Psience Quest

I thought this was

Hi, Max

The letter you've posted above is based on an incorrect premise and the authors they quoted (Dhanani et al) retracted their statements several months ago. See here :

"The authors conclude that the recording is a false reading and cannot be assumed to indicate that the brain is still functioning."

http://blog.journals.cambridge.org/2017/...ac-arrest/

I posted this on Sleptiko (months ago) in response to a previous post you made on the same subject. Hopefully this will clear the matter up.

(2017-08-27, 11:35 AM)Max_B Wrote: [ -> ]Yes, the author of the letter disagreed with some of the conclusions of that pilot study. Their reasoning and references are not only interesting, but solid and sound.

We've been through all this before, Max. It can't go anywhere because once the brainstem is knocked out (as in cardiac arrest) the whole caboodle goes down. Even Woerlee admits this. It's just a fact about how the brain works, no blood, no glucose and oxygen, no fuel to power the brain cells (neurons) so everything stops.

(2017-08-27, 03:00 PM)Max_B Wrote: [ -> ]Well everything doesn't stop within the brain a few seconds into cardiac arrest, that's the point. The referenced paper [3] above is one of many which show that firing can continue for some time beyond 20 seconds of energy compromise, quite a few minutes actually, depending on the type of cells and their location, and whether or not CPR is started, and it's quality.

"Well everything doesn't stop within the brain a few seconds into cardiac arrest, that's the point."

I didn't say it did, Max, I said it stops on average after 20 seconds. The paper above is irrelevant now, the author has admitted that.

(2017-08-27, 03:51 PM)Max_B Wrote: [ -> ]I think your getting muddled up with some other paper... Brisson et. al. 2013 shows activity is possible well beyond 20 seconds, a few minutes at least.

Please can you show me the paper ?

(2017-08-27, 04:38 PM)Max_B Wrote: [ -> ]A Distinct Boundary between the Higher Brain’s Susceptibility to Ischemia and the Lower Brain’s Resistance

Abstract

Higher brain regions are more susceptible to global ischemia than the brainstem, but is there a gradual increase in vulnerability in the caudal-rostral direction or is there a discrete boundary? We examined the interface between `higher` thalamus and the hypothalamus the using live brain slices where variation in blood flow is not a factor. Whole-cell current clamp recording of 18 thalamic neurons in response to 10 min O2/glucose deprivation (OGD) revealed a rapid anoxic depolarization (AD) from which thalamic neurons do not recover. Newly acquired neurons could not be patched following AD, confirming significant regional thalamic injury. Coinciding with AD, light transmittance (LT) imaging during whole-cell recording showed an elevated LT front that initiated in midline thalamus and that propagated into adjacent hypothalamus. However, hypothalamic neurons patched in paraventricular nucleus (PVN, n= 8 magnocellular and 12 parvocellular neurons) and suprachiasmatic nucleus (SCN, n= 18) only slowly depolarized as AD passed through these regions. And with return to control aCSF, hypothalamic neurons repolarized and recovered their input resistance and action potential amplitude. Moreover, newly acquired hypothalamic neurons could be readily patched following exposure to OGD, with resting parameters similar to neurons not previously exposed to OGD. Thalamic susceptibility and hypothalamic resilience were also observed following ouabain exposure which blocks the Na+/K+ pump, evoking depolarization similar to OGD in all neuronal types tested. Finally, brief exposure to elevated [K+]o caused spreading depression (SD, a milder, AD-like event) only in thalamic neurons so SD generation is regionally correlated with strong AD. Therefore the thalamus-hypothalamus interface represents a discrete boundary where neuronal vulnerability to ischemia is high in thalamus (like more rostral neocortex, striatum, hippocampus). In contrast hypothalamic neurons are comparatively resistant, generating weaker and recoverable anoxic depolarization similar to brainstem neurons, possibly the result of a Na/K pump that better functions during ischemia.

Thanks, Max. For a start it doesn't say how they got these readings, or from what creature, alive or just dead and it doesn't say whether the creature is in cardiac arrest or not (does it ? apologies if it does)  

"Whole-cell current clamp recording of 18 thalamic neurons in response to 10 min O2/glucose deprivation (OGD) revealed a rapid anoxic depolarization (AD) from which thalamic neurons do not recover."

That statement is perfectly in line with what I've posted previously. What you're getting at here I think is that these authors think they have found that the neurons in the hypothalamus retain their electrical potential slightly better than the neurons in the thalamus. I'm not a neuroscientist but it wouldn't surprise me as it just means that the hypothalamus is deeper inside and possibly the last bunch of neurons to stop and eventually burst.

It's tiny portion of the brain partly responsible for many important functions. Consciousness is not one of them. If you cut off the blood supply to the brain, the brain stem stops functioning. When doctors are able to determine that the brainstem is badly damaged (in coma) that is all they need to know as regards whether or not there is anything meaningful going on. But coma isn't as severe as cardiac arrest.

I don't see how you can make a case for a tiny area of the brain being responsible for lucid cognition with reasoning and memory formation as occurs in NDE, when the reflexes of the brain that should underpin such experience are just not there (apparently according to medical orthodoxy)

(2017-08-28, 07:01 PM)Max_B Wrote: [ -> ]Yes, that's right. After the brain is starved of oxygen and glucose, it's possible for different cells from different structures in the brain to continue to function for longer than than medical EEG can measure EM activity from cortex cells. A good few minutes longer according to the results in this paper.

I don't think there is any way to falsify that assertion. It may well be that some neurons deep in the brain still have electrical potential across them after a few minutes, I don't know.

What is known is that the detectible activity that is presumed to be responsible for the creation of the mind disappears after approximately 20 seconds along with the reflexes of the central nervous system.

The brain stem

The brain stem is the lower part of the brain that's connected to the spinal cord (part of the central nervous system in the spinal column).
The brain stem is responsible for regulating most of the body's automatic functions that are essential for life. These include:

• breathing
  
• heartbeat
  
• blood pressure
  
• swallowing
  

The brain stem also relays information to and from the brain to the rest of the body, so it plays an important role in the brain’s core functions, such as consciousness, awareness and movement.

After brain death, it's not possible for someone to remain conscious.
How brain death occurs
Brain death can occur when the blood and/or oxygen supply to the brain is stopped. This can be caused by:

• cardiac arrest – when the heart stops beating and the brain is starved of oxygen
  

(2017-08-29, 02:08 PM)tim Wrote: [ -> ]The brain stem is responsible for regulating most of the body's automatic functions that are essential for life. These include:

• breathing
  
• heartbeat
  
• blood pressure
  
• swallowing
  

Isn't it already clear that none of these things are happening during cardiac arrest? If it isn't able to carry out these basic functions, how could it do something vastly more complicated?

(2017-08-29, 02:18 PM)Typoz Wrote: [ -> ]Isn't it already clear that none of these things are happening during cardiac arrest? If it isn't able to carry out these basic functions, how could it do something vastly more complicated?

Precisely, Typoz.  Succinct and spot on.

There is no meaning to the phrase the "brain being dead". There is no definition of such a thing.

More to the point- even if the brain shows some sort of electrical activity for a few seconds or even a very few minutes after cessation of heart activity, so what? Can anyone make a reasonable claim that high level brain function can happen in such a state? Of course not. 

This whole line of inquiry is pointless, and only serves as a shiny object that skeptics can point to in order to avoid the heart of the matter, which is: how can one have an ultra-real experience while the brain is totally non-functional or at least profoundly diminished? 

This is the core of why Eben Alexander, who is a brain surgeon after-all, unequivocally stated, based on his own personal NDE (or call it a close-to-death experience if you like), that the seat of our life experience, and consciousness itself, is clearly NOT in our brain.