Anesthesia, EEG versus CBF

[Dave casarino]

Even after my debates on the previous incarnation of this forum I am still perplexed as to the dismissal of anesthesia as a thorn in the side of idealism by most debaters on this forum. Whilst I did state before in my previous post in this new forum that there is people under low doses of anesthesia whom act conscious whilst under whom do not remember a damn thing despite being conscious, thus the subject of memory becomes a big problem for an anesthesia based attack on idealism. However I still find articles on anesthesia rather problematic for idealism https://neurosciencenews.com/consciousn ... oss-13009/ this article discuses anesthesia's ability of both micro and macro disconnect between firing neurons whilst this lay article discusses the dominating wave oscillation correlation to anesthetic induced unconsciousness https://www.vice.com/en/article/d3489z/ ... anesthesia

But the real debate starts here: reading this technical article https://www.frontiersin.org/articles/10 ... 00039/full in conjunction with it's figure https://www.frontiersin.org/files/Artic ... 9-g001.jpg when common anesthetic propofol is inducted slowly into a patient we are told: "When blood (and consequently effect-site) concentration of propofol slowly increases, patients are gradually sedated and finally lose responsiveness. When awake or during light sedation, EEG shows quite small and high frequency (Figure 1A). Electromyogram (EMG) contamination is often observed at this level. Just after loss of response, fast waves with small amplitude still predominate, but their frequency is slower than during wakefulness. Alpha power is quite small at this level (Figure 1B). As propofol Ce increases, EEG frequency slows and EEG amplitude becomes larger, whereupon alpha waves becomes dominant (Figure 1C). This waxing and weaning spindle wave pattern is observed during stage II of slow wave sleep. During sleep, spindles emerge only transiently, but are observed continuously during anesthesia induced by propofol or volatile anesthetics. When propofol Ce increases further, alpha waves become smaller and theta and delta waves become dominant (Figure 1D), eventually, the burst-suppression pattern emerges (Figure 1E)." However during rapid induction of Propofol or Thiopental we are told "Observation of raw EEG, however, during rapid induction is quite specific. Just after loss of response owing to bolus administration of propofol or thiopental, large delta waves emerge. At that time the BIS™ index decreases to 20–30 (Figure 1I). Similarly, during slow induction by 8% sevoflurane, similar waveforms may also be transiently observed and the BIS™ index may decrease to 10–20 (Yamaguchi et al., 2003). Soon after that, alpha or theta waves predominate and BIS™ index increases to 30–50."

Bernardo Kastrup often makes the argument that psilocybin is proof of his theory in that it lowers CBF in the brain whilst increasing phenomenal experience as we see here https://www.pnas.org/content/109/6/2138 but what of brain waves and EEG? EEG measures brain waves and said brain waves are indicative of certain brain activity https://choosemuse.com/blog/a-deep-dive ... plained-2/ in this article here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5616440/ we are told "Psilocybin decreased the EEG spectral power in alpha frequency band, however increased the power of gamma oscillations. The LORETA analysis revealed the source of decreased alpha in midline parietal structures and occipital lobes. The increase in higher frequencies was pronounced in large temporal areas. EEG findings will be correlated with neuropsychiatric scales." This states that psilocybin INCREASES certain forms of brain activity in contrast to the CBF focused article Kastrup cites. I tried to find articles discussing CBF under anesthesia but most of the technical articles were too topic pointed and so thus I could not gleam accurate information that was consistent to make any kind of point in that regard. So is Kastrups mushroom based argument inconsistent with EEG? Is CBF more telling of brain function than EEG? I hope after careful consideration of my sources we can continue the discussion on anesthesia which I still believe is of relevance to any argument based on the primacy of consciousness. Do you believe these points challenge idealism? If not why? All quotes are from the articles listed and were written by their authors.

[Jim Cross]

You might want to tell everyone who might not know what CBF is. Cerebral blood flow? Is that what you mean?

My opinion is EEG is telling more about brain function but CBF can isolate better where in the brain the activity is occurring.

Anyway, sorry to tell you, but you are wasting your time with this argument. Most people on this forum think that even completely dead brains are conscious.

[Astra052]

Someone who I think talks about this issue really well is neuroscientist Dr James Cooke. He is a physicalist who has his own theory of consciousness, he's not an idealist but he disputes the idea tha anesthesia really can be used as an arguement to say consciousness stops. He argues that anesthesia probably disrupts memory systems and various forms of communication in the brain that make it (if all goes well) impossible for there to be a reported experience. It's not that consciousness is turned off, however the effect makes it seem as if it is. Really a lot of this stuff is very unknown as much of the brain is and EEGs really aren't as reliable as you'd expect. You're making a valid argument, I just don't think we understand the science well enough yet to really form convincing arguments on either side.

[Soul_of_Shu]

Most people on this forum think that even completely dead brains are conscious.

Nonsense, as according to BK's model not even a living brain is conscious, but a phenomenal representation of 'ideation' appearing within consciousness, and no more conscious than the textual forms playing on this screen, they being representational of this mind's ideation.

[Eugene I]

What, again? I though we discussed it all on the old forum.

Anesthesia may be a state of the absence of consciousness. But anesthesia may also be a state of the continuation of consciousness with the interruption of memory function. Diminished or absent EEG activity (or CFB) can only be an evidence of the absence of consciousness if we accept an assumption that consciousness is a direct product of neural activity, or if it is at least 100% correlated with neural activity. If we do not make such assumption, the above scientific data prove nothing, and there is no way to prove or disprove the continuation of consciousness based on any EEG/CFB data. Idealism simply does not accept such assumption, therefore the above data is irrelevant as a proof or evidence of the discontinuity of consciousness. Under idealism, consciousness is uninterruptable, however, a particular state of consciousness may have certain correlations with the neural states, yet the correlation does not have to be 100% (and it can be anywhere between 0% and 100%). Since the correlation is not 100%, the interruption of consciousness can not be proven by the data of neural activity, which means that the idealism assumption of the continuity of consciousness is experimentally non-falsifiable.

[5MeO-DMT_Philosopher]

https://1.bp.blogspot.com/-QFq4e-0flo0/ ... .large.jpg

Yes, it's not only CBF but also delta, alpha, theta, and beta brain waves
However, I'm not sure about gamma brain waves as they usually don't measure them
Here: https://www.researchgate.net/publicatio ... 27-29_2018

5-MeO-DMT induced Gamma power increase. As well as in this video they measured an increase in gamma brain waves after vaporized 5-MeO-DMT

[Eugene I]

NDE studies provide additional data on the lack of 100% correlation between consciousness activity and measurable cerebral function and suggests that consciousness can continue with full memory function is the absence of any measurable EEG signals.

Among 2060 CA events, 140 survivors completed stage 1 interviews, while 101 of 140 patients completed stage 2 interviews. 46% had memories with 7 major cognitive themes: fear; animals/plants; bright light; violence/persecution; deja-vu; family; recalling events post-CA and 9% had NDEs, while 2% described awareness with explicit recall of ‘seeing’ and ‘hearing’ actual events related to their resuscitation. One had a verifiable period of conscious awareness during which time cerebral function was not expected.

[Jim Cross]

Most people on this forum think that even completely dead brains are conscious.

Nonsense, as according to BK's model not even a living brain is conscious, but a phenomenal representation of 'ideation' appearing within consciousness, and no more conscious than the textual forms playing on this screen, they being representational of this mind's ideation.

Even better reason for Dave not to bother about anesthesia arguments. The live, awake brain can never become unconscious but it was never conscious in the first place.

[Eugene I]

The live, awake brain can never become unconscious but it was never conscious in the first place.

More precisely, in idealism, there was never any brain in the first place, neither conscious nor unconscious, there was only an image of it.

[Ben Iscatus]

Even more precisely, there is a brain, which is the image (as interpreted by evolved senses) of a dissociated mind.