Anesthesia, EEG versus CBF

[SanteriSatama]

Anesthesiologist Stuart Hameroff has given anesthesiological evidence against the reduction to classical physics. I don't remember the exact details, it's been long since I read the stuff, but I suppose they can be found on his web site. I don't think Orch-OR is especially strong candidate even in the field of quantum mind theories, but any case better than standard materialism of reduction to classical physics.

Whether idealism or some quantum version of neutral monism, or something else, we've still a long way from a coherent theory that involves and integrates quantum theory in some theory of mind. I think the main problem remains on the side of QM, as the development of the quantum theories and interpretations has created unsustainable tensions with the mathematical base they started from. I'm not the first to suggest that QM needs a new theory of math, many have been saying that for quite a while.

[Soul_of_Shu]

While not about the NCCs associated with psychedelic experience, but still being related with respect to reduced or absent NCCs associated with heightened/expanded awareness, such as in OBE reports described in NDE events, a new book just recently out, titled After: A Doctor Explores What Near-Death Experiences Reveal about Life and Beyond by Dr. Bruce Greyson, may well be the most extensive investigation ever done into the topic, which may be of interest here ... Also there are various interviews and presentations with him available online.

[Soul_of_Shu]

FYI, if interested in an interview with Dr. Bruce Greyson the one I'd most recommend would be this one ...

[5MeO-DMT_Philosopher]

While we replicated previous findings concerning decreased power in the alpha band [4–11], including work showing that this depends on 5-HT2A receptor stimulation [9], some discrepancies appeared in the time course of alpha power changes after DMT inhalation in the present study. Reduced alpha power manifested most strongly immediately after DMT administration, and gradually receded towards baseline values after approximately 7 minutes. In contrast, previous work by Timmermann and colleagues reported that reports of subjective effect intensity were reduced to half of their peak value after 7 minutes and that alpha rhythm amplitude did not completely recover until approximately 15 minutes after the injection of doses ranging between 7 mg and 20 mg DMT fumarate [11]. These differences in the time course of alpha power reductions could be attributed to different pharmacokinetics between inhaled and intravenous administration routes, with some reports suggesting an equally rapid onset but shorter duration in the case of inhaled DMT [64]. Another possibility is that the effective dose in our study was lower than the doses employed by Timmermann and colleagues. Even though we did not quantify DMT content in the smoked samples, participants and facilitators declared a typical dose of 40 mg, in all cases extracted from Mimosa hostilis bark following a standard acid-base extraction procedure [81]. Previous analysis of similar DMT samples showed an average purity of 85% [82], which would imply an average dose of 35 mg in our study, comparable to the maximum dose used in Timmermann, et al. (2019) when one considers brain availability from an inhaled dose vs. intravenous administration. While smoked and intravenous DMT are both more potent than intramuscular injections [83], more research is required to establish a more precise correspondence between these two routes of administrations. A third possibility is that subjects systematically underestimated the subjective effects at around 7 minutes compared with the peak of the experience, and erroneously declared a return to baseline in spite of still significant subjective and neurophysiological effects; however, the measured EEG power spectra appear to be incompatible with this possibility.

We observed more salient divergences with the previous report by Timmermann and colleagues at other frequency bands. The power of delta (1 – 4 Hz) oscillations increased compared with the eyes-closed baseline, while this increase only appeared as a trend in the report by Timmermann and colleagues. However, our results are consistent with an EEG study of the effects of ayahuasca, which found that delta power increases correlated with DMT plasma concentration, but did not correlate with the concentration of several psychoactive beta-carbolines also found in the brew (harmine, harmol, harmaline, harmalol and tetrahydroharmine) [7]. Importantly, an independent EEG study of ayahuasca found small decreases in delta power that vanished at 120 min after ingestion, which coincides with the peak DMT plasma concentration [4]. Psilocybin was found to increase lagged phase synchronization of delta oscillations [84], and hypersynchronous delta activity has been reported in rodents after administration of DMT [85] and 5-MeO-DMT [86], a close structural analogue of DMT [43]; however, LSD decreased delta power in humans [10]. This heterogeneity could be in part explained by the different neurochemical profile of these drugs [76], especially by activity at other serotonin receptor subtypes (e.g. 5-HT1A, 5-HT1B) as suggested by 5-MeO-DMT-increased delta power in 5-HT2A knockout mice [86]. Also in contrast with the results reported by Timmermann and colleagues, we did not find that DMT increased power in the theta band, in agreement with other studies of ayahuasca, psilocybin and LSD. This discrepancy, however, could be caused by assessments of different contributions (oscillatory vs. fractal components) to the theta power [11].

Perhaps our most salient result consists of increased gamma power under DMT, correlating with multiple items from the 5D-ASC, NDE and MEQ-30 scales that reflect aspects of mystical-type experiences. Gamma power increases did not correlate with the number of discarded components/electrodes/channels, and were preserved after conservative EEG processing criteria which led us to discard 6 out of 35 participants. The role played by gamma oscillations in the neurobiology of psychedelic experiences remains unclear, mainly because gamma activity can result from muscle tension, jaw clenching and microsaccades [87]. In contrast to the results reported by Timmermann et al. intravenous DMT, an early EEG field study of ayahuasca found hyper-coherence in the gamma band [38], consistent with the results from Schenberg and colleagues. However, we note that Timmermann et al. observed differences in the gamma band comparing baseline vs. DMT, but not when comparing placebo vs. DMT. In a study with 50 healthy participants, Kometer et al. found that psilocybin administration results in increased high frequency (55 – 100 Hz) oscillations within the high gamma range [84] that correlated with the reported intensity of mystical experiences, also in line with a preliminary report that also found increased gamma global synchrony [88]. MEG recordings acquired during the acute effects of LSD and psilocybin systematically failed to find gamma power increases compared with placebo [5, 10]. Invasive recordings performed in animals support that psychedelic-induced gamma increases are at least partly mediated by 5-HT2A activation [89]. While past discussions on these discrepancies have focused on the possibility of EEG confounds within the gamma range, we believe that at least some of these discrepancies could also be attributed to differences in contextual factors. Variables related to set and setting could facilitate certain kinds of experiences whose neural correlates lie in the gamma range; moreover, anxious states may result in tension and movement, confounding activity in this band.

One of the most interesting characteristics of the psychedelic drugs is their capacity to induce peak experiences of unity and transcendence, combined with feelings of sacredness, deep meaning, positive mood, ineffability and paradoxicality [30, 31, 63]. These mystical-type experiences correlate with positive outcomes in therapeutic applications of psilocybin, occur with dose-dependent frequency, and are usually placed by research participants among the most meaningful experiences of their lives, even decades after the event [31, 90–92]. A possible neurophysiological mechanism underlying these experiences is increased local and long-range synchrony of gamma oscillations. Supporting this possibility, multiple studies have shown that states achieved by long-term meditators following certain traditions (e.g. non-dual awareness) [93–95] share several defining features with the phenomenology of psychedelic-induced mystical-type experiences [96]. It has also been proposed that surge of gamma band coherence near death is a correlate of NDE [97], an altered state of consciousness that has been compared with the DMT experience in terms of subjective experience [55–57]. In spite of their obvious relevance, very little is known about the neurobiological underpinnings of psychedelic-induced mystical-type experiences and is difficult to know to what extent contextual priming and framing plays a role in these experiences. Field studies seem especially apt to investigate the neurobiological basis of ‘mystical-type’, ‘peak’, or ‘unitive’ experiences, especially in the case of participants who approach psychedelic use from a spiritual perspective. We established gamma increases as a correlate of several 5D-ASC, NDE and MEQ-30 items related to the phenomenology of mystical experiences. As shown in Fig. 5, these correlations tended to manifest most strongly near the peak of the experience (3 min) and then receded gradually. Previous DMT research did not find correlations between gamma band oscillations and these items [56]; however, this work assessed subjective experience using visual analogue scales (VAS) which might not be comparable with the results of well-validated psychometric questionnaires.

We replicated previous findings of increased signal diversity (as measured using the Lempel-Ziv algorithm) under the acute effects of serotonergic psychedelics, including DMT [8, 56]. We also demonstrated that the collective properties of EEG oscillations differ under DMT in comparison to the baseline condition: alpha oscillations decreased coherence and metastability, while gamma oscillations showed the opposite behaviour. As hypothesized previously by Stuckey and colleagues [38], and as supported by the discussion in the previous paragraph, gamma hyper-synchrony could be a manifestation of increased information binding underlying psychedelic-induced unitive experiences. Recently, we found increased low gamma band coherence and signal diversity in the EEG of expert meditators belonging to multiple different traditions [61]. These results are also consistent with a potential involvement of gamma oscillations in certain aspects of the psychedelic-experience that are both facilitated by natural settings and common to other non-pharmacological altered states of consciousness.

Doesn't seem like overall activity decreased a lot. Interesting read
https://www.biorxiv.org/content/10.1101 ... 145v1.full

[Astra052]

While we replicated previous findings concerning decreased power in the alpha band [4–11], including work showing that this depends on 5-HT2A receptor stimulation [9], some discrepancies appeared in the time course of alpha power changes after DMT inhalation in the present study. Reduced alpha power manifested most strongly immediately after DMT administration, and gradually receded towards baseline values after approximately 7 minutes. In contrast, previous work by Timmermann and colleagues reported that reports of subjective effect intensity were reduced to half of their peak value after 7 minutes and that alpha rhythm amplitude did not completely recover until approximately 15 minutes after the injection of doses ranging between 7 mg and 20 mg DMT fumarate [11]. These differences in the time course of alpha power reductions could be attributed to different pharmacokinetics between inhaled and intravenous administration routes, with some reports suggesting an equally rapid onset but shorter duration in the case of inhaled DMT [64]. Another possibility is that the effective dose in our study was lower than the doses employed by Timmermann and colleagues. Even though we did not quantify DMT content in the smoked samples, participants and facilitators declared a typical dose of 40 mg, in all cases extracted from Mimosa hostilis bark following a standard acid-base extraction procedure [81]. Previous analysis of similar DMT samples showed an average purity of 85% [82], which would imply an average dose of 35 mg in our study, comparable to the maximum dose used in Timmermann, et al. (2019) when one considers brain availability from an inhaled dose vs. intravenous administration. While smoked and intravenous DMT are both more potent than intramuscular injections [83], more research is required to establish a more precise correspondence between these two routes of administrations. A third possibility is that subjects systematically underestimated the subjective effects at around 7 minutes compared with the peak of the experience, and erroneously declared a return to baseline in spite of still significant subjective and neurophysiological effects; however, the measured EEG power spectra appear to be incompatible with this possibility.

We observed more salient divergences with the previous report by Timmermann and colleagues at other frequency bands. The power of delta (1 – 4 Hz) oscillations increased compared with the eyes-closed baseline, while this increase only appeared as a trend in the report by Timmermann and colleagues. However, our results are consistent with an EEG study of the effects of ayahuasca, which found that delta power increases correlated with DMT plasma concentration, but did not correlate with the concentration of several psychoactive beta-carbolines also found in the brew (harmine, harmol, harmaline, harmalol and tetrahydroharmine) [7]. Importantly, an independent EEG study of ayahuasca found small decreases in delta power that vanished at 120 min after ingestion, which coincides with the peak DMT plasma concentration [4]. Psilocybin was found to increase lagged phase synchronization of delta oscillations [84], and hypersynchronous delta activity has been reported in rodents after administration of DMT [85] and 5-MeO-DMT [86], a close structural analogue of DMT [43]; however, LSD decreased delta power in humans [10]. This heterogeneity could be in part explained by the different neurochemical profile of these drugs [76], especially by activity at other serotonin receptor subtypes (e.g. 5-HT1A, 5-HT1B) as suggested by 5-MeO-DMT-increased delta power in 5-HT2A knockout mice [86]. Also in contrast with the results reported by Timmermann and colleagues, we did not find that DMT increased power in the theta band, in agreement with other studies of ayahuasca, psilocybin and LSD. This discrepancy, however, could be caused by assessments of different contributions (oscillatory vs. fractal components) to the theta power [11].

Perhaps our most salient result consists of increased gamma power under DMT, correlating with multiple items from the 5D-ASC, NDE and MEQ-30 scales that reflect aspects of mystical-type experiences. Gamma power increases did not correlate with the number of discarded components/electrodes/channels, and were preserved after conservative EEG processing criteria which led us to discard 6 out of 35 participants. The role played by gamma oscillations in the neurobiology of psychedelic experiences remains unclear, mainly because gamma activity can result from muscle tension, jaw clenching and microsaccades [87]. In contrast to the results reported by Timmermann et al. intravenous DMT, an early EEG field study of ayahuasca found hyper-coherence in the gamma band [38], consistent with the results from Schenberg and colleagues. However, we note that Timmermann et al. observed differences in the gamma band comparing baseline vs. DMT, but not when comparing placebo vs. DMT. In a study with 50 healthy participants, Kometer et al. found that psilocybin administration results in increased high frequency (55 – 100 Hz) oscillations within the high gamma range [84] that correlated with the reported intensity of mystical experiences, also in line with a preliminary report that also found increased gamma global synchrony [88]. MEG recordings acquired during the acute effects of LSD and psilocybin systematically failed to find gamma power increases compared with placebo [5, 10]. Invasive recordings performed in animals support that psychedelic-induced gamma increases are at least partly mediated by 5-HT2A activation [89]. While past discussions on these discrepancies have focused on the possibility of EEG confounds within the gamma range, we believe that at least some of these discrepancies could also be attributed to differences in contextual factors. Variables related to set and setting could facilitate certain kinds of experiences whose neural correlates lie in the gamma range; moreover, anxious states may result in tension and movement, confounding activity in this band.

One of the most interesting characteristics of the psychedelic drugs is their capacity to induce peak experiences of unity and transcendence, combined with feelings of sacredness, deep meaning, positive mood, ineffability and paradoxicality [30, 31, 63]. These mystical-type experiences correlate with positive outcomes in therapeutic applications of psilocybin, occur with dose-dependent frequency, and are usually placed by research participants among the most meaningful experiences of their lives, even decades after the event [31, 90–92]. A possible neurophysiological mechanism underlying these experiences is increased local and long-range synchrony of gamma oscillations. Supporting this possibility, multiple studies have shown that states achieved by long-term meditators following certain traditions (e.g. non-dual awareness) [93–95] share several defining features with the phenomenology of psychedelic-induced mystical-type experiences [96]. It has also been proposed that surge of gamma band coherence near death is a correlate of NDE [97], an altered state of consciousness that has been compared with the DMT experience in terms of subjective experience [55–57]. In spite of their obvious relevance, very little is known about the neurobiological underpinnings of psychedelic-induced mystical-type experiences and is difficult to know to what extent contextual priming and framing plays a role in these experiences. Field studies seem especially apt to investigate the neurobiological basis of ‘mystical-type’, ‘peak’, or ‘unitive’ experiences, especially in the case of participants who approach psychedelic use from a spiritual perspective. We established gamma increases as a correlate of several 5D-ASC, NDE and MEQ-30 items related to the phenomenology of mystical experiences. As shown in Fig. 5, these correlations tended to manifest most strongly near the peak of the experience (3 min) and then receded gradually. Previous DMT research did not find correlations between gamma band oscillations and these items [56]; however, this work assessed subjective experience using visual analogue scales (VAS) which might not be comparable with the results of well-validated psychometric questionnaires.

We replicated previous findings of increased signal diversity (as measured using the Lempel-Ziv algorithm) under the acute effects of serotonergic psychedelics, including DMT [8, 56]. We also demonstrated that the collective properties of EEG oscillations differ under DMT in comparison to the baseline condition: alpha oscillations decreased coherence and metastability, while gamma oscillations showed the opposite behaviour. As hypothesized previously by Stuckey and colleagues [38], and as supported by the discussion in the previous paragraph, gamma hyper-synchrony could be a manifestation of increased information binding underlying psychedelic-induced unitive experiences. Recently, we found increased low gamma band coherence and signal diversity in the EEG of expert meditators belonging to multiple different traditions [61]. These results are also consistent with a potential involvement of gamma oscillations in certain aspects of the psychedelic-experience that are both facilitated by natural settings and common to other non-pharmacological altered states of consciousness.

Doesn't seem like overall activity decreased a lot. Interesting read
https://www.biorxiv.org/content/10.1101 ... 145v1.full

I don't think Kastrup necessarily cares by how much the activity went down but that going down at all correlated with a "heightened" experience. Jill Bolte Taylor's stroke story sort of relates to this I think.

[Jim Cross]

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

I think the questions raised in this thread are relating more to science than metaphysics and your response with others is more about metaphysics.

It is possible to discuss science from an idealistic perspective without using metaphysics as a cudgel against science as can be shown from this article in SciAm by Bernardo himself.

https://blogs.scientificamerican.com/ob ... -research/

The general problem I have with Bernardo's view on brain activity can be shown from this quote from the article:

Finally, to suggest that brain activity randomness explains psychedelic experiences seems inconsistent with the fact that these experiences can be highly structured and meaningful—often even the most meaningful in life.

In short, a formidable chasm still yawns between the extraordinary richness of psychedelic experiences and the modest alterations in brain activity patterns so far observed.

The problem is the conflation of structured, meaningful, and richness with awareness itself. That the mind can structure chaotic experience into something meaningful is well known. Presented with a random pattern of dots, or ink blots on paper, many people can spot an image. Our brain is continually attempting to comprehend the world and a chaotic experience, such as that provided by psychedelics, can generate a compensatory response of simplification that is highly meaningful to one undergoing the experience. This by itself says nothing about awareness itself which, in fact, may actually be reduced because significant aspects of the experience - the ones that don't fit the narrative - are dropped from experience in favor of the "meaningful" ones that do fit the narrative.

[Astra052]

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

I think the questions raised in this thread are relating more to science than metaphysics and your response with others is more about metaphysics.

It is possible to discuss science from an idealistic perspective without using metaphysics as a cudgel against science as can be shown from this article in SciAm by Bernardo himself.

https://blogs.scientificamerican.com/ob ... -research/

The general problem I have with Bernardo's view on brain activity can be shown from this quote from the article:

Finally, to suggest that brain activity randomness explains psychedelic experiences seems inconsistent with the fact that these experiences can be highly structured and meaningful—often even the most meaningful in life.

In short, a formidable chasm still yawns between the extraordinary richness of psychedelic experiences and the modest alterations in brain activity patterns so far observed.

The problem is the conflation of structured, meaningful, and richness with awareness itself. That the mind can structure chaotic experience into something meaningful is well known. Presented with a random pattern of dots, or ink blots on paper, many people can spot an image. Our brain is continually attempting to comprehend the world and a chaotic experience, such as that provided by psychedelics, can generate a compensatory response of simplification that is highly meaningful to one undergoing the experience. This by itself says nothing about awareness itself which, in fact, may actually be reduced because significant aspects of the experience - the ones that don't fit the narrative - are dropped from experience in favor of the "meaningful" ones that do fit the narrative.

You're conflating a chaotic experience with a chaotic brain state here. You could present a jumbled mess of something and I could percieve it as an image while my brain is completely fine meanwhile my brain could be in a jumbled state and I'd probably be in a state similar to anesthesia. I don't think what you're saying is necessarily wrong, it should just be kept in mind that seeing something chaotic isn't the same as your brain going nuts, which is what BK is talking about.

[Jim Cross]

You're conflating a chaotic experience with a chaotic brain state here. You could present a jumbled mess of something and I could percieve it as an image while my brain is completely fine meanwhile my brain could be in a jumbled state and I'd probably be in a state similar to anesthesia. I don't think what you're saying is necessarily wrong, it should just be kept in mind that seeing something chaotic isn't the same as your brain going nuts, which is what BK is talking about.

I'm really not sure what your point is. Are you saying you can have a chaotic brain state without a chaotic experience or what? Have you ever experienced psychedelics? The early parts of the experience are usually very chaotic with much of it unable to be assimilated. These parts are frequently not even remembered as the "meaningful" parts start to occupy your memory of the experience. I am speaking here of relatively intense experiences, not light doses which are usually more like eye candy.

[Jim Cross]

When these feelings erupt within an ayahuasca session, they can manifest as overwhelming sensations and emotions that seem unrelated to any known circumstance. Arising in disconnected, incoherent form, they’re unaccompanied by any sense of meaning. The chaotic nature of certain difficult ayahuasca experiences can lead to overwhelming sensations, incomprehensible surges of powerful emotions like terror, grief, or despair. Correspondingly these emotions parallel the overwhelming feelings a small child might experience in trauma.

Dr. Gabor Maté said some intriguing things at a Psychedelic Science 2017 workshop on ayahuasca. “There’s no such thing as a bad trip on ayahuasca,” Maté believes. “People say, ‘I felt fear, terror, rage, confusion such as I never felt before.’ ‘Yes, you have,’ I say. ‘You just don’t recall it.’”

He suggested that what we call a “bad trip” could be a reactivation of early childhood trauma. These can be overwhelming experiences, infant or even prenatal. They are encoded not in the brain’s centers of cognitive memory (these don’t develop fully until 18–24 months of age) but directly into the body.

https://psychedelic.support/resources/w ... ayahuasca/

The comparison to the experience of an infant hadn't occurred to me before. But in case of the adult on psychedelics and the infant there is commonality of trying to make sense of overwhelming and chaotic experience.

The article BTW is pretty good at calling out that the road to transformative experience frequently follows a difficult path.

[Astra052]

You're conflating a chaotic experience with a chaotic brain state here. You could present a jumbled mess of something and I could percieve it as an image while my brain is completely fine meanwhile my brain could be in a jumbled state and I'd probably be in a state similar to anesthesia. I don't think what you're saying is necessarily wrong, it should just be kept in mind that seeing something chaotic isn't the same as your brain going nuts, which is what BK is talking about.

I'm really not sure what your point is. Are you saying you can have a chaotic brain state without a chaotic experience or what? Have you ever experienced psychedelics? The early parts of the experience are usually very chaotic with much of it unable to be assimilated. These parts are frequently not even remembered as the "meaningful" parts start to occupy your memory of the experience. I am speaking here of relatively intense experiences, not light doses which are usually more like eye candy.

My point is that the "chaotic state" BK talks about is in reference to things seen on EEGs and the like, not the subjective experience of the trip. You can see something chaotic while having a normally functioning brain state.