What happens after death? Scientists discover ‘surge of activity’ in the dying brain

ANN ARBOR, Mich. — Researchers have discovered evidence suggesting that a surge of activity associated with consciousness occurs in the dying brain. This activity appears to take place in a region of the brain linked to dreaming, visual hallucinations due to epilepsy, and altered states of consciousness.

This discovery may help explain accounts from individuals who have had near-death experiences, including seeing white lights, reuniting with deceased loved ones, and hearing voices. Researchers from the University of Michigan studied four patients who died from cardiac arrest while under electroencephalogram (EEG) monitoring, a test that measures electrical activity in the brain.

All four patients were comatose and unresponsive, with doctors saying they were beyond medical help, and ultimately removed from life support with their families’ consent. As medical professionals removed the ventilator, two of the patients exhibited an increase in heart rate and a surge of gamma wave activity, which is the fastest brain activity associated with consciousness. These two patients had a history of seizures, but none occurred in the hour preceding their deaths. The other two patients did not display similar increases in heart rate or brain activity.

Woman with sick, dying husband
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This study builds on an animal study conducted nearly a decade earlier, which found similar gamma activation signatures in the dying brains of both animals and humans following oxygen loss due to cardiac arrest. However, the researchers caution against making broad conclusions based on their findings, as the sample size was small, and it is impossible to know the patients’ experiences since they did not survive.

“How vivid experience can emerge from a dysfunctional brain during the process of dying is a neuroscientific paradox. Dr. Borjigin has led an important study that helps shed light on the underlying neurophysiological mechanisms,” says Dr. George Mashour, a study co-author and founding director of the Michigan Center for Consciousness Science, in a media release.

“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 dying humans,” explains Nusha Mihaylova, M.D., Ph.D., a clinical associate professor in the Department of Neurology.

Larger studies may offer crucial data to determine whether these bursts of gamma activity are evidence of hidden consciousness even near death.

The findings are published in the journal Proceedings of the National Academy of Sciences.

Near-death experiences may not be hallucinations

Despite the new report linking this brain activity to the region of the mind which experiences visual hallucinations, a 2022 study exploring what people go through when they’re close to death came to one important conclusion — “near-death experiences” are a real thing, even if we can’t explain them.

Researchers from NYU Grossman School of Medicine said something else is actually happening. Their main finding was that these events don’t have much in common with the experiences someone has if they’re hallucinating or using a psychedelic drug. Instead, people who have a near-death experience typically report five different events taking place:

  • A separation from their body with a heightened, vast sense of consciousness and recognition that they’re dying.
  • They “travel” to a different location.
  • A meaningful and purposeful review of their life, involving a critical analysis of all their past actions — basically, their life flashes before their eyes.
  • Going to a place that feels like “home.”
  • Returning back to life.

The 2022 study also found the presence of gamma activity and electrical spikes when people are technically dying. This is typically a sign of a heightened state of consciousness when scientists measure it using an electroencephalography (EEG). The findings further back up the claims from people who say they “left their body” while dying.

“What has enabled the scientific study of death is that brain cells do not become irreversibly damaged within minutes of oxygen deprivation when the heart stops. Instead, they ‘die’ over hours of time. This is allowing scientists to objectively study the physiological and mental events that occur in relation to death,” says lead author Sam Parnia in a media release.

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South West News Service writer Alice Clifford contributed to this report.

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