New Scientific Model Still Falls Short of Explaining Near-Death Experiences, Researchers Say
An ambitious scientific attempt to explain near-death experiences (NDEs) using brain physiology and evolutionary psychology is drawing serious criticism from leading researchers who say the model leaves many of the most important questions unanswered. According to experts from the University of Virginia (UVA), the proposed framework may be sophisticated, but it still cannot fully explain what people actually report when they come close to death.
The debate centers on a recently proposed theory called NEPTUNE, short for Neurophysiological Evolutionary Psychological Theory Understanding Near-Death Experience. The model was developed by an international team of scientists with the goal of bringing greater scientific rigor to the study of NDEs. While the effort itself has been widely praised, UVA researchers Bruce Greyson, MD, and Marieta Pehlivanova, PhD, argue that NEPTUNE does not succeed in explaining many defining features of near-death experiences.
Greyson and Pehlivanova, both affiliated with UVA’s Division of Perceptual Studies at the School of Medicine, published their critique in the journal Psychology of Consciousness: Theory, Research and Practice. Their response carefully examines the assumptions and evidence behind NEPTUNE and explains where, in their view, the model falls short.
What NEPTUNE Tries to Explain
NEPTUNE is designed as a unified neuroscientific model of near-death experiences. It attempts to combine insights from neurophysiology, psychology, and evolutionary biology into a single explanatory framework. According to the model, NDEs arise from extreme stress on the brain during life-threatening events such as cardiac arrest, trauma, or severe oxygen deprivation.
The theory suggests that changes in blood oxygen and carbon dioxide levels, surges of endorphins and neurotransmitters, and abnormal electrical activity in the brain could collectively produce vivid experiences that people later interpret as meaningful or even spiritual. NEPTUNE also draws on evolutionary psychology, proposing that some elements of NDEs may reflect ancient survival mechanisms designed to reduce fear and pain at the brink of death.
Greyson and Pehlivanova acknowledge that this is a serious and well-organized attempt to explain NDEs scientifically. However, they argue that the model selectively relies on evidence that supports its assumptions while overlooking findings that do not fit as neatly.
Why Hallucinations Don’t Fully Explain NDEs
One of the central claims of the NEPTUNE model is that near-death experiences are essentially a form of hallucination caused by physiological changes in the brain. According to the theory, altered brain chemistry during critical moments could generate vivid imagery and sensations.
The UVA researchers point out a major problem with this explanation. Typical neurological hallucinations usually involve only one sense, such as hearing voices or seeing shapes or lights. Near-death experiences, by contrast, are often described as multisensory. People commonly report seeing, hearing, feeling, smelling, and even touching things during an NDE.
Another key difference is memory persistence. Hallucinations caused by neurological conditions or drugs are often fragmented and quickly forgotten. Near-death experiences, however, are frequently remembered in extraordinary detail for decades and are often described as among the most meaningful events in a person’s life.
According to Greyson and Pehlivanova, this depth, coherence, and long-term impact does not align well with what is known about ordinary hallucinations produced by the brain.
The Debate Over Out-of-Body Experiences
Out-of-body experiences, or OBEs, are one of the most striking elements of many near-death experiences. People often report feeling separated from their physical body and sometimes describe observing their own body from an elevated perspective.
The NEPTUNE model attributes these experiences to activity in a specific brain region called the temporoparietal junction (TPJ). Previous studies have shown that stimulating this region can create sensations of disembodiment or altered self-location.
Greyson and Pehlivanova argue that this explanation does not hold up under closer scrutiny. In laboratory studies involving TPJ stimulation, participants may feel disconnected from their bodies, but their visual perception remains normal. They do not report seeing their physical body from above or moving freely through space, which are common features of OBEs reported during NDEs.
Additionally, electrical stimulation of the TPJ has produced visual distortions or hallucinations, but participants typically recognize these as illusions. In contrast, people who have near-death OBEs often report a strong conviction that the experience was real, not imagined.
The UVA researchers emphasize that no study has shown brain stimulation producing accurate perceptions of events outside the normal field of vision, especially when the eyes are closed or when the individual is clinically unconscious.
Gaps in Empirical Evidence
Beyond hallucinations and OBEs, Greyson and Pehlivanova raise broader concerns about the lack of direct empirical evidence supporting some of NEPTUNE’s core claims. While the model is theoretically detailed, it relies heavily on inference rather than direct measurement of brain activity during near-death experiences.
They also argue that NEPTUNE does not adequately account for reports of veridical perception, where individuals claim to have observed real events during periods when normal brain function should have been severely impaired. While such cases remain controversial, the UVA researchers believe they cannot simply be dismissed without careful investigation.
Acknowledging the Value of the Model
Despite their criticisms, Greyson and Pehlivanova are careful to acknowledge the value of the NEPTUNE project. They describe the work as a monumental effort that brings together a wide range of research and perspectives on near-death experiences.
Their concern is not with the goal of explaining NDEs through science, but with prematurely presenting a model as comprehensive when significant questions remain unresolved. They stress that the study of NDEs is still in its early stages and that open-mindedness is essential.
Why Near-Death Experiences Still Matter
Near-death experiences are more than just scientific curiosities. Many people report profound and lasting changes after an NDE, including reduced fear of death, increased compassion, and shifts in life priorities. These effects suggest that NDEs are not fleeting mental glitches but deeply impactful psychological events.
Understanding NDEs could offer valuable insights into human consciousness, the relationship between mind and brain, and what happens at the boundary between life and death. Even if neurophysiology plays a role, Greyson and Pehlivanova argue that current science does not yet have the tools to fully explain the phenomenon.
For now, the debate continues. NEPTUNE represents an important step forward, but as this latest critique makes clear, the mystery of near-death experiences remains very much unsolved.
Research paper: https://doi.org/10.1037/cns0000448
