| SOUL SEARCH (what is this?) A Scientist Explores the Afterlife David Darling 
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Now I am about to take my last voyage, a great leap into the dark.
– Thomas Hobbes, dying
There can be no one who doesn’t hope the near-death experience is a true prelude to a blissful afterlife. But when so much is at stake, it is surely right to question whether what may feel so overwhelmingly like a spiritual transformation is not in fact a very powerful illusion conjured up by the brain as it dies. We are not being cynical if we ask: Are there any theories that can adequately account for the NDE in a nonspiritual way?
One of the more imaginative attempts to come to grips with the NDE problem has been that of astronomer Carl Sagan. In his popular collection of essays, Broca’s Brain, he wrote:
The only alternative, so far as I can see, is that every human being, without exception, has already shared an experience like that of those travelers who return from the land of death: the sensation of flight, the emergence from darkness into light; an experience in which, at least sometimes, a heroic figure can be dimly perceived, bathed in radiance and glory. There is only one experience that matches this description. It is called birth.The tunnel, Sagan submits, is really a dim memory of the birth canal; the tunnel experience and the out-of-body experience are a reliving of one’s birth; and the Christlike figure bathed in light at the end is none other than the surgeon who draws us into the bright, postamniotic world. At first sight, these do seem to be striking parallels. But critics have exposed serious flaws in Sagan’s thesis. The birth canal would not really appear like a tunnel described in NDE’s, even if the fetus were looking forward and open-eyed into it – which it is not (its eyes are closed and its face is pressed against the wall of the uterus). Moreover, the passage through the canal could hardly be construed as being pleasant or peaceful. Considering that the fetus is rudely expelled from the warm security of the womb, is squeezed and squashed mercilessly for several hours, and finally has its skull bent out of shape as it is exuded like toothpaste down the canal, the birth experience is surely the very antithesis of tranquility. Nor is the obstetrician – the individual who hauls us out kicking and spluttering into a harsh new world – likely to be remembered in our final thoughts with fondness and goodwill!
More seriously, Sagan’s theory seems to demand far too much of the cognitive capacities of the unborn child. These are not such that it would remember the birth experience in a way that it would make sense to an adult many years later. Much has been made in recent years of so-called age-regression under hypnosis, which purports to show that subjects can recall incidents from around the time of their own birth and even prenatally. However, more carefully controlled studies have not been able to back up this claim. They suggest instead that, without realizing it, regressed patients simply make up experiences that seem superficially plausible.
Having said this, Sagan’s theory, like any good scientific theory, leaves itself open to testing. As Sagan himself pointed out, if the tunnel and out-of-body experiences are a rerun of birth, then there is one group of people who should never have them: those born by caesarian section. This straightforward test has now been done. Susan Blackmore, an experimental psychologist at the West of England University at Bristol, invited 254 people, of whom thirty-six had been born by caesarian, to fill out a questionnaire. The results seemed to demolish Sagan’s fascinating conjecture: both groups reported the same proportion of out-of-body and tunnel experiences.
An alternative explanation, favored by Blackmore and probably the majority of qualified scientists working in this field, is that NDE’s may be a particularly vivid form of hallucination. The origin of this theory can be traced back to the University of Chicago in 1926, where Heinrich Kluver had embarked upon a series of investigations with the hallucinogenic alkaloid mescaline. Derived from the peyote cactus, this drug has long been used among native Mexican Indian groups such as the Huichols as a purported aid to spiritual enlightenment. Kluver’s special interest, shared by a number of other researchers in Germany and the United States at this time, was the mental imagery induced by such hallucinogens. To this end, he experimented with the drug himself.
What Kluver found, and has since been confirmed, is that among the types of false perception brought about by mescaline are four relatively simple recurrent patterns. These are the honeycomb or lattice, the cobweb, the spiral and – a familiar structure – the tunnel.
Kluver went on to observe that these four form constants, the standard motifs of drug-induced imagery, were not just confined to mescaline or even to other hallucinogens such as tetrahydrocannabinol (the active principle of marijuana and hashish) and lysergic acid diethylamide (LSD). They cropped up again and again in a wide range of hallucinatory conditions, the list of which has been extended by other investigators to include epilepsy, migraine, psychotic episodes, advanced syphilis, sensory deprivation, oxygen deprivation, insulin hypoglycemia, falling asleep, waking, meditating and applying pressure to both eyes.
Is the tunnel so often reported by those who have come close to death none other than that seen by the peyote user or the migraine sufferer? But then, what of the bright light at the end of the tunnel? This, too, it turns out, is a common enough feature of hallucination induced by drugs and abnormal physical and mental states.
To understand how these hallucinations may come about we need to focus on that part of the brain in which mental images are formed. The visual cortex, located toward the back of the brain, handles both vision and visual imagination. In other words, it is capable of putting together pictures either from direct sensory input or from memory. Normally, the information arriving directly from the optic nerves takes precedence over internally generated imagery. What happens is that the neurons carrying the “real time” input of new data from the outside world inhibit other neurons from bringing previous perceptions and stored information to our attention. This is the normal or stable state of the visual cortex. During hallucination, however, the inhibitory mechanism is blocked, leading to an unstable and excited state.
To appreciate more clearly what happens, imagine a man standing at a closed window opposite his fireplace and looking out at the sunset. So absorbed is he by the view of the outside world that he fails to notice the weakly mirrored interior of the room. But as darkness falls outside, the images of the objects in the room behind him can be seen dimly reflected in the window. As darkness grows, the fire in the fireplace provides the main source of illumination, and the man now sees a vivid reflection of the room, which seems to be outside the window. The daylight (the sensory input) is reduced, while the interior illumination (the general level of arousal of the central nervous system) remains at a constant brightness. Because of this, images originating within the room (the brain) are perceived as if they came from outside the window (the senses).
Hallucinations occur, then, when some blocking agent interferes with the normal influx of sensory data. The hallucinations themselves are always there, like background noise in our mind. But we become aware of them only when the intensity of external images of dreams and daydreams is turned down.
Given the rich variety of possible hallucinogenic conditions, it seems at first surprising that hallucination should give rise to such a narrow range of basic visual forms. Why, for instance, the tunnel? What processes within the brain could generate such a structure? And, more to the point, how might its generation take place in a brain that is on the brink of death?
In 1982, Jack Cowan, a neurobiologist at the University of Chicago, furnished a valuable clue. Drawing an analogy from the way fluids behave, he argued that any sudden increase in cortical excitability would disrupt the brain’s normal state and cause “stripes” of activity to travel across the visual cortex. These stripes would be like the crests and troughs of ripples that spread out from a disturbance on the surface of a pond. What kind of mental imagery, Cowan asked, would such stripes give rise to?
Everything we see is represented first as a pattern of sensory rod and cone cells in the retina and then as a faithful copy of that pattern in different parts of the visual cortex. The entire picture is mapped from retina to brain by a complex mathematical function. Cown showed that because of the nature of the function, stripes of activity in the excited cortex would be perceived as though they were concentric rings, tunnels, or spirals in the world outside. Movement of the stripes would produce expansion or shrinking. Furthermore, because a much higher concentration of neurons is devoted to the center of the field of vision than to the periphery, a much greater effect could be expected in the center (assuming that all neurons were equally affected by the release from inhibition). This provides a natural explanation not only for the tunnel but for the brilliant light at the tunnel’s end. The crucial question remains: Is the near-death experience simply a hallucination?
One of the greatest challenges to the hallucination theory is to explain why NDE’s seem so remarkably real – far more real than the false imagery known to be generated, for example, by drugs or by oxygen deprivation. Many people are persuaded during NDE’s that the tunnel is a physical connection between this world and the next. The out-of-body sensation leaves them convinced that their spirit has fled their body and can sense and move around without it. The flood of positive emotion is so intense that many are genuinely upset and angry at having to return. Why do these experiences generate such powerfully realistic impressions?
As the American psychologist and philosopher William James pointed out: “What we perceive comes as much from inside our heads as from outside.” We take for granted that whatever we see and hear in our minds, as a result of our senses, is what is really “out there.” But it is not that straightforward. From the moment visual or auditory processing begins, incoming sensory data gets thoroughly mixed in with information already held in memory. That is all part of the process of making useful sense of the riot of signals that constantly bombards us. Out of the confusion, our brains extract and manufacture edges, textures, perspectives, objects, spaces, and other artifacts. But, this being so, how can we know what is real? How can we tell which aspects of the images we finally see in our mind’s eye came from outside and which have been constructed? The short answer is, we can never tell for sure. Nevertheless, the brain, from a survival standpoint, has to make a decision on what it thinks is real and what is not. A reasonable assumption is that the brain latches on to the most stable overall model of the world it has at any given time and calls that “reality.” In normal life the only model in contention, the only one that has the stability, coherence, and complexity to appear real, is the one built up from sensory input.
But what happens as we die? Where does the brain turn to for an acceptable model of reality when the senses start to shut down and internal noise threatens to overwhelm the higher centers of the nervous system? Maybe under these extreme conditions, the stripes of activity in the visual cortex are the most stable model the brain has left, so that the perception these stripes produce – of moving along a tunnel toward a bright light – inevitably appears real.
At the same time, being a superb survival machine, the brain might be expected to fight hard to stay in touch with events happening in the world outside. Some of the required information might continue to feed in through the senses, particularly the sounds of voices or those of bleeping monitors and other instruments. The powerful jolts from attempted resuscitation could supply further clues as to what was “really” going on. Using these limited sensory data as a starting point, a dying patient could flesh out the scene with images pulled from memory of, for example, a hospital emergency room (often realistically depicted on TV). And there is an interesting fact about memory models: they are often in bird’s-eye view. So, we have yet another possible natural explanation for a key element of NDE’s – the out-of-body experience.
If the way our memories store models really is the cause of out-of-body experiences, then people who have these experiences ought to have a better-than-average ability to imagine scenes from above. The same people might also be expected to recall and dream about things from a similar vantage point. Both these ideas have been supported in tests carried out by Susan Blackmore at Bristol and Harvey Irwin at the University of New South Wales, Australia.
As to the detailed life review often experienced during an NDE, this too can be partially accounted for. During the course of operations in the 1950s intended to cure people with severe epilepsy, Canadian surgeon Wilder Penfield passed a gentle electric current through electrodes touching specific parts of the visual cortex. The results were startling. Patients (who were only locally anesthetized) suddenly remembered scenes and events from the past in startling detail. The electrical stimulation seemed to trigger not just a normal recall but an apparent reliving of the event, complete with authentic sights, sounds, and smells. As soon as the current was shut off, the induced recollection was immediately lost. But it could often be resumed once more by stimulating the same area. Interestingly, the recall did not pick up where it had left off but started again at the beginning, as if it were stored on videotape that rewound itself each time it was interrupted. This suggests that a record of incidents from our life is stored subconsciously in quite remarkable detail and that it can be brought to our awareness under the right conditions of stimulation. Conceivably, the waves of cortical activity that might produce the tunnel experience might also trigger the rapid playback of our archived personal histories.
Finally, there is the meeting with other beings, including the “Being of Light,” to be addressed. This is perhaps the least problematic of all the elements of the experience. Surveys of NDE subjects from different cultural backgrounds, such as those conducted by Bruce Greyson, a psychiatrist from the University of Michigan Medical Center, have revealed a marked variation in the type of encounters that take place. Those of an orthodox Christian persuasion often recognize the brilliant light source as being Jesus, although the archangel Gabriel and Saint Peter are sometimes cited. Hindus more frequently meet up with some kind of messenger, who consults a list of names. Having concluded that a wrong person has been called up, the messenger gives a reprieve. An African doctor, Nsama Mumbwe of the University of Zambia, recorded this account from an eighty-five-year-old grandmother:
“I was suffering from a stroke. During this time I felt I was put into a big calabash [an empty gourd shell] with a big opening. But somehow I couldn’t get out. Then a voice from somewhere said to me, ‘Be brave. Take my hand and come out. It is not yet your time to go.’Accounts like this are reminiscent of tales told to young children. And that may be exactly what they are. If the brain believes it is dying, what could be more natural than in its final moments it should call up its most firmly entrenched notion of the afterlife – the one laid down when we are most impressionable, in early childhood? Beautiful gardens, smiling people in white robes, reunion with deceased loved ones, a fatherly, all-embracing God – these are all pictures painted for us by our parents in our formative years. Even professed atheists probably have a stereotyped image of Saint Peter standing at his pearly gates tucked away somewhere in the attic of their minds. Likewise, people of other cultures and faiths will encounter the beings who populate their afterlife myths.
“After some time of being in the calabash I managed to get out on my own.
“I believe someone was trying to bewitch me, but found that I was an innocent soul.”
Materialists and skeptics, then, are not dumbfounded by the near-death experience. They would argue persuasively, in fact, that a theory based on hallucinations goes a long way toward explaining most of the mysteries of the NDE.
Critics of this theory hark back to the superrealism of the NDE, which sets it apart from all previously known types of hallucination. They point also to the permanent, life-transforming effect of the NDE, which is often akin to a religious conversion. These arguments, though, are not entirely convincing. A person near death is in the most extreme condition imaginable, so that any perceptions received at that time – hallucinatory or not – could be expected to seem extraordinarily vivid and memorable. This, combined with the subconscious anticipation of some kind of momentous, final event, which probably most of us have had hard-wired into our brains from early childhood, could well be enough to produce an overwhelming and permanent impression.
The hallucination theory, moreover, draws upon only what we already know to be true, or can easily surmise, about the way the brain works. A general guiding principle in science, known as Occam’s razor, is that new concepts should not be brought in unnecessarily: all things being equal, the preferable of two theories is the simpler. Why go out of our way to speculate that NDE’s offer proof of life after death if we already have in our grasp a good working explanation based on more commonplace phenomena?
Frankly, it is very easy to persuade large numbers of people, through emotive anecdotal tales, that the afterlife theory is right – because that is what everyone wants to believe. But we run the risk of being crushingly disappointed (as the believers in spiritualism were) if we place too much personal stock in the afterlife interpretation of NDE’s and then find this is undermined by future research.
Yet the idea that NDE’s are mere concoctions of the dying brain is far from being home and dry. Two particular pieces of evidence would, if substantiated, be difficult to reconcile with the theory of hallucinations.
Among others, Michael Sabom, a cardiologist from Atlanta, has claimed that patients have seen things during NDE’s that they could not possibly have reconstructed from auditory cues or from what they may previously have known about resuscitation techniques. One of the anecdotes he refers to is about a shoe seen on an inaccessible window ledge by a person while she was supposedly out of her body. Other stories tell of patients recalling the positions of needles on medical instrument dials and the detailed appearances of doctors and nurses during the time of the NDE. Sabom asked a group of volunteers who had never had a near-death experience to imagine going through a resuscitation procedure and to tell him what they saw in their minds. The accounts, he claims, were nothing like the accurate descriptions of apparatus or the readings on instruments that NDEers report having seen from out of the body.
The other piece of evidence that seems to cast doubt on the hallucination theory comes from instances in which an electroencephalograph, or EEG, was connected to patients during the time of their NDE. The results seem to suggest that out-of-body experiences may have happened while the EEG readings were completely flat, that is, while there was no measurable brain-wave activity of any kind. The hallucination theory requires that the brain be active in generating an NDE.
How are these remarkable claims to be addressed? First, concerning Sabom’s work, there are loopholes in his experimental procedure. Since the members of the control group were not subjected to the same resuscitation procedure and actions of the staff, any comparisons drawn between them and NDE patients carry limited value.
Also, it has so far proved virtually impossible to confirm or deny any of the often-quoted stories of patients seeing things while supposedly out-of-body. Investigators such as Susan Blackmore tried, only to find that the trail had gone very cold. The patients either had since died or were confused about the exact details of their experiences, doctors and nurses were equally uncertain as to what had actually happened, and there were very few records of instrument readings or procedures carried out at the time. This is not to imply that anyone has tried to mislead, only that anecdotal tales have to be treated with the greatest caution. Many of the best selling books about NDE’s are packed with such unverifiable accounts, as if their repetition strengthens the case for an afterlife interpretation. It does not.
Formidable problems exist in collating the subjective information given by patients with reliable and accurate objective data from the scene. In the first place, no one can predict when an NDE is going to happen, and it is obviously not feasible for doctors and other staff (most of whom are dismissive of NDE’s anyway) to be on constant alert for the phenomenon. The attendants’ main concern, in any case, is to revive the patient, not to take notes on the circumstances of the event. And finally, after an NDE is reported to have taken place, it is impossible to tell exactly when it happened since the patient who underwent the experience had no access to a clock. In short, in the case of every NDE described to date, we have little more than second- or third-hand fireside tales and irreproducible data.
As for the EEG evidence, there is a general problem with the sensitivity of these machines, especially at low levels of brain activity. EEG’s occasionally pick up spurious signals (through interference) when they are not even connected to a living brain. In one test, for instance, Jell-O gave positive readings. Conversely, there have been times when EEG’s sensed no brain-wave patterns in patients who, from other vital signs, were known to be alive. The brain activity can be going on at such a deep level that electrodes on the surface of the scalp fail to pick it up. And, again, there is the difficulty of correlating the period of the flat trace with the time during which the NDE took place.
Physicians and psychologists who have written on the near-death experience make much about the tunnel, the out-of-body sensation and especially the Being of Light. These effects, as we have seen, are not impossible to explain in terms of universal processes that happen in the dying brain.
However, there is one aspect of the NDE that we have not yet dealt with but that poses an enormous problem for the materialist. It is hard for the person who feels it to describe. It seems to go beyond words. But what it apparently consists of is an extraordinary deepening and broadening of consciousness as ordinary life comes to an end. Coupled with this increase in overall consciousness is a progressive lessening of self-awareness. As the experience unfolds, the subjects, it seems, become more and more conscious of everything except themselves.
This is the core enigma of the NDE. Why should it be that as the brain dies, consciousness expands? And why should it be that as consciousness expands, self-consciousness disappears?
This much is certain: for those who have made the journey to the netherlands of life, the effect is profound. Whatever may lie behind the NDE – whether it is truly evidence of life after death or a mere artifact of the dying brain – makes no difference in one important respect. The NDE is life-transforming. For a while, at least, other worlds appear on an equal footing with our own – as real as the familiar reality we thought unique. The body is seen to be of little consequence, and for some who go through the process all sense of being an individual is lost. Indeed, the NDE reveals something quite astonishing about the human condition. It affords a disturbing peek into the artificial nature of self and the world: neither can seem so substantial again.