November 29, 2023

What is that bright light at the end of the tunnel?

Reports of near-death experiences — with tales of white light, visits from departed loved ones, hearing voices, seeing Heaven — capture our imagination.

The fact that these reports share so many common elements begs the question of whether there is something fundamentally real underpinning them — and that those who have managed to survive death are providing glimpses of a consciousness that does not completely disappear, even after the heart stops beating.

A new study, “Surge of neurophysiological coupling and connectivity of gamma oscillations in the dying human brain”, in the Proceedings of the National Academy of Science, provides early evidence of a surge of activity correlated with consciousness in the dying brain.

Researchers at the University of Michigan studied four patients who died after a cardiac arrest in the hospital while under EEG monitoring. All four were comatose and unresponsive and were ultimately removed from life support.

Upon removal of ventilator support, two of the patients showed an increase in heart rate along with a surge of gamma wave activity, considered the fastest brain activity and associated with consciousness.

Furthermore, the activity was detected in the so-called hot zone of neural correlates of consciousness in the brain, the junction between the temporal, parietal and occipital lobes in the back of the brain. This area has been correlated with dreaming, visual hallucinations in epilepsy, and altered states of consciousness in other brain studies.

Because of the small sample size, the authors caution against making any global statements about the implications of the findings. They also note that it’s impossible to know in this study what the patients experienced because they did not survive.

“We are unable to make correlations of the observed neural signatures of consciousness with a corresponding experience in the same patients in this study. However, the observed findings are definitely exciting and provide a new framework for our understanding of covert consciousness in the dying humans,” said one of the researchers.

Commenting on the study in MDEdge, Dr F. Perry Wilson of the Yale School of Medicine, described it as “the physiologic correlate of the near-death experience”:

It’s critical to realize two things here. First, these signals of consciousness were not present before life support was withdrawn. These comatose patients had minimal brain activity; there was no evidence that they were experiencing anything before the process of dying began. These brains are behaving fundamentally differently near death.

But second, we must realize that, although the brains of these individuals, in their last moments, appeared to be acting in a way that conscious brains act, we have no way of knowing if the patients were truly having a conscious experience. As I said, all the patients in the study died. Short of those metaphysics I alluded to earlier, we will have no way to ask them how they experienced their final moments.

Let’s be clear: This study doesn’t answer the question of what happens when we die. It says nothing about life after death or the existence or persistence of the soul. But what it does do is shed light on an incredibly difficult problem in neuroscience: the problem of consciousness.