, a type of neuro-imaging that Yuste...