An ambitious effort to create a neurophysiological paradigm to explain near-death experiences has failed to capture many fascinating and often perplexing aspects of people’s brushes with death, top University of Virginia experts argue.
UVA near-death researchers Bruce Greyson, MD, and Marieta Pehlivanova, PhD, laud the international team of scientists who developed the model, called Neurophysiological Evolutionary Psychological Theory Understanding Near-Death Experience, or NEPTUNE. The NEPTUNE team aimed to bring scientific rigor to understanding near-death experiences (NDEs) – a goal shared by Greyson and Pehlivanova. But the UVA experts say the model, for all its sophistication, leaves far too many unanswered questions to be considered a satisfactory solution to the mysteries of NDEs.
“The NEPTUNE model was a pioneering attempt to explain NDEs, but it selectively ignored scientific evidence that contradicts the model and failed to address some of the most important and defining parts of NDEs,” said Greyson, part of the Division of Perceptual Studies at UVA’s School of Medicine.
Understanding Near-Death Experiences
In their new paper, Greyson and Pehlivanova outline many facets of NDEs that the NEPTUNE model – and neurophysiology more broadly – still cannot explain. For example, the NEPTUNE researchers argue that near-death “hallucinations” could be caused by changes in blood brain gases, endorphins or other chemical or electrical activity in the brain.
But Pehlivanova and Greyson note that neurological hallucinations typically only involve a single sense, such as hearing or sight. Those types of single-sense hallucinations do not align, the UVA researchers say, with the robust and often life-changing encounters near-death experiencers report having with loved ones or even with people they have never met. Experiencers can often recall what they saw, heard, smelled and touched while dead, and the encounters are often burned into their brains for decades – unlike hallucinations, which are quickly forgotten.
The NEPTUNE group also advanced a potential explanation for the out-of-body experiences near-death experiencers sometimes report. In these instances, experiencers feel disconnected from their physical forms and sometimes recall looking down on their own bodies. The NEPTUNE scientists pointed to two studies suggesting that this may be the result of the activation of a particular region in the brain, the temporoparietal junction (TPJ). But Greyson and Pehlivanova counter that the experiences reported in those two studies are “quite unlike” the out-of-body experiences described in NDEs. During TPJ activation, there is a sense of disembodiment, but visual perception remains normal – experiencers don’t see their own forms or feel like they can move about independent of their bodies as near-death experiencers do.
Further, the UVA researchers note that electrical stimulation studies have already tested the TPJ theory. Stimulating the brain region produced visual hallucinations, but study participants did not believe they had left their bodies, Greyson and Pehlivanova write: “There is no evidence that electrical brain stimulation has ever produced accurate perception of anything not visible to the physical eyes, or that persists when eyes are closed, or that is from an out-of-body perspective – all features observed in spontaneous OBEs.”
Seeking Answers About NDEs
While Pehlivanova and Greyson raise several additional concerns about the NEPTUNE model, they were eager to applaud its developers for their efforts. “Martial et al have done a monumental job summarizing the major arguments in this field, relying on both theoretical and empirical contributions from the NDE literature and broader major research,” they write. But they say a lack of empirical data and other flaws in the NEPTUNE model raise concerns that “temper our enthusiasm for the model and our confidence that it can provide a comprehensive explanation for NDEs.”
In other words, neurophysiology still can’t explain near-death experiences, Pehlivanova and Greyson say. But they are eager for the conversation to continue.
“NDEs are typically triggered by physiological events, so it makes sense to explore those connections and look for cause-and-effect. But this effort is just at the beginning stage, and it is important to keep being open-minded as we continue the search,” Greyson said. “Understanding NDEs can unlock the door to larger questions about consciousness and the brain. We hope the quest to appreciate all aspects of NDEs will lead us not just to mapping the triggers of NDEs but also to their meaning and to a better understanding of the boundary between life and death.”
Paper Published
Greyson and Pehlivanova have published their response in the scientific journal Psychology of Consciousness: Theory, Research and Practice. The article is open access, meaning it is free to read.
About the Division of Perceptual Studies (DOPS)
Established in 1967 under the leadership of UVA psychiatrist Ian Stevenson, MD, DOPS stands as the most productive university-based research group in the world dedicated to exploring phenomena that challenge conventional scientific paradigms concerning human consciousness. At the core of DOPS’ research mission lies the commitment to rigorous evaluation of empirical evidence surrounding exceptional human experiences and capacities, including utilization of a state-of-the-art neuroimaging lab. DOPS extends its focus beyond fundamental empirical research and explores the profound implications of such research for scientific theory and society at large. By actively sharing insights and findings, DOPS strives to contribute meaningfully to the understanding of consciousness, bridging the gap between scientific inquiry and public awareness.
To keep up with the latest medical research news from UVA, bookmark the Making of Medicine blog at https://makingofmedicine.virginia.edu.
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