As noted in previous posts, several physicians and neuroscientists have tried to explain near death experiences by making recourse to hallucinations and other possible physical triggers. But are near death experiences explained by science?
Dr. Mario Beauregard, neuroscientist at the University of Arizona, has responded to these physicalist explanations in his recent book, Brain Wars (2012a). His findings and responses have been verified by the Parnia et al. study which concludes that known physical explanations do not account for visual awareness, clarity of thought, and positive emotions associated with NDE’s.
The following is a brief summary of some of Beauregard’s responses excerpted from that book.
Blanke’s Induced OBE’s
Perhaps the most famous physicalist explanation of OBEs (out of body experiences) was proposed by Olaf Blanke in 2003 which received an accolade from the journal Nature claiming that Blanke’s research discovered the part of the brain in which OBEs are induced.
Blanke and his team placed electrodes in the angular gyrus of the parietal lobe which triggered an “OBE-like” experience in a 43-year old patient with epilepsy. She claimed that she had left her body, but could only see the lower half of her body – her legs and lower trunk.
As the experience progressed, she perceived her legs to be getting shorter and shorter. In 2004 Blanke and his team reported that they had induced an atypical and partial OBE in three patients and autoscopy in four patients – in which the patient perceives a double from the vantage point of her physical body.
Beauregard responds to this with van Lommel’s critique – first Blanke’s stimulations of the parietal lobe produce abnormal bodily experiences, and secondly these abnormal experiences give rise to a false sense of reality (e.g. legs growing shorter and seeing body doubles). These experiences are illusory whereas typical OBEs are not illusory.
Patients leave their body, and see (and accurately remember and report) what is going on inside the operating room and how their physical bodies are situated relative to the people, events, and instruments in that room.
Greyson adds to van Lommel’s criticism by noting that if we accept Blanke’s stimulations as typifying an OBE, we would be constrained to think that OBEs are illusions, but as we have seen throughout this chapter, there is nothing illusory about them – they give accurate descriptions of verifiable data almost all the time (only 8% minor inaccuracies according to Holden).
Susan Blackmore’s Anoxia Hypothesis
Beauregard then turns to Susan Blackmore’s hypothesis (1993) that anoxia (oxygen deprivation in the dying brain) could lead to the firing of neurons responsible for visual perception – possibly leading to an experience of a white light at the end of a tunnel.
Beauregard responds first with van Lommel’s criticism (2001) – that 100% of dying people suffer from anoxia; so if anoxia is the cause of near death experiences, 100% of patients should have them (but in fact only 18% of adults do).
Furthermore, the studies of Sam Parnia (2008 and 2014) show that several people have had near death experiences while feeling well – and therefore not suffering from anoxia.
Beauregard also looks into James Whinnery’s hypothesis that “dreamlets” are a possible explanation of NDE’s. “Dreamlets” occur in the stressed brain (e.g. of fighter pilots) immediately prior to unconsciousness.
This does not seem to be a plausible explanation of NDEs because Whinnery’s research indicates that these individuals wake up confused and anxious – instead of having lucid recollections and positive life-transforming experiences.
Narcotically Induced Hallucination
Beauregard then turns to the hypothesis of narcotically induced hallucination as a possible explanation of NDEs. Researcher Karl Jansen conjectured that he could produce an NDE by inhibiting NMDA receptors (by ingesting small quantities of ketamine – a veterinary anesthetic).
Though this did induce a sense of being out of body, the images in the hallucination were “weird” and perspectives were exaggerated. In contrast to this, patients having a near death experience perceive their surroundings in precisely the way they exist – e.g. inside the operating room (many of these perceptions have been verified by independent researchers after the fact).
Weak Transcranial Magnetic Stimulation
Another recent explanation has been offered by neuroscientist, Michael Persinger, who proposes that he too can stimulate an NDE by using weak transcranial magnetic stimulation (TMS) of the temporal lobes.
Beauregard, citing Greyson and the literature of epilepsy, shows that NDEs do not resemble the psychic states experienced by epileptic patients, and that transcranial stimulation of the temporal lobes does not result in experiences similar to NDEs, but rather in the psychic states associated with epilepsy.
In 2013 (after Beauregard’s book), Jimo Borjigin proposed another possible physicalist explanation for NDEs. During his experiments with rats, he discovered that a surge of electrical activity occurred in the brain (which he hypothesized might produce consciousness and an image) when rats experienced cardiac arrest.
This hypothesis is not on the same level as the ones mentioned above for three reasons:
- It was restricted to rats (not humans).
- There is no evidence that the electrical surge in the brain produced either consciousness or an image.
- Even if there were evidence that it produced consciousness and an image, there is no evidence that this consciousness-image resembles near death or out of body experiences.
In short, this hypothesis does not give researchers anything to compare to NDEs or OBEs – it is a pure speculation without an identifiable frame of comparison, meaning that it does not yet qualify as a scientific hypothesis.
In the next part, we will move on to discuss how neuroscience is not able to generate a credible physical explanation for the verified out of body phenomena in near death experiences by highlighting the major differences between NDEs and physically stimulated illusion.