Has science just found the cause of near-death experiences?

Many science-related websites and news organisations are now reporting on a new study that found an increase in EEG gamma waves at the time of death.

The authors of the study analysed the electroencephalograms (EEG) of four dying patients and found that the resulting hypoxic (lack of oxygen) state stimulated a spike in gamma wave activity and increased brain connectivity in two of them demonstrating that the brain remains active at the time of death.

Title: Surge of neurophysiological coupling and Connectivity of gamma oscillations in the dying human brain
Author(s): Gang Xu, Temenuzhka Mihaylova et al.
Journal: PNAS
Date of publication: 1st May 2023
Link to full paper.

Most of them suggest that this study explains near-death experiences simply as a last gasp dream-gasm generated by a hypoxic, dying brain.

Some people may experience something like near-death experiences in these moments, Kondziella said, but we may never know for sure. And again, these experiences may not be unique to death — a more likely explanation for near-death experiences that encompasses both life-threatening experiences and non-life-threatening experiences, he said, may be “REM sleep intrusion into wakefulness,” a situation in which the brain blends waking and dreaming states. (REM sleep is marked by dreaming and brain activity patterns that are very similar to waking, including gamma waves and other, lower-frequency waves.)

— Stephanie Pappas, Scientific American

This may well be the case, but we must also remember that correlation does not equal causation.

The materialist view would be that this activity demonstrates the brain potentially generating experiences at the time of death.
But for those who argue that consciousness is non-local, this EEG activity could simply be a reflection of what consciousness is experiencing.

Just as the tracing on the screen of the EEG machine does not cause electrical activity in the brain, that electrical activity does not cause the experience of phenomenal consciousness.

Some points to also hold in mind…

  • Both of the patients who demonstrated increased gamma activity had a history of seizures. One of them developed status epilepticus a day prior to her death (although the authors note that careful inspection of the EEG data found no evidence of seizure activity in the final hours of the patients lives).
  • We do not know if this EEG activity was accompanied by any actual experiences, a point noted by the authors:

Although the marked activation of the posterior hot zone in the dying brain is suggestive of elevated conscious processing in these patients, it does not demonstrate it. Unlike the earlier study in healthy human subjects where the TPO junction activation was correlated with self-reported dream contents, we cannot determine whether the activation of the posterior hot zone detected in our patients was correlated with having a subjective experience, as none survived the cardiac arrest. As such, it remains possible that this neurophysiological surge is epiphenomenal or pathological.

Gang Xu et al.
  • The increased gamma activity and increased interconnected cerebral activity could be linked directly to generating near-death experiences. But even so, they do not sufficiently explain the content of those experiences such as veridical reporting of events occurring in the room, meeting (only) deceased people, and a structured organised and often meaningful series of experiences that is often reported as being more real than real, rather than chaotic, random, nonsensical events as often seen in dream states.

Previous studies on increased gamma activity at the time of death have been critiqued here: Electrical activity in the brain at the time of death.

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