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Major discovery: Brain activity exists beyond flat line

Teresa Tanoos's picture
Brain activity found during deepest comas

Researchers have made a major discovery that shows evidence of brain activity beyond a flat line EEG, therefore disputing other research that suggests no brain activity or possibility of life exists after a person enters into a flat line stage.

This startling discovery suggests there is a "whole new frontier in animal and human brain functioning," according to researchers from the University of Montreal whose study was published in the journal PLOS ONE.

For the study, the research team observed a human patient who was in an "extreme deep hypoxic coma" and also on strong anti-epileptic medication required for health issues.

While observing the patient, the team said they saw unexplainable phenomena, as the patient was showing cerebral activity in the brain.

Accordingly, the researchers decided to experiment on cats in an effort to recreate the patient's state while in a coma. In order to do so, they put the cats into a very deep, but reversible coma with an anesthetic named isoflurane.

After being put to sleep, the cats passed the flat EEG line, which is the stage connected to silence in the cortex of the brain.

Once the cats entered this flat line stage, the research team observed 100% cerebral brain activity through oscillations that were generated in the hippocampus and then transmitted to the cortex. The hippocampus is an area of the brain responsible for memory and learning.

As a result, the research team concluded that the EEG waves they observed in the brains of the cats were the same as those they observed in the brain of the human patient.

According to lead study author, Daniel Kroeger, this finding shows evidence that the brain is able to survive in an extremely deep coma if the integrity of the nervous structures is preserved.

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"We also found that the hippocampus can send 'orders' to the brain's commander in chief, the cortex,” added Kroeger, who is with the Department of Stomatology at the University of Montreal.

“The possibility of studying the learning and memory processes of the hippocampus during a state of coma will help further understanding of them. In short, all sorts of avenues for basic research are now open to us," he said.

According to the director of the study, Dr. Florin Amzica, the potential for neuroprotection from the extreme deep coma is the most helpful aspect of the study.

When some patients suffer a major injury, their physicians typically put them into an induced coma in an effort to protect them and their brain while they recover. But Amzica believes that the extreme deep coma used in the study could be more protective.

"Indeed, an organ or muscle that remains inactive for a long time eventually atrophies. It is plausible that the same applies to a brain kept for an extended period in a state corresponding to a flat EEG," said Amzica, a professor of the School of Dentistry at the University of Montreal.

"An inactive brain coming out of a prolonged coma may be in worse shape than a brain that has had minimal activity, he added.

But Amzica also warns that it’s important for patients and their loved ones to understand exactly what these findings mean.

"Those who have decided to or have to 'unplug' a near-brain-dead relative needn't worry or doubt their doctor. The current criteria for diagnosing brain death are extremely stringent,” he said.

“Our finding may perhaps in the long term lead to a redefinition of the criteria, but we are far from that. Moreover, this is not the most important or useful aspect of our study."

SOURCE: Human Brain Activity Patterns beyond the Isoelectric Line of Extreme Deep Coma, doi:10.1371/journal.pone.0075257, published in PLOS ONE, 18 September 2013