Re: [asa] Question on recent OBE study, NDE

From: <drsyme@cablespeed.com>
Date: Fri Aug 24 2007 - 13:35:18 EDT

We need to be a little clearer on our terminology.

Even though it may have been a valid criteria in the past, the cessation of cardiac activity is no longer the most accurate definition of "dead."  So to say that someone who has had a cardiac arrest, even a flat line, is "clinically dead" is not exactly accurate.  Because of course they can be, in some cases resuscitated.  Unless you want to call CPR a resurrection, these people are NOT dead.  And it is very likely that people that are quickly resuscitated have not lost all brain activity.  But this could be difficult to measure.  The cortical neurons that are producing activity that would be accesible by an EEG would certainly show loss of activity quickly after cardiac arrest, if the person was being monitored by an EEG at the time, but that does not mean that there is not some ongoing subcotical activity, particularly thalamic activity, which might persist for some time after flat lining.  Of course all such activity would cease permanantly if resuscitation is not succesfull quickly after the arrest.

And even in the more accurate definition of death, that is brain death, loss of whole brain activity, does not necessarily mean that all brain function has ceased.  Brain death is merely a series of tests that indicate loss of cortical and subcortical brain function, from an irreversible cause, not necessarily that every neuron in the brain is not functioning.  For example central diabetes insipidus is a condition where the brain stops releasing ADH from a region of the brain called the hypothalamus, but in patients that are determined to be brain dead, DI is not typically a part of the clinical picture.

Since experiences very similar to NDE can be replicated by stimulation of depth electrodes, in the thalamus as I recall, my opinion is the NDE are due to ongoing thalamic activity after most cortical activity has stopped, after cardiac arrest. 



On Fri Aug 24 13:05 , Christine Smith sent:

See my responses below...

--- David Campbell <pleuronaia@gmail.com> wrote:

> > However, in a near-death experience (NDE),
> especially
> > those when a person has been declared clinically
> dead
> > (which as I understand it, means there's no brain
> > activity), am I correct in thinking that the
> findings
> > of this recent OBE study would not be applicable,
> > because the brain is not receiving and/or
> processing
> > sensory information (i.e. the person's eyes are
> > closed, there's no activity in regions of the
> brain
> > that would normally process such information)?
>
> I don't know how many of the stories are actually
> accompanied by solid
> evidence of lacking brain activity. The two
> examples I know of
> personally involved the emergency room personnel not
> anticipating
> survival, but no mention of specific assessment of
> brain activity. If
> the brain is not receiving normal stimuli, it can
> start to mistake
> other things for real sensory input. Of course,
> that doesn't explain
> why a particular set of coherent impressions would
> result, but it does
> suggest that there may be similar physical processes
> going on (even if
> the causative agent were a spiritual experience,
> presumably there must
> be some way of transmitting that into the neurons of
> the brain).
>
Aside from anecdotal stories (some of which, if true,
would be hard to explain scientifically I think), I
have found one study on-line that specified that the
patients were in a clinically dead state:
http://sedna.no.sapo.pt/death_scresearch/pdf_docs/sdm_nde.pdf,
with a rebuttal to skeptic Michael Shermer here:
http://www.skepticalinvestigations.org/whoswho/vanLommel.htm
(I couldn't find Shermer's critique on-line) I would
imagine there are probably others out there as well?

>
> My father's purported near-death experience might be
> of interest. No
> bright lights or voices, though. When he was
> hospitalized to drain
> excess pericardial fluid, a nurse saw the monitor go
> to a flat line
> and rushed in to find him sitting up and combing his
> hair. The flat
> line was merely due to a loose clip on the monitor
> wire, but I was
> able to point out that combing showed he had been
> de-parted.
>

How funny! :D

Christine

> --
> Dr. David Campbell
> 425 Scientific Collections
> University of Alabama
> "I think of my happy condition, surrounded by acres
> of clams"
>


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To unsubscribe, send a message to majordomo@calvin.edu with "unsubscribe asa" (no quotes) as the body of the message. Received on Fri Aug 24 13:35:32 2007

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