Can a new study lay the basis for the scientific understanding of mystical-sounding near-death recollections, filled with vivid light and vibrant meetings with deceased loved ones?

When researchers recorded and analyzed electroencephalograms (EEGs) of the brain activity of rats during cardiac arrest, they discovered that in the seconds after the heart stopped beating, there was a final burst of brain activity characteristic of conscious perception.

The finding indicates that the source of the electrical activity in the immediate aftermath of clinical death was the brain itself, not an outside or supernatural source.

National Geographic spoke with lead study author Jimo Borjigin, Ph.D., associate professor of physiology and neurology at the University of Michigan Medical School.

What questions were you trying to answer with your study?

We were testing the assumption: At the moment of cardiac arrest, is the brain really dead? At the moment the heart stops, does the brain go silent right away? The assumption is that the brain has no activity at the point after the heart stops—and therefore any vivid visual experiences, such as bright lights or seeing deceased relatives, has to be supernatural in origin or something we just don't understand.

And what did you find?

Our study found the opposite of that assumption: that even after the heart stops, the brain not only still functions but is hyperactive, exceeding levels found during the conscious waking state. The final burst of brain activity lasted about 30 seconds.

What makes this finding significant?

This is the first experiment to show that there may be some scientific, rational reasons to explain what's going on during that critical moment when the heart stops. The ground for the supernatural interpretation of the experience is no longer solid. It is shaken because our study shows that the brain at that moment has elevated activity.

How do study findings and observations in the brains of rats relate to what happens in human brains and human beings?

In people's descriptions of life-after-death experiences, there are light perceptions associated with visual function. If you were to say those experiences came from their brains, their visual cortex had to be activated. So with rats, we'd have to look at their visual cortex as well, which is what we did. Our data shows the visual cortex is highly activated in rats after the heart stops. There are no data about this for humans, but we would now know what to look for in humans because of this study.

People's near- and after-death experiences also often include meetings with dead relatives. Does this study tell us anything about that?

We don't have any data for that. Perhaps a memory is triggered at the moment of crisis. But that's speculation.

Is there a reason for that last burst of brain activity?

In general, the brain is very plastic in recovering and finding solutions to injury or crisis. For example, for the brain to recover from sleep loss, you just have to sleep more later on. The heart stopping is the severest crisis the brain will ever see. I have a hypothesis—there is no proof of this—that perhaps this [final burst of increased brain activity] is a built-in defense against this kind of crisis. I hypothesize the evolutionary reason for that increased activity in the brain is simply the brain trying to rescue itself. It's the last-ditch effort.

Why do you think this study is generating so much interest?

Until now there hasn't been a scientific explanation for these experiences, and survivors are looking for explanations. In fact, I think the incidence of having these experiences is even more frequent than reported.

Why would that be?

I think they don't want to be thought about as being weird. Many scientists are dismissive. They may feel they have nowhere to turn. This study provides an alternative explanation.

Will this study convince people, one way or the other, about the existence of life after death?

It's very hard to change people's minds, to convince people about life after death or not.

Are you planning further experiments to follow up?