Dr. Anders Sandberg comments in SMC on a recent PNAS study of rat neurophysiology following heart failure.

‘Surge of neurophysiological coherence and connectivity in the dying brain’ by Jimo Borjigin et al. published in PNAS on Monday 12th August.

“This is a nice experiment.  It is a simple and obvious test, and seems to be well done.  As the authors note, not much research has been done on brains suffering from heart failure – there might be many other important things to learn here, from a purely medical standpoint.

“EEG tells us things about brain activity a bit like listening at traffic noise tells you what is going on in a city.  It is certainly informative, but also an average of a lot of individual interactions.  And it is quite possible that different underlying situations can cause similar-looking brain activity.  So while particular brainwaves correspond to certain brain states in normal, healthy brains, it is not obvious they correspond to the same thing in a dying brain.

“Gamma waves have been linked to consciousness in various neuroscientific theories of consciousness.  The idea is that this fast rhythm helps synchronize different neural networks and bind their experiences together into consciousness.  There is plenty of debate about this, and many scientists and philosophers are unconvinced that this either works as an explanation (how does synchrony of your neurons actually make you experience something?) or that gamma waves imply consciousness (maybe they just imply that processing is happening, and that processing is what causes consciousness).

“A lot of the neural networks in the brain can stimulate themselves without any external signals under the right conditions – typically when regulation is not working well, like under the influence of drugs, tiredness etc.  And oxygen deprivation can certainly mess up many systems at the same time.  The gamma rhythm is also a bit of a ‘resonant frequency’: many parts of the brain tend to oscillate naturally at this frequency.  So it could be that during a NDE the conditions make neurons start to fire and form patterns of activity. These patterns of activity are shaped by how the brain is connected, and we know that some patterns in the visual cortex seem to closely correspond to commonly reported hallucinations (like tunnels).  Higher order parts of the brain might create emotions or ideas in a similar random fashion, populating the experience.

“No doubt some people will presumptuously claim that this is further evidence for life after death, which is doubly silly (near death experiences are in themselves just experiences).  But if one believes that, then one should also conclude the afterlife includes a lot of lab mice.”

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