In 1961, after falling ill with pneumonia, Hollywood star Elizabeth Taylor had a near-death experience.

She told The Oprah Winfrey Show in 1992 that she had undergone surgery and was clinically dead for five minutes.

After coming to, the actress claimed she had an out-of-body experience, during which she saw her late husband, Mike Todd, who told her, “It’s not your time… you have to fight to go back.”

And she did. Her time eventually did come in 2011.

On the other hand, Australian media mogul Kerry Packer had a close encounter after falling from his polo horse in 1990. Clinically dead for seven minutes, he was brought back to life.

Talking about the experience, he famously said there were no bright lights or tunnels of light. He simply said, “There’s nothing there."

Modern medicine is bringing more people back from clinical death and many of them talk of strange, often very pleasant, experiences while they’re on the “other side”.

The patients’ reports reveal a pattern of several recurring elements:

• Out-of-body experience.

• Accurate visual and auditory perception while out of the body.
  

• Feelings of peace and painlessness.

• Light phenomena (encounters with loving white light).

Reports of near-death experiences capture the public imagination and the attention of empirical scientists.

The fact that these reports share so many common elements raises the question: Is something fundamentally real underpinning them?

Are those who have managed to survive death providing glimpses of a consciousness that does not completely disappear, even after the heart stops beating?

A study published in the Proceedings of the National Academy of Science, provides early evidence of a surge of activity correlated with consciousness in the dying brain.

The study, led by Dr Jimo Borjigin, associate professor in the Department of Molecular and Integrative Physiology and the Department of Neurology, and her team is a follow-up to animal studies conducted almost 10 years ago in collaboration with Dr George Mashour, the founding director of the Michigan Center for Consciousness Science.

Similar signatures of gamma activation were recorded in the dying brains of both animals and humans upon a loss of oxygen following cardiac arrest.

“How vivid experience can emerge from a dysfunctional brain during the process of dying is a neuroscientific paradox,” Dr Mashour said. “Dr Borjigin has led an important study that helps shed light on the underlying neurophysiologic mechanisms.”

The team identified four patients who died due to cardiac arrest and ultimately had their life support removed.

However, at that stage, 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.

The activity was detected in the so-called hot zone of neural correlates of consciousness at the back of the brain – an area linked in other brain studies to dreaming, visual hallucinations in epilepsy, and altered states of consciousness.

These two patients had had brain seizures during their lives. The other two patients did not display the same increase in heartrate upon removal from life support, nor did they have increased gamma activity.