But first, let's establish the most common characteristics endemic to NDEs. Typical features in an NDE are: detachment from the body ( out-of-body experience); travelling through a tunnel (from dark to light); intense emotions (joy, love, peace); heightened and vivid perceptions; encounters with deceased loved ones and spiritual beings; life review, knowledge of ones purpose in life and a strong encouragement to return to earthly life.
There are occasional reports of negative NDEs but the overwhelming majority are positive.
1.Anesthesia Awareness Theory:
Dr. G Woerlee is probably best known for advocating the theory that Anesthetic Awareness can explain NDEs. This theory fails immediately because A.A only involves an auditory perception as well as painful, frightening and traumatic experiences. Contrasted with NDEs which are mostly pleasant, joyful and liberating. NDEs mostly involve visual perception, although auditory perception is possible, patients usually report being able to communicate and perceive information telepathically. The three most important key points to remember whenever A.A is propagated as an alternative explanation for NDEs are:
(i) The so-called relevant anecdotes which Dr. Woerlee and company picked out did not match the data.
(ii) A.A's and NDEs are vastly dissimilar experiences. The former being strictly auditory while the latter may include auditory, visual and telepathic perception.
(iii) NDEs causes the individual to adopt a healthy and optimistic approach to life, while A.A sufferers usually can't let go of their traumatic experiences and many end up committing suicide.
2. Hypoxia/Anoxia Theory:
A condition whereby the brain is being depleted by oxygen which is accompanied by an increase in carbon dioxide that are known to cause hallucinations especially among pilots. Dr. Kelly, a professor from Yale explains in his book Irreducible Mind: Toward a Psychology for the 21st Century some of the discrepancies between hypoxia symptoms and NDEs; "The primary features of acceleration-induced hypoxia, however, are myoclonic convulsions (rhythmic jerking of the limbs), impaired memory for events just prior to the onset of unconsciousness, tingling in the extremities and around the mouth, confusion and disorientation upon awakening, and paralysis, symptoms that do not occur in association with NDEs. Moreover, contrary to NDEs, the visual images Whinnery reported frequently included living people, but never deceased people; and no life review or accurate out-of-body perceptions have been reported in acceleration-induced loss of consciousness." [Page 379] [emphasis added by me]
3. The Ketamine/Medication Theory:
This theory can be easily refuted in four reasons:
(i) One cannot build a coherent theory of NDEs on a psychopharmacological basis because not all subjects were under medication, and in any case the effects of different drugs vary endlessly.
(ii) Another objection strengthened by the fact ketamine is no longer in general medical use, whilst subjects still continue to report NDEs.
(iii)The type of experiences induced by ketamine are mostly negative. Here's a list of some effects of ketamine:
- feeling happy and relaxed
- feeling detached from your body
- hallucinations
- confusion and clumsiness
- increased heart rate and blood pressure
- slurred speech and blurred vision
- anxiety, panic and violence
- vomitting
- lowered sensitivity to pain
*Note that two or perhaps three of the above effects are shared by NDEs. That does not even meet the standard for a preponderance of evidence.
(iii) Ketamine and most other anesthetic drugs were invented in the 20th century, despite the fact of reports that people were experiencing NDEs since the time of Plato.
4. Temporal Lobe Seizure (TLS) Theory:
Temporal Lobe Seizures are caused by abnormal electrical discharges in the brain, which may cause auditory and visual hallucinations. The Mayo Clinic lists the following symptoms:
- A sudden sense of unprovoked fear
- A deja vu experience — a feeling that what's happening has happened before
- A sudden or strange odor or taste
- A rising sensation in the abdomen
- Loss of awareness of surroundings
- Staring
- Lip smacking
- Repeated swallowing or chewing
- Unusual finger movements, such as picking motions
5. Residual Brain Activity Theory:
This theory came forward after a study done on rats which detected the presence of residual electric activity in dying rats. This study was also criticized by NDE researchers over here at IANDS, who concluded:
"There is ample evidence that consciousness is supported only by a certain minimal level of electrical activity. After the cardiac arrest, the rats do not have sufficient electrical brain activity to support consciousness. This conclusion is consistent with EEG studies in humans who experienced cardiac arrest and who immediately lost consciousness.So what do the highly coherent, global oscillations in the rats indicate? Most likely they are a natural oscillation that occurs in resonant neural circuits when the neural activity of the living rat has ceased. In other words, they are the remnant electrical activity of a dead brain"
Michael Prescott also points out on his blog some significant problems with the study:"Another possible weakness of the hypothesis is perhaps more easily tested. In the study, the rats' brains were monitored (using intracranial electrodes) throughout the waking state, anesthesia, and cardiac arrest (or asphyxiation). No surge was recorded during anesthesia. This has led some to argue that the surge cannot be responsible for an NDE, since NDEs do sometimes occur under anesthesia.In thinking about this, I wondered if we might be mixing apples and oranges. Broadly speaking, there are two kinds of NDEs (though there can be considerable overlap). The first kind are what might be called veridical or autoscopic NDEs, and are basically out-of-body experiences in which the person hovers over his physical body and observes what's happening around him. The second kind are transcendent NDEs, in which the person experiences a trip toward (or into) a bright light, reunion with deceased loved ones, a life review, and a decision (made by himself or others) to return to earthly life. Not all of these components are found in the typical transcendent NDE, but normally at least one of them is.
It seems clear that the veridical NDEs (or OBEs) cannot be associated with the electrical surge. Not only do such NDEs and OBEs occur under anesthesia, when there is no surge, but they also occur in other situations where the brain is not in any distress. It is even possible to learn to bring on such OBEs at will."
Feeling
detached from your body (‘falling into a k-hole - See more at:
http://www.druginfo.adf.org.au/drug-facts/ketamine#effects
Feeling happy and relaxed
On a final note: only a theory that can account for every commonly reported feature of the NDE will suffice as an entirely satisfactory, total neuroscientific explanation of the phenomenon.
Feeling happy and relaxed
Feeling detached from your body (‘falling into a k-hole')
Hallucinations
Confusion and clumsiness
Increased heart rate and blood pressure
Slurred speech and blurred vision
Anxiety, panic and violence
Vomiting
Lowered sensitivity to pain - See more at: http://www.druginfo.adf.org.au/drug-facts/ketamine#effects
Feeling happy and relaxed
Feeling detached from your body (‘falling into a k-hole')
Hallucinations
Confusion and clumsiness
Increased heart rate and blood pressure
Slurred speech and blurred vision
Anxiety, panic and violence
Vomiting
Lowered sensitivity to pain - See more at: http://www.druginfo.adf.org.au/drug-facts/ketamine#effects