"The most beautiful thing we can experience is the mysterious" ~ Albert Einstein

Wednesday, September 18, 2013

Study on Rats Proposes a Mechanism for NDEs

Quite frequently a new study will come out purporting to explain Near Death Experiences (NDEs).  These are typically attempts to explain NDEs as some aspect of a dying brain.  If you're a staunch materialist, I guess it really is the only reasonable way to view the NDE phenomenon.  But, almost all of these fall short of explaining most aspects of the NDE phenomenon.  Some can even get pretty darn silly.  One claimed, "many of the phenomena associated with near-death experiences can be biologically explained", which was done by comparing different aspects of NDEs to various common and uncommon disorders.  Quoting just some of the disorders they used, I facetiously summed up their analysis of NDEs in the following manner.

"So, basically, if I happen to simultaneously have Cotard's syndrome and Parkinson's disease, while suffering from interrupted sleep patterns, while tripping on acid and become afflicted with some strange eye problems, it then becomes possible for me to have an NDE?"

However, a study came out recently that was pretty interesting.  They found highly coherent, global oscillations in the brains of dying rats.  (yes, they killed the poor little guys).  I planned to write something up on this, but I noticed Robert Mays of the International Association of Near Death Studies (IANDS) wrote up an article, which is probably better than anything I would write and he is far more qualified to discuss the issue.  So, I will just quote the contents of that article below and provide a link.




I would add one extra flaw to his list.  One cannot actually ask the mice if they had an NDE.  I think this is especially important, given that the level of electrical activity found would not normally be sufficient for normal waking consciousness, let alone a hyper-real lucid experience that is reported in NDEs.

Nonetheless, I've said for a long time that even if NDEs are a result of consciousness becoming free of the brain (I discuss this "filter" model of the brain in this blog post), certain aspects of the NDE may be modulated by the dying brain, or by trauma to the brain.  So, if any electrical activity is found during a period when an NDE is suspected to occur, it must be investigated and may provide some insight into the NDE experience and to what extent it is modulated by the brain.  Clearly, it should have nothing to do with the veridical aspects, or the hyper-real lucid states of consciousness that are reported.  Eben Alexander mentioned the Earth-Worm Eye view aspect of his NDE (again discussed in the post linked above) may have been the best consciousness his meningitis-ridden, pus-soaked brain could put out.  Perhaps, similar aspects of his and other NDEs are modulated by the brain, at least partially.  However, this is just my idea, which doesn't seem to be widely supported, so take it with a grain of salt,

Anyhow, here's the content of the May's article (links provided below)

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"A recent study by Jimo Borjigin and colleagues (University of Michigan) reports that highly coherent, global oscillations in the brains of rats occurred from about 12 to 30 seconds after cardiac arrest. The investigators found that near death, some of the electrical signatures of consciousness exceeded levels found in the waking state, providing "strong evidence for the potential of heightened cognitive processing in the near-death state." "The measurable conscious activity is much, much higher after the heart stops." They assert that this evidence provides "a scientific framework to begin to explain the highly lucid and realer-than-real mental experiences reported by near-death survivors."  

How well do these assertions hold up to scrutiny?

Commentary by Robert Mays, NDE researcher
 
There are three major flaws in the reasoning that the University of Michigan researchers used. The first flaw is that a near-death experience, with its elements of the sense of being out of the body, feelings of peace, hyper-real lucid sensations and mentation, and so on, occurs only when an individual is near death. It's important that any explanation of the phenomenon of NDEs explain the broad spectrum of cases in which they occur. NDEs can be triggered by cardiac arrest or a physical trauma, but they can also be triggered by an accident in which the NDEr is not hurt and even in a healthy individual who experiences an NDE spontaneously.

Furthermore, shared-death experiences provide even further evidence where a healthy person at the bedside of a dying loved one experiences many of the same elements of the NDE (see Moody and Perry, Glimpses of Eternity, 2010).

There is no physiological explanation of NDEs and SDEs that can explain the variety of trigger conditions and elements of the experience. So while the results of Dr. Borjigin and colleagues are interesting, they do not provide a scientific framework for explaining NDEs.

The second major flaw in reasoning has to do with the assumption that coherent oscillations in widely separated regions in the brain constitute a general signature of consciousness. In fact, coherent oscillations are neural correlates of consciousness, but are specific to cognitive activity that is directed toward a particular task such as visual spatial attention or directed motor activity. The oscillations tend to be transient, lasting only a few hundreds of milliseconds and the brain regions involved are related to the cognitive task at hand.

In fact the transient pattern of coherent gamma oscillations (25-55 Hz) that were observed in the awake rats in this study prior to anesthesia is typical of consciousness. The coherent oscillations are only a small part of the overall picture of the rat's consciousness. Coherent gamma oscillations are indications only of specific, directed cognitive activity rather than general consciousness. These oscillations always occur in the context of other electrical activity that indicate general consciousness. Thus the result that the gamma oscillations increased significantly in the period after cardiac arrest is not an indication of a heightened general consciousness.

Finally, the third major flaw is that the researchers discounted or ignored the overall power of the electrical activity in the awake rat, where there is clearly consciousness, compared with the greatly reduced power of electrical activity after cardiac arrest. The overall power of electrical activity in the conscious rat is more than 30 times greater than after cardiac arrest. (This is an estimate since I do not have access to the specific data).

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."





IANDS Article: Study on rats proposes a mechanism for NDEs 

 

Original Paper:  Surge of neurophysiological coherence and connectivity in the dying brain

 

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