Did medical equipment capture a near-death experience (NDE) in the brains of two very different coma patients after they were removed from life support? That’s the question at the center of a new study, which may have evidence of two women encountering a bright light or having a similar experience.

The first of the patients, aged 24, suffered a heart attack at home and underwent three defibrillations at the hospital – Michigan Medicine, the hospital of the University of Michigan – plus a pacemaker surgery. After she fell into a deep coma and her doctors deemed her to be beyond medical help, her family agreed to remove life support.

The other patient, aged 77, suffered symptoms of a stroke at home (nausea and a drooping face) and underwent brain surgery at the same hospital to treat a hematoma. In a situation similar to that of the first woman, her family gave consent to end her life.

What Happens to Your Brain When You Die?

In both cases, the women died with electroencephalogram sensors attached to their scalps, to record brain waves and brain activity. The machines ultimately recorded much more than the minimal activity dictated by conventional wisdom.

Gamma waves surged in the brain and passed through an important “hot zone” on the back of the brain, the junction of the temporal, parietal and occipital lobes.

Read More: What’s Happening in Your Brain Moments Before Death?

Near Death Experiencers

The temporo-parieto-occipital junction is believed to play a role in several modes of consciousness, including waking, dreaming and psychedelic states. Could it also light up during so-called NDEs, which can be intensely spiritual in nature?

Medical emergencies are more than capable of inducing NDEs. Some 10 to 20 percent of human heart attack survivors report having had NDEs that are highly lucid or “realer than real,” the study says.

NDE experiencers have also reported out-of-body experiences and encounters with bright lights and dark tunnels, according to the University of Virginia Division of Perceptual Experiences. Some have reviewed past life experiences (their lives “flashed before their eyes”) or previewed those to come.

Read More: Can Science Explain Near Death Experiences?

Can Brain Scans Detect Near Death Experiences?

In the study, the women couldn’t tell the researchers what they’d experienced before dying. And gleaning those experiences from sensor readings, the so-called neural correlates of consciousness, brings up a host of philosophical issues and an extensive ongoing debate.

Nusha Mihaylova, a clinical professor at the University of Michigan, acknowledges these limitations in a press release and adds, “However, the observed findings are definitely exciting and provide a new framework for our understanding of covert consciousness in the dying humans.”

The study also reviewed data from two other patients, male and female heart attack patients who fell into a coma and died in the same manner as the two women. Their brains showed no surge in gamma waves, possibly due to weakened autonomic nervous systems, the paper says.

A related study from 2015 found that when researchers suffocated rats with carbon dioxide, it caused a “brainstorm” triggered by the autonomic nervous system. The hypoxia caused a heart attack, the paper says, which prompted the autonomic nervous system to stimulate the brain powerfully.

Read More: Psychedelic Drugs and Near-Death Experiences Decrease Fears of Dying