First Recording of Dying Brain Shows Memory Patterns

For the first time, neuroscientists have recorded the brain activity of a dying person, revealing a brain wave pattern similar to that seen when memories are recalled.

Although only a single case study, researchers say the recording raises the possibility that as we die, our lives really do flash before our eyes.

Dr Ajmal Zemmar

“The same neurophysiological activity patterns that occur in our brains when we dream, remember, meditate, concentrate — these same patterns also appear just before we die,” study investigator Ajmal Zemmar, MD, PhD, assistant professor of neurosurgery at the University of Louisville, Louisville, Kentucky, told Medscape Medical News.

The research was published online February 22 in the Frontiers in Aging Neuroscience.

Accidental Finding

The recording of brain activity was captured inadvertently in 2016 when neuroscientists used continuous EEG to detect and treat seizures in an 87-year-old man who had developed epilepsy after a traumatic brain injury. While undergoing the EEG, the patient had a cardiac arrest and died.

In the 30 seconds before and after blood flow to the brain stopped, the EEG showed an increase in gamma oscillations. These are brain waves known to be involved in high cognitive functions, including conscious perception and memory flashbacks.

Researchers also noted changes in alpha, theta, delta, and beta wave activity just before and just after cardiac arrest, and that changes in one type modulated changes in others. That suggests a coordinated rhythm, which further suggests the activity is more than just the firing of neurons as they die.

“When you observe this and you observe the rhythmic oscillation, you are inclined to think this may be a coordinated activity pattern of the brain rather than a mere discharge when the brain dies,” Zemmar said.

Although they’ve had the data since 2016, the researchers held off on publishing in the hopes of finding similar recordings in other individuals. That their 5-year search yielded no results illustrates just how difficult a study like this is to conduct, Zemmar noted.

“We’re trying to figure out how to do this in a predictable way, but obtaining datasets like this is going to be challenging,” he said.

Although Zemmar was unable to find recordings of activity in the dying brains of other humans, he did find a similar study conducted with rats in 2013.

In that research, investigators reported a surge of brain activity in rats just prior to and immediately after experimental cardiac arrest. Changes in high- and low-frequency brain waves mirrored those documented in the current case study.

Bringing a Picture Together

Commenting on the new study for Medscape Medical News, George Mashour, MD, PhD, professor and chair of anesthesiology and professor of neurosurgery and pharmacology at the University of Michigan, Ann Arbor, said the results are eerily similar to a 2013 study that he co-authored.

Although the current research is just a single case study, Mashour said when taken with his team’s findings in rats and other work, the new findings are “starting to put a picture together of what might be going on in the dying brain.”

“They were able to record throughout the process of cardiac arrest and death and what they found was strikingly similar to what we found in our highly controlled animal study,” said Mashour, who is also the founding director of the Center for Consciousness Science at the University of Michigan.

“There was a surge of higher-frequency activity and there was coherence across different parts of the brain,” he added. “That suggests that what we found in the rigorous controlled setting of a laboratory actually translates to humans who are undergoing the clinical process of dying.”

What remains unclear is whether this brain activity explains the near-death experiences described in the literature, which include “life recall” of memories, Mashour said.

“This higher frequency surge that’s happening around the time of death, is that correlated with experiencing something like this near-death experience? Or is it just a neural feature that can just as easily happen in an unconscious brain?” he asked.

The study was funded by the Heidi Demetriades Foundation, the ETH Zürich Foundation, and the Henan Provincial People’s Hospital Outstanding Talents Founding Grant Project. Zemmar and Mashour have disclosed no relevant financial relationships.

Front Aging Neurosci. Published online February 22, 2022. Full text

For more Medscape Neurology news, join us on Facebook and Twitter

Source: Read Full Article