Sunday, April 30, 2023

There Is No Evidence of a Neural Explanation for Out-of-Body Experiences

When neuroscientists or the mainstream press attempt to suggest natural explanations for near-death experiences or out-of-body experiences, we often get some bad examples of misstatements and inaccuracies. I discussed some of these misstatements and inaccuracies in my post "Misleading Claims in Attempts to Naturally Explain Near-Death Experiences and Out-of-Body Experiences." There was in a recent press article another case of a neuroscientist misspeaking about out-of-body experiences, claiming that neuroscientists have some understanding of what causes them. There is no mention of any new research, just a reference to one of the papers below. I will discuss below some of the main papers cited by neuroscientists claiming some evidence of a neural explanation for out-of-body experiences, and I will explain why they fail to show such a thing. 

But first let me note that neuroscientists speaking on such a topic typically mislead us about the incidence of out-of-body experiences. For example, the neuroscientist mentioned above quotes an estimate that 5% of the population have out-of-body experiences, citing Susan Blackmore. But according to the paper here, "For example, from a selection of 321 individuals on the electoral register, 12% of respondents identified that they had experienced at least one OBE (Blackmore, 1984)." Below is a graph from page 185 of a paper on this topic, the paper "Out-of-Body Experiences" by Carlos S. Alvarado. 

incidence of out-of-body experiences

Surveys of the general public have found 10% having out-of-body experiences; surveys of students have found 25% having out-of-body experiences; and surveys of parapsychology groups have found 48% of the persons reporting out-of-body experiences. 

As another preliminary, let me mention the unreliability of second-hand accounts of unusual experiences.  I may put accounts of unusual experiences in three categories. 
  • Lowest quality: accounts that are entirely second-hand, without including any quotations from the person having the experience, particularly if such accounts are responses to questions not quoted, which may have been leading questions. 
  • Medium-low quality: accounts that are second-hand, but include fragmentary quotations of words or phrases used by the person having the experience (with the quality being low not medium if the answers were responses to leading questions). 
  • High quality: accounts consisting of paragraphs or contiguous sentences stated by an observer,  which were not responses to leading questions.  

Here is an imaginary example of some very low-quality evidence, one in which we have a leading question in the middle:

Dr. Fictional: Here try on these special "wrong prescription" glasses that are for people three times more nearsighted than you.

Miss Hypothetical: Oh my goodness! My perception is all scrambled! 

Dr. Fictional: So is it kind of like you're out of your body?

Miss Hypothetical: Well, hmm, I guess you might say it's a bit like being out of my body.

Dr. Fictional: Okay, I'm recording you said it was "like being out of my body." 

Below are some of the main papers cited by neuroscientists claiming a neural explanation for out-of-body experiences.

  • "The Experimental Induction of Out-of-Body Experiences."  This paper has an inaccurate title, as nothing like an like out-of-body experiences was induced. The paper describes some artificial hi-tech setup in which people wearing goggles like virtual reality goggles watch video footage of their body produced by a video camera behind them. Anyone wearing such goggles would know he was experiencing some virtual reality setup, and such an experience would not match those reported by those having out-of-body experiences. The paper does nothing to show any neural explanation for out-of-body experiences. 
  • "Out‐of‐body experience and autoscopy of neurological origin." This 2004 paper cites six cases of people with some kind of neurological problem, usually partial seizures, but in one case migraine headaches. The paper tries to get us to believe that these six people had out-of-body experiences. Problematically, we fail to get any first-hand full-sentence accounts from these people consisting of quotes that are one or more sentences long. The accounts are second-hand accounts of their experiences, made by the paper authors, who may have been motivated to make the accounts sound like out-of-body experiences. We get mere sentence fragment quotations from the subjects. In general, second-hand accounts of someone else's unusual psychic experiences are not reliable. Although the authors claim that four of these supposed out-of-body experiences were caused by partial seizures, we have no way of knowing whether that it is correct. We have no way of knowing whether the experiences reported were things that took place during any medical incident such as a seizure. Since out-of-body experiences are extremely common, and since partial seizures are also common (occurring to about 1% of the population), a few reports that might be out-of-body experiences coming from people who sometimes suffer from partial seizures does nothing to show that the partial seizures caused the out-of-body experience. The only reliable way to verify that an out-of-body experience might be caused by partial seizure would be to get something like a video of someone describing an out-of-body experience while they were hooked up to an EEG machine that showed brain waves that characterize a partial seizure. The authors have done no such thing. The authors failed to do anything to show that the supposed out-of-body experiences occurred while the partial seizures occurred. 
  • "Stimulating illusory own-body perceptions." This 2002 paper has some quotes by a subject in whom the authors had brain-zapped with electricity, by inserting electrodes in her brain. The authors have attempted to portray this as evidence of an artificially induced out-of-body experience. But the only sentence that the paper quotes from the subject is one that does not indicate a full out-of-body experience. That sentence is this: "I see myself lying in bed, from above, but I only see my legs and lower trunk." That sounds like some weird electricity-induced perception anomaly that is not properly described as an out-of-body experience. During an out-of-body experience a person will typically report leaving his body and seeing his entire body (not just the legs and lower trunk) from outside of the body. Eager to report some experimental induction of an out-of-body experience, our authors seem to have taken some account that does not match those of out-of-body experiences, and called that an out-of-body experience. The authors make this claim: "Two further stimulations induced the same sensation, which included an instantaneous feeling of 'lightness' and 'floating' about two metres above the bed, close to the ceiling." Since this is not an actual full-sentence quote from the subject, it has very little value as evidence. A second-hand account of a person's weird experience during brain zapping (by some other person who did not have that experience) is pretty worthless as evidence. What would we have read from a transcript of what the subject said, one including any questions the subject was asked? We have no idea. 
  • "The Out-of-Body Experience: Disturbed Self-Processing at the Temporo-Parietal Junction."  The authors of this 2005 paper cause us to lose confidence in their credibility on this topic when they state, "OBEs have been observed predominantly in patients with epilepsy and migraine." This statement is not at all correct. The authors try to justify it by saying this as their next sentence: "Thus, Lippman (1953) reported two migraine patients with OBEs, and Green (1968) reported that 11% of the OBE subjects that participated in her survey suffered from migraine headaches." Any person who seriously studied out-of-body experiences would have found out that surveys report them occurring in significant fractions of the human population, and might realize the folly of trying to justify a claim that out-of-body experiences are caused mainly by migraines or epilepsy by citing a mere two patients having migraines and out-of-body experiences. And anyone writing carefully would have realized the folly of trying to justify a claim that most out-of-body experiences are produced by migraines or epilepsy by citing some person claiming that merely 11% of some group of people having out-of-body experiences had migraines. Trying to claim that out-of-body experiences are largely caused by migraine headaches makes no sense. In a book about near-death experiences and out-of-body experiences (OBEs), Dr. Peter Fenwick states, "A prominent feature of OBEs is that pain is entirely absent." But since migraine headaches are episodes of intense pain, it makes no sense to claim they are the cause of painless out-of-body experiences. The paper presents no original reports or original experimental research, and does nothing substantive to back up a claim that out-of-body experiences are caused by "disturbed self-processing at the tempero-parietal junction." The Figure 3 we see in the paper (a brain image based on scans of only three subjects) will seem very laughable to anyone familiar with the requirements for robust evidence in brain scanning correlation experiments, which is an absolute minimum of 15 subjects per study group and the following of a detailed, careful blinding protocol. In fact, now experts tell us that thousands of subjects are needed for reliable results in brain scan studies trying to establish correlations. Scientists have no understanding of how a sense of self could possibly arise from neural activity,  so anyone talking about a "disturbed self-processing at the tempero-parietal junction" is simply engaging in empty jargon-decorated hand waving. 
  •  "Voluntary out-of-body experience: an fMRI study." This 2014 paper documents an fMRI brain scan of a woman who claimed to be able to have an out-of-body experiences at will.  Nothing unusual is reported in the fMRI results.  We have one of those brain scan visuals that show particular parts of the brain in bright colors. But this means nothing, because it is well known that innumerable neuroscientists show such visuals when they do fMRI scans showing only differences of only about 1 part in 200 or 1 part in 500. The authors report no brain pathology in the individual, and don't report getting anything that they don't see from a typical brain scan.  
  • "Mind’s Eye: a Case of Out-of-Body Experiences": We have a case report of a woman claiming 3 out-of-body experiences in the past six months during nighttime awakenings. She gives this account: “I see myself as if I was from an airplane and looking down at a distance of about five feet. I feel split and I see myself down. I have my body down, I’m not in my body, I’m out of my body. My mind sees my body, I see the shape of my body. The part of mine that is over…it seems strange to me looks like an angel, an entity. I see the body there but I’m like air…”.  The authors refer to these accounts as "hallucinatory experiences," but do nothing to back up such claims. Their explanation is a feeble one. They state, "The interesting aspect of this case report is the occurrence of OBEs, likely triggered by the frequent night awakenings." There is no reason why waking up at night would cause someone to have an experience of being out of their body.  The authors offer nothing but a little speculative jargon as an explanation, stating this: "It is possible that this situation could facilitate hallucinatory experiences of self as a result of two components: (1) insufficient neurofunctional integration and lack of binding information from different neural networks responsible for the perception of one’s own body as an integral part of psychophysical self-awareness, and (2) the instability of psychophysiological arousal with rebound both on the maintenance of sleep and mental activity."  Such a statement is merely empty hand-waving. They fail to offer any evidence of any pathology or unusual brain state that could explain the reported out-of-body experiences. 
  • "Altered neural dynamics in people who report spontaneous out of body experiences."  This 2019 study got 551 paper to fill in a questionnaire about out-of-body experiences, and found that 24% of them reported at least one out-of-body experience. The authors got EEG readings from 19 people who claimed to have an out-of-body experience, and 21 people who did not make such a claim. The paper provides no good evidence of any different neural dynamics in the subjects who had an out-of-body experience, and its title is inaccurate. Referring to some tiny difference involving less than a second, the authors claim "amplitude of the visual P1 ERP deflection and consistency of alpha-band phase locking were significantly reduced in the participants who had had an OBE," but that "we did not find any group differences in resting state power or in visually induced gamma oscillations. "  The reported difference is a minuscule difference that anyone could have found when comparing brain waves between any two random groups of twenty subjects, and trying to find some difference between them. Look at Figure 2 of the paper, which shows the supposed differences. It shows two little one-second blips (one from the OBE group, the other from the control group), and the blips are almost exactly the same shape. The authors should have been ashamed to have passed that off as evidence of "altered neural dynamics." Ditto for figures 3, 4 and 5. No study like this should be taken seriously unless (1) is a pre-registered stating some specific hypothesis to be tested; and (2) is a study that follows a rigorous blinding protocol, so that people analyzing the EEG waves do not know from which group a particular set of waves comes from.  This study was not a pre-registered study, and did not follow any blinding protocol. No robust evidence has been found of brain differences between the two groups.   
  • "Astral Projection: A Strange Out-of-Body Experience in Dissociative Disorder." We have here a 2021 paper mentioning a report by a teenager of an out-of-body experience. The paper provides no evidence of any brain pathology. We read that "his medical history was negative for symptoms of epilepsy, migraine, syncope, cerebrovascular accident, neurological deficit." We read that "Electroencephalography (EEG) did not reveal any abnormality," and that a "CT scan of the brain did not show any pathological findings." The teenager was from a troubled family, having no mother and a harsh father, and had run away from home several times. Apparently based on his report of having had an out-of-body experience, some psychiatrist labeled the teenager as having "dissociative identity disorder and dissociative fugue." Excluding a vague one-sentence reference to the patient "assuming the identity" of some 18-year-old electrician (which may or may not be a reference to a mere lie by a runaway), no evidence is given for this diagnosis other than the teenager's report of a very  common psychic experience: an out-of-body experience. A test indicated "no psychotic features." No evidence has been provided for any neural or psychological cause for the reported out-of-body experience. The paper provides no clear and sound-seeming evidence to back up the claim that the teenager had "dissociative identity disorder."
  • "Neurophenomenology of Out-of-Body ExperiencesI Induced by Hypnotic Suggestions." In this study 15 people were either asked to imagine having an out-of-body experience, or were hypnotized and told they were having an out-of-body experience. EEG readings were taken of the subject's brain waves while this occurred, but the study reports a "lack of significant EEG differences" between the subjects that were hypnotized and not-hypnotized. Since no convincing evidence is given that any of these people actually had an out-of-body experience, and since no comparison was made between the EEG readings and those of control subjects, no evidence is actually provided of a "neurophenomology of out-of-body experiences." The authors have done nothing to back up their claim that "our results show that OBEs can be easily inducible in hypnosis." It is well-known that people are extremely suggestible under hypnosis, so mere OBE claims of hypnotized subjects told to have an out-of-body experience is no evidence that such experiences occurred to such persons. 
  • "Out-of-body experience, heautoscopy, and autoscopic hallucination of neurological originImplications for neurocognitive mechanisms of corporealawareness and self consciousness."  This is a review article case that has a graph (Figure 3B) trying to give you the impression that large fractions of people experiencing out-of-body experiences have brain lesions. The graph is misleading, and the vast majority of people having out-of-body experiences have no such lesions. The graph was made using 11 cases of out-of-body experiences that the authors have cherry-picked, presumably with an interest in finding people with brain lesions who reported out-of-body experiences. This is cherry-picking, because there are many thousands of documented cases of out-of-body experiences reported by people without brain lesions.  
  • "Visualizing Out-of-Body Experience in the Brain." The authors claim that they produced an out-of-body experience by zapping someone's brain with electrodes that had been implanted in his brain to treat tinnitus. The claim is not well-established, as the authors have not provided any quotes from the subject which sound like something someone would say when having an out-of-body experience. The authors state, "His perception of disembodiment always involved a location about 50 cm behind his body and off to the left."  50 centimeters is about 19 inches, about an arm's length. In out-of-body experiences, people don't report being an arm's length behind their body, but typically report seeing their body from meters above it, often reporting a viewpoint of being on the ceiling. Since the perceptual experience of this paper's subject was produced through brain zapping of a type not done to people having out-of-body experiences, and since we have no testimony from the subject matching that of typical out-of-body experiences, the paper does nothing to help show a neural basis for out-of-body experiences. 
  • "Linking Out-of-Body Experience and Self Processing to Mental Own-Body Imagery at the Temporoparietal Junction."  We hear that eleven subjects "were asked to make right–left judgments about a schematic human figure after having imagined themselves to be in the body position of the figure and to have its visuospatial perspective."  We have the most absurd assertion that the "volunteers’ transformation of their own bodies into the body position of the front-facing figures (as compared with the back-facing figures) mentally simulates the body position and the visuospatial perspective that is experienced during OBEs." No, the weird little exercise described did not do anything to simulate what is experienced during out-of-body experiences. The brain state analytics that follow in the paper are irrelevant, because whatever imagination was occurring in the subjects does not watch the mental experiences of people having out-of-body experiences. 
  • "Out of body experiences and their neural basis."  This article presents no original research, and fails to discuss any good evidence for a neural basis for such experiences. The author says "out of body experiences occur in about 10% of the population," and then claims "the importance of vestibular and multisensory mechanisms in out of body experiences was underlined by their occurrence in several patients with such experiences," apparently failing to see the absurdity of trying to explain something occurring to many millions of people by claiming that "several" of such people had some "vestibular" issue (which is like trying to show that space travel is the cause of heart disease by mentioning that "several" astronauts had heart disease). Then we have a reference to the faulty "Out‐of‐body experience and autoscopy of neurological origin" discussed above. 
  • "The body unbound: Vestibular–motor hallucinations and out-of-body experiences":  This study merely consisted of gathering and analyzing questionnaire data. The authors then do some elaborate statistical rigmarole (including "a series of stepwise multiple regression analyses") designed to show their data is compatible with speculations about neural causes for out-of-body experiences. Since the study is not a pre-registered study, and did not follow any blinding protocol, it seems yet another case of the extremely wide phenomenon of scientists playing "make up your procedure as you go along" and "keep torturing the data until it confesses." The authors knew nothing about the brain states of the people who answered their questions.  They mainly just claim "consistency" with speculation of other scientists, rather than supporting evidence. 
  • "Out-of-Body Experiences in Schizophrenia: A Questionnaire Study." This survey study found "when the OBEs are distinguished on the basis of the descriptions given, into typical OBEs, in which the person seems to leave the body, and pseudo-OBEs, which include all sorts of other experiences, then...it seems that the schizophrenics do not have significantly more OBEs than do control subjects and that having OBEs is not related to either perceptual distortions or to the symptoms of schizophrenia."
  • "Cognitive correlates of the spontaneous out-of-body experience (OBE) in the psychologically normal population: Evidence for an increased role of temporal-lobe instability, body-distortion processing, and impairments in own-body transformations. This was a survey study that asked students about whether they had ever had an out-an-body experience, and also asked questions designed to elicit evidence that the users might be hallucination-prone or have some brain problem. Subjects were given a CAPS survey that can supposedly find evidence of "temporal love instability." The authors claim to have found that those reporting out-of-body experiences scored higher on this CAPS survey than control subjects having no out-of-body experiences, and higher on an LHSH survey designed to find evidence of hallucinations. Unfortunately in section 3.3 we learn that the number of surveyed subjects having real out-of-body experiences was a mere 6. First we are told that "of the 63 participants who took part in this study, 17 of these (26%) claimed to have experienced at least one OBE at some point in their life," but then we are told "Of the OBE group, only six (35%) reported seeing their own body or some form of body representation of the physical self during the OBE, with all the others reporting only the shift in perspective (either visually, as a bodily sensation, or both)." Is six subjects an adequate sample size from which to be judging a greater tendency of any sort? Certainly not. If the authors had done a sample size calculation like good experimental scientists, they would have have found their relevant sample size (six subjects) was way too small to produce any reliable result on a survey of this type; but they failed to do such a calculation. The same shortfall is a problem that occurs in a very large fraction of all neuroscience and psychology studies. Because a way-too-small study group size was used (only six subjects), the authors have not provided any reliable evidence of anything.  
  • "Out-of-Body Experiences, Dreams, and REM Sleep." The authors "tested an explanatory model of OBEs as a form of dreaming." Their Study 1 is irrelevant, involving only a tiny sample set from five people. Their Study 2 analyzed questionnaires from 604 subjects, 136 were readers of a newsletter about lucid dreaming research. After statistical fiddling involving multiple regression, the authors report "Subjects in the current study who reported lucid dreams were 158% more likely to report OBEs than subjects who did not report lucid dreams." But since their subject pool had so many people interested in lucid dreaming (those 136 people who were readers of a newsletter on the subject), we did not have a random sample of the public from which anything can be reliably deduced. And what question was asked to judge whether someone had an out-of-body experience? We don't know, because the authors didn't tell us, and didn't publish their questionnaire. As a result, we can't tell whether this research showed anything. The idea that out-of-body experiences can be explained as dreaming is not credible, and cannot explain the most prominent examples of such experiences, occurring during close brushes with death when people are not dreaming.  
  • "A putative implication for fronto-parietal connectivity in out-of-body experiences."  We have a study in which some task is given to both people who had an out-of-body experience and those who did not. But the number of subjects who did this task and are claimed as having an out-of-body experience is only eleven subjects,  too small a study group size for any kind of reliable result. The study lists the reports of these eleven people, and several of the reports should have been excluded because their accounts don't sound like typical out-of-body experiences (with no reported perception of the body from outside of the body). But the authors have failed to exclude these subjects from their pool of 11 people supposedly reporting out-of-body experiences. The data gathered from this poorly-designed study does nothing to justify the weak claim of its authors that their data "suggests that OBEs might be mediated by a functional disconnection of information between the PFC and the TPJ." The authors have presented no good evidence that "fronto-parietal connectivity" has anything to do with out-of-body experiences. The authors were looking for some performance difference in some weird task they devised, but do not report any convincing evidence of such a difference (data-dredging their way to some little difference somewhere of only p < .03, which is very unimpressive with a study group size this small). 
  • "Out-of-body experiences associated with seizures." The paper does not attempt to suggest seizures are an explanation for out-of-body experiences (which almost all occur in people who do not have epilepsy). The paper finds reports of previous out-of-body experiences in 7 out of 100 people having seizures.  We read, "The finding that 6 of the 7 patients who reported out-of-body experiences associated with seizures described them as occurring only once or twice many years ago raises the question of whether those experiences were truly seizure-related."
  • "Surge of neurophysiological coupling and connectivity of gamma oscillations in the dying human brain." Here we have another misleading use of the word "surge" in a science paper headline, a paper co-authored by one of the researchers (Jimo Borjigin) who authored the equally mistitled rat study "Surge of neurophysiological coherence and connectivity in the dying brain."  The paper merely describes a little brain activity in two people after a respirator was turned off, with no evidence of brain activity continuing for more than a few seconds after the heart has stopped. The lines on brain waves charts go up and down, and there are seven or so channels of brain waves (including a gamma channel); so at any second you can usually find some little line going up and call that a "surge," although at the same time other lines (representing other brain wave channels) will probably be going down. Using the term "surge" in the title of the paper was misleading, rather like  tracking the price of Microsoft, seeing it go up 2% at 2:00, and calling that a surge. The authors of the study did not even report a surge in gamma waves, one of the brain wave channels. Eager to get something they could call a surge, the authors got their little "surge" after some statistical fiddling with the signals, to get some statistical measure that only shows up after arbitrary analytics. Almost any random ten seconds of brain wave activity can be statistically analyzed to show a little "surge" somewhere, if you're willing to dredge up secondary statistical measures. Keep torturing the data, and it will confess as you wish.  Shamefully, the journal Science has an article on this paper with the misleading headline "Burst of brain activity during dying could explain life passing before your eyes"; and the Smithsonian site has an equally misleading click-bait headline of "Surging Brain Activity in Dying People May Be a Sign of Near-Death Experiences." There is no evidence that either of these two people had an experience of "life passing before their eyes" or anything like near-death experiences. The subjects were unconscious when the respirator was turned off, and there is no evidence of any consciousness. Unconscious people have gamma wave activity (the activity reported), and you have plenty of gamma activity while you are sleeping. No "neural correlates of the NDE" were reported by the paper. As two MDs point out in a commentary on this paper, "The researchers reported no evidence whatsoever that these brain activities were correlated with conscious experiences in those two patients—and no reason to compare these results with prospective NDE studies in patients who have survived a cardiac arrest."  To get the real truth of what was happening here, you need to open up the supplemental information document of the paper. The visuals in that document show the brain waves of the patients all dying off to become a flat line by the time the hearts of the patients stopped.  As I explain in my post here, such visuals contradict claims that the paper does anything to support a neural explanation for near-death experiences.  In that post I discuss some misleading or totally unwarranted claims made by one of the authors of this paper. 
  • "Causal evidence for the processing of bodily self in the anterior precuneus." An NPR story has a bogus headline about this study: "Having an out-of-body experience? Blame this sausage-shaped piece of your brain." The study involves people who had some region of their brain called the anterior precuneus zapped by electrodes implanted in their brains. But the abstract of the paywalled study does not mention any out-of-body experiences produced by such artificial manipulations, so the NPR headline is unwarranted. And no such study could ever explain out-of-body experiences arising in people who do not have electrodes implanted inside their brains.  See my post "This Brain-Zapping Bungled Mess Sheds No Light on Out-of-Body Experiences" here for a detailed discussion of the flaws of this study.  The main flaw is that the experimenters repeatedly asked "leading" questions of people who were having their brain zapped, questions that seemed designed to get from them some quote sounding a little like an out-of-body experience, questions such as, "Did you feel any floating?" In a proper study of this type, subjects would only be asked neutral questions such as "tell me how that feels," or maybe "can you tell me more about that" after a subject had given some description. After reviewing all of the observer responses stored in a spreadsheet available with the original paper, I wrote " None of the patients reported anything that can be accurately described as an out-of-body experience." I also list in that post four cases in which the paper authors inaccurately described what their subjects reported. 
  • "Out-of-Body Experiences and Hallucinatory Experiences: A Psychological Approach." This study involved having hundreds of students fill out questionnaires. One question was used to judge whether the subjects had ever had an out-of-body experience, and other questions were used to produce scores rating some nebulous concepts such as "fantasy proneness" and "schizotypy" (the latter a notoriously slippery psychological term). The authors claim psychological differences in those having out-of-body experiences. Unfortunately the study is invalid because it failed to use a proper question to judge whether the subjects had ever had an out-of-body question. Asking a question that might have been answered "yes" by anyone having a vivid dream or a vivid travel recollection or a vivid star-gazing experience, the question used was, "Have you ever had an experience in which you felt that 'you' were located 'outside of' or 'away from' your physical body, that is, the feeling that your consciousness, mind or awareness was at a different place from your physical body?" A proper question asking about out-of-body experiences would have asked whether the person had perceived his body from a position outside of his body or had an experience of leaving his body. The authors have not done anything to show any neural basis for out-of-body experiences. Contrary to the insinuations of such a paper, we read the following in another paper:
"Measures of traits and symptoms related to psychosis have failed to differentiate OB [out-of-body] experients from nonexperients (Gabbard & Twemlow, 1984; Irwin, 1980; McCreery & Claridge, 1995). McCreery (1993) found no relationship between the occurrence of OBEs and his participants’ psychiatric histories. Gabbard and Twemlow (1984) concluded that 'the OBE group was significantly healthier than a variety of other normative groups in the population and did not have the constellation of symptoms often equated with character disorders, such as psychosomatic disorders, alcohol and drug abuse, or stimulus seeking' (p. 32)"

It is rather clear from these examples that the body of neuroscience studies attempting to find evidence of a neural explanation for out-of-body experiences is mainly a swamp of junk science, characterized massively by misleading claims,  empty hand-waving, poor study designs, irrelevancies and questionable research practices. Nowhere in such studies can we find any credible neural explanation of why anyone would ever report seeing their body from a position meters above their body, as we so often hear in reports of out-of-body experiences. Nowhere in such studies do we find evidence that out-of-body experiences are hallucinatory, and one of the studies above suggests such experiences are not reported more often in the main group having hallucinations (schizophrenics). In general the  body of neuroscience studies attempting to find evidence of a neural explanation for out-of-body experiences can be described as hand waving decorated by neuroscience jargon and some weak poorly designed experimentation. When experimentation is involved, it is typically irrelevant or having too few subjects to be evidence for anything. The recent claim by a neuroscientist that scientists are starting to understand a neural cause of out-of-body experiences was one of the very many groundless boasts made by scientists. 

If you were to ask someone two hundred years ago to imagine the strongest evidence he could get that his mind is not produced by his brain, such a person might have answered that it would be observing his body from outside of his body. Out-of-body experiences are one of the strongest types of evidence against claims that the mind is the product of the brain (or the same as the brain).  The failure of neuroscientists to even "get to first base" in credibly explaining such experiences as brain activity is a failure that "speaks volumes" against such claims. 

If the authors of the papers mentioned above were to do a deep and thorough study of reports of out-of-body experiences (which they almost all fail to do), they would discover massive evidence further discrediting their speculations: evidence such as very many reports by people during out-of-body experiences of discovering things they never first learned about through normal sensory experience (see here for examples), and very frequent reports of unprecedented perceptual abilities during such out-of-body experiences.  A very big difference between most such authors and myself is that I have very massively studied books and papers written by those holding a materialist or mainstream viewpoint on the brain (as shown by thousands of links to such papers and books on this site), but most such authors have failed to decently study the massive literature documenting evidence for the paranormal, doing no more than a cursory "sometimes briefly wade their feet in the water" kind of looking at such literature. My approach has been to massively study what is claimed to defy my view about the mind and brain (along with the opposite type of evidence), but few neuroscientists take so balanced an investigative approach. Neuroscientists prefer a "don't rock my own boat" approach of not seriously studying evidence that seems to defy their beliefs about brains. In general we should not regard  people taking such an approach as thorough scholars of human mental phenomena. 

Sunday, April 23, 2023

Exhibit A Suggesting Scientists Have No Understanding of How a Brain Could Imagine Anything

Let us imagine you are a biologist trying to convince someone that the circulation of the blood within a human body can be explained by what we know about the human body.  You could explain that without going outside a discussion of human anatomy. You could explain anatomical and molecular details of the human circulatory system that would back up very well your claim that the circulation of the blood is well-explained by known biology facts. These would include details such as these: 

  • how the human body has a network of arteries capable of distributing throughout the body blood from a pumping heart ;
  • how the human body has a network of veins capable of carrying blood  from parts of the body back to the pumping heart;
  • how the human heart has a physical structure that is just the structure we might expect it to have if it served as a pump to distribute blood throughout the body;
  • how the human heart is regularly witnessed to be undergoing a rhythmic pumping action when the heart is observed by doctors during heart surgery;
  • how scientists have developed instruments that can measure the pressure of blood pumped the heart;
  • how the blood pumped by the heart contains a hemoglobin molecule that has just the right arrangement allowing blood to carry oxygen needed by cells;
  • how the blood of the human body is constantly refreshed with oxygen obtained by the lungs that take in air from outside a person;
  • how anyone can get evidence of their own heart beat simply by placing one hand on their wrist, and feeling the heart beats that typically occur at a rate of about one beat per second.
But let us imagine you are a biologist attempting to convince someone that the brain is the source of the human mind, and that memories are stored in brains. The situation would be completely different. There would be no details of human anatomy that you could cite to support this claim. 

You could not cite the measurement of electrical waves in the brain as proof that the brain produces the human mind, because we know all kinds of things that involve electricity but presumably have nothing to do with mind or memory. For example, lightning storms show very powerful manifestations of electricity, but no one thinks that lightning storms involve any kind of memory or mentality. You could not cite some arrangement of matter in a brain as being evidence that brains produce self-hood or consciousness, because no one knows of any way to arrange matter that would tend to produce self-hood or consciousness; and no device manufactured by humans has any real self-hood or consciousness. 

Speaking honestly, you could not claim that the brain must be computing because it resembles human devices that do computing.  Human computers have characteristics such as silicon chips, operating systems such as Unix or Microsoft Windows, application programs, and information transfer protocols such as ASCII. No such things exist in the human brain. No one has ever found anything in the human brain like an operating system or an application program or a silicon CPU chip. 

Speaking honestly, you could not claim that the brain must be storing memories and retrieving memories because it has anatomical characteristics resembling the physical structure of human devices capable of storing and retrieving information. Such devices have seven things not found in the human brain, as I discuss in my post "The Brain Has Nothing Like 7 Things a Computer Uses to Store and Retrieve Information."  

Speaking honestly, you cannot claim that there is some molecule traveling around in the brain and functioning as an information carrier,  in a way rather like the hemoglobin molecule in blood carries around oxygen. This is because no such molecule has ever been discovered. 

So what do you do if you are a biologist trying to convince people that the brain is the source of the human mind and the storage place of memories? You have no convincing anatomical details you can cite. You are pretty much empty-handed. In such a situation what you will probably do is to mainly fill up your post, article or essay with not very relevant discursions, speculations and digressions, hoping to use enough words to give someone an impression that you have something a little bit like an explanation.  That's what goes on in a recent essay by neuroscientist Andrey Vyshedskiy, one entitled "Imagination makes us human – this unique ability to envision what doesn’t exist has a long evolutionary history."  Vyshedskiy attempts to persuade us that he has some idea of where human imagination comes from, but fails very badly. 

After identifying himself as a neuroscientist who "studies how children acquire imagination," someone "especially interested in the neurological mechanisms of imagination," Vyshedskiy starts his explanation attempt by giving us a section entitled "From bacteria to mammals" which consists of six paragraphs that parrot Darwinist dogmas about the evolution of life on Earth. Nothing he says in the section does anything to explain how humans are able to imagine anything. Below is an example of the utterly irrelevant "just so" stories  Vyshedskiy tells in one of his paragraphs of this section:

"Not much food, though, grows underground. To eat, mammals had to travel above the ground – but the safest time to forage was at night, when dinosaurs were less of a threat. Evolving to be warm-blooded meant mammals could move at night. That solution came with a trade-off, though: Mammals had to eat a lot more food than dinosaurs per unit of weight in order to maintain their high metabolism and to support their constant inner body temperature around 99 degrees Fahrenheit (37 degrees Celsius)."  

The section ends with Vyshedskiy making unfounded claims about memories being stored using the cortex and the hippocampus. That's what neuroscientists do to try and make it sound as if they have some understanding of how humans could store and retrieve memories, something no neuroscientist can credibly explain. When someone lacks a "how" they will try using a "where" and hope you don't notice that they failed to give you a "how." For example:

Joe: "You built a time machine? You expect me to believe that?"
John: "Well let me give you the exact details. I built it in my garage."

I won't bother to dispute here Vyshedskiy's claims about the hippocampus (inconsistent with data discussed here), because they have no relevance to the main question I am discussing here, which is whether Vyshedskiy has done anything to explain human imagination.  After the end of his "From bacteria to mammals" section that says nothing relevant to explaining human imagination, Vyshedskiy's next section is entitled "Involuntary made-up 'memories.' " In this section he discusses dreaming. I suppose dreaming can be considered a form of imagination.  But Vyshedskiy  does nothing to explain any neural basis for dreaming. He makes the irrelevant insinuation that dreaming evolved 140 million years ago (a speculation no could ever substantiate), and the unfounded claim that scientists have "demonstrated that animals can 'dream' of going places they’ve never visited before." He supports this claim only by a reference to a poor quality study using the way-too-small study group size of only four rats. 

The rest of the section Vyshedskiy fills up with anecdotes about people who supposedly had important ideas inspired by dreams. Such stories do nothing to explain how a brain could produce ideas either through dreaming or conscious imagination.  We have no understanding of how a brain could produce dreaming, so mentioning dreaming does nothing to explain imagination. The very important "Dream Catcher" study showed that scientists could not even predict whether someone was dreaming by analyzing their brain waves. I discuss that study in my post here

Vyshedskiy's final section is entitled "Imagining on purpose."  The first six sentences are some filler material consisting of obvious truths that don't tell us anything we didn't already know long ago, sentences such as "When asked to mentally combine two identical right triangles along their long edges, or hypotenuses, you envision a square." Then Vyshedskiy tries giving us not a "how" but a "where," as neuroscientists tend to do when they lack any credible "how." He says this:

"This deliberate, responsive and reliable capacity to combine and recombine mental objects is called prefrontal synthesis. It relies on the ability of the prefrontal cortex located at the very front of the brain to control the rest of the neocortex."

We hear nothing backing up these claims, which are not well-founded. See my post "Reasons for Doubting Thought Comes from the Frontal Lobes or Prefrontal Cortex" for neuroscience evidence that contradicts such a claim.  The scientific paper here tells us that patients with prefrontal damage "often have a remarkable absence of intellectual impairment, as measured by conventional IQ tests." The authors of the scientific paper tried an alternate approach, using a test of so-called "fluid" intelligence on 80 patients with prefrontal damage. They concluded "our findings do not support a connection between fluid intelligence and the frontal lobes." Table 7 of this study reveals that the average intelligence of the 80 patients with prefrontal cortex damage was 99.5 – only a tiny bit lower than the average IQ of 100. Table 8 tells us that two of the  patients with prefrontal cortex damage had genius IQs of higher than 140. In a similar vein, the paper here tested IQ for 156 Vietnam veterans who had undergone frontal lobe brain injury during combat. If you do the math using Figure 5 in this paper, you get an average IQ of 98, only two points lower than average. You could plausibly explain that 2 point difference purely by assuming that those who got injured had a very slightly lower average intelligence (a plausible assumption given that smarter people would be more likely to have smart behavior reducing their chance of injury). Similarly, this study checked the IQ of 7 patients with prefrontal cortex damage, and found that they had an average IQ of 101.

The term "prefrontal synthesis" used by Vyshedskiy is not a standard term used by neuroscientists, and a search for uses of the term "prefrontal synthesis" on Google scholar will show that pretty much no one other than Vyshedskiy (or people referring to his work) are using such a term. After making the paragraph quoted above, Vyshedskiy offers no evidence to support it. Instead he gives us two paragraphs discussing the earliest archaeological evidence for imaginative or symbolic thinking by humans, which he dates to be about 70,000 years old. He calls this  an "abrupt change in imagination." Yes, we suddenly see in the archaeological record about 70,000 years ago evidence that imaginative and symbol-using humans first existed. But why would such an "abrupt change in imagination" have occurred if imagination came from the brain? It could not have. There was no noticeable change in human brains around that time. In the university press release here, we get this quote from  anthropologist Brian Villmoare: "We re-examined the dataset from DeSilva et al. and found that human brain size has not changed in 30,000 years, and probably not in 300,000 years.” 

Vyshedskiy has failed to see how he is undermining his own claims of brain-caused imagination by citing such facts. If you first consider a sudden explosion of human imagination (with the first appearance of art and symbolism) about 70,000 years ago, and then consider that there was no change in brain size at that time, that is collectively a set of facts standing against the claim that imagination comes from the brain. All that he says to try to smooth over this discrepancy is this sentence: "Genetic analyses suggest that a few individuals acquired this prefrontal synthesis ability and then spread their genes far and wide by eliminating other contemporaneous males with the use of an imagination-enabled strategy and newly developed weapons." The reference is to a scientific paper that suggests no such thing. In fact, the paper ("Evidence that two main bottleneck events shaped modern human genetic diversity") does not mention brains, does not mention cortex tissue, does not mention the prefrontal cortex and does not mention intelligence, imagination, thinking or creativity. The paper has no relevance to such topics. 

This is the last assertion of any substance that Vyshedskiy says on this topic, and it's a groundless assertion lacking any credibility : the wild speculation that humans got imagination (which Vyshedskiy seems to like calling "prefrontal synthesis") because "a few individuals acquired this prefrontal synthesis ability" and then spread their genes around. But how could a few humans without bigger brains have suddenly become the first humans with the ability to imagine things?  Vyshedskiy has no credible tale to tell of how human beings are able to imagine things, and his essay (offering no substantive ideas on this topic) ends up with some vague silly speculation that maybe there was some genetic luck that suddenly gave humans the ability to imagine things. Such speculation is mere hand-waving. 

At the first link in the search results returned here, you can find a paper by Vyshedskiy that shows quite a speculative tendency on such topics. On page 20 of the paper with a very long title referring to a "Romulus and Remus hypothesis," he says this: 

"Furthermore, since only children can acquire PFS [prefrontal synthesis], it follows that around 70,000 years ago young children must have invented the first recursive language....Accordingly, we named our hypothesis after the celebrated twin founders of Rome, Romulus and Remus. Similar to legendary Romulus and Remus whose caregiver was a wolf, the real children’s caregivers had an animal-like communication system with many words but no recursion."

The origin of human language is actually a mystery that our scientists have made no real progress in solving, and one that cannot be solved restricting yourself to materialist assumptions (as I explain here). You're hardly making progress on this intractable problem if you say, "A pair of little kids did it!"  I offer Vyshedskiy's recent essay on imagination as Exhibit A that neuroscientists have no credible tale to tell of how a brain could ever imagine anything. Similar examples can be found in my posts below:
We have a very different state of affairs regarding memory and imagination. Humans do build devices that are capable of permanently storing and instantly retrieving information, devices such as computers. So in the case of memory, we can make a list of the set of things that computers have that allow them to permanently store and instantly retrieve information, and ask ourselves: does the brain have any such things? The correct answer is: the brain has no such things (as I explain in my post here).  For example, computers have an addressing system and a read/write unit for writing and reading from one particular address, but the brain has no such things.  

But in the case of imagination, it is a very different state of affairs. Humans have never built any devices that have imagination like humans have. Digital computers have no imagination. So we cannot make a list of the type of characteristics that a system would have if it could imagine things.  We can merely say: we can imagine no conceivable arrangement of matter that would cause some matter to acquire a power of imagination it did not have before such an arrangement.  Such an impossibility is a strong argument against all claims that imagination comes from the brain.  There is no conceivable arrangement of biological material that we should expect to produce an ability to imagine. 

Dore illustration
Imaginative art by Gustave Dore

On this matter, don't be fooled by computer programs sold as examples of creativity. Such things are simply computer programming and data processing that involve no real imagination. One example is an "idea generator" program that works by simply making novel combinations of words. That involves no real imagination. Then there are programs such as ChatGPT that seem to have a story generation ability. I explain in my essay here how such supposed creativity is probably generated by web-crawling activity that slowly crawls the internet, finding millions of stories, and converting them (by use of replacing specific names with placeholders) into story templates that are each little types of story-generators. Such story generation "creativity" is fueled by grabbing countless cases of human creativity, and is not true machine creativity or machine imagination. 

The paper "Neural substrates of envisioning the future" describes a study looking for neural correlates of imagination. 21 subjects were brain scanned while they did three tasks: remembering an event in their past (such as a birthday in the past), imagining an event in their future (such as a future birthday they would have), or imagining an event in someone else future.  Figure 1 shows unimpressive results, with percent signal changes no greater than about 1 part in 200, which are the kind of differences one would expect to get from random fluctuations, even if people don't use their brains for imagining or remembering.  We read of a "statistically indistinguishable pattern of activity across time while subjects envisioned their personal future (SF) and recollected the past (SR) in response to a series of event cues (e.g., Birthday)."  The results when people were "imagining a future individual in similar scenarios" also fail to show any clear sign of neural involvement, with percent signal changes no greater than about 1 part in 200.  

Sunday, April 16, 2023

Human Thoughts and Memory Are Gigantically Connective, But Brains Have Only Low Connectivity

The human mind and human memory are gigantically connective. A person's thoughts can quickly dart around between vastly different areas of human knowledge. For example, suppose you ask me, "How could modern technology have made a difference if the ancient Romans had possessed it?" Darting around instantly between many different pieces of knowledge in my memory, I might very quickly give an answer like this:

"It's easy to think of many different ways modern technology could have made a difference around the time of Julius Caesar and Octavian. Julius Caesar might have avoided his assassination, maybe by wearing a Kevlar vest and Kevlar collar, or maybe by installing metal detectors at the Senate building. Mark Antony might have won the battle of Actium, by having jet fighters bomb the ships of Octavian into pieces. The Romans might have used tanks and bombers to wipe out the barbarian hordes, preventing the fall of Rome from ever happening. And with smartphones and TV helping everyone to instantly communicate, there would been none of the 'too big an empire' problem that plagued the Romans. The Roman empire might have spread across half of Eurasia."

Or, to give another example, when asking myself, "Name some famous Johns," I quickly wrote down the following, extracting things from a variety of historical eras, and from both fact and fiction:

"Well there's Prince John and Little John in the Robin Hood story. And there's John the author of one of the gospels. Then there's John Updike, an American writer. And there's the famous assassin John Wilkes Booth. Then there's Pope John Paul II. And there's John Lennon.  And Johnny Walker and Johnny Carson. Then there's US presidents John Adams and John Quincy Adams. Then there's John Brown who raided Harper's Ferry. And don't forget the scientist John Dalton."

It seems that the human mind and human memory are gigantically connective. But does the human brain have any degree of connectivity that can explain the almost perfect connectivity of the human mind and human memory? A person might claim that the brain has perfect connectivity, on the grounds that it is possible to trace a path between any two regions of the brain. But it would be hasty to draw a conclusion about brain connectivity from so simple a fact. Analyzing how connective the brain is turns out to be a much more complicated task. 

Neurons in the brain can be analyzed as nodes in a network. With any network there are ways of quantifying how connective the network is. Some important questions may be asked to judge the connectivity of a network:

(1) What is the ratio between the total number of nodes in the network and the total number of connections between nodes in the network?

(2) What percentage of the total nodes in the network is the average node in the network directly connected to?

(3) What is the average time needed to communicate between two random nodes of the network?

(4) How reliably does a signal travel between two nodes in the network?

Let me give some very simple examples of answering some of these questions. Let's consider the very simple network shown below:

Here is a partial analysis of this network's connectivity:

Number of nodes: 7.

Number of connections: 12.

Average number of connections per node: 3.28.

What fraction of the total nodes in the network is the average node in the network directly connected to? 3.28 divided by 7, or .468

A network with  higher connectivity is shown below:


Here is a partial analysis of this network's connectivity:

Number of nodes: 7.

Number of connections: 17.

Average number of connections per node: 4.57.

What fraction of the total nodes in the network is the average node in the network directly connected to? 4.57 divided by 7, or .65, which is roughly two-thirds.

It is the last question that gives us the "bottom line" on how much connectivity the network has. The first network has a "bottom line" connectivity of only .468, but the second network has a substantially higher "bottom line" connectivity of .65.  A network with perfect connectivity would have a "bottom line" connectivity of 1.0. 

Now, having got a bit "warmed up" in analyzing the connectivity of networks, let us consider the question: just how connective is the human brain? We can use the same format as above.

Number of nodes: about 100 billion (which is the number of neurons in the human brain).

Number of connections: about 100 trillion (which is the number of synapses in the human brain, each neuron having an average of about 1000 synapses).

Average number of connections per node: about 1000. Although it is sometimes claimed there are thousands of synapses per neuron, the 2021 study here (Table 1) finds fewer than 100 connections per neuron in primates, finding 25 excitatory synapses per neuron in primates and 44 inhibitory synapses per neuron in primates.

What percentage of the total nodes in the network is the average node in the network directly connected to? 1000 divided by 100 billion, or 0.00000001.

We are left with a shockingly low "bottom line" number on the connectivity of the human brain. The human brain would seem to have a connectivity very, very many times lower than the two networks depicted above. The "bottom line" connectivity of the brain is a number only about 1 in 100 million. 

Here are some interesting findings from the neuroscience literature. The source here says, "Electrophysiological studies detect connections only in approximately 10% of pairs of neurons." This would seem to mean that when scientists check whether two neurons right next to each other are connected, they find that in only about 1 case in 10 are such neurons connected. Referring to a type of brain structure in which neurons are rather densely packed (pyramidal cells), the paper states, "Virtually all electrophysiological studies in vitro find connection probabilities of order 0.1–0.2 for pairs of nearby pyramidal cells."

Using older and different estimates about the number of brain cells and the number of connections (synapses) between brain cells, a scientific paper ("Is the brain really a small-world network?") states the following:

"On average, the density of human brain connectivity at the cellular level is very sparse. The average number of synapses of neurons (~104) (Braitenberg and Schüz 1998) divided by the number of neural elements (~1010) (Herculano-Houzel 2012) results in a very low average probability of any two neurons in the brain making contact (10−6), implying a highly dispersed network." 

The paragraph above is telling us that if you were to pick two random neurons in the brain, there would be only about 1 chance in a million that they are directly connected. It seems that the connectivity of neurons in the brain is very low, way too low to explain the almost perfect connectivity of ideas, thoughts and memories in the human mind. 

There are two other crucial factors we should consider when considering the connectivity of the brain:

(1) How fast do signals travel between neurons?

(2) How reliably does a signal travel when it passes between two neurons?

Considering the first of these questions, the widely quoted figure of about 100 meters per second for brain signals is very misleading. That is the fastest that a signal can travel in any part of the brain, when signals pass through myelinated axons. But most axons in the cortex are not myelinated, and most of the tissue in the brain consists of relatively slow dendrites. According to neuroscientist Nikolaos C Aggelopoulos, there is an estimate of 0.5 meters per second for the speed of nerve transmission across dendrites (see here for a similar estimate). That is a speed 200 times slower than the nerve transmission speed commonly quoted for myelinated axons. Then there is the enormous slowing factor caused by the need for brain signals to cross across synapses, serious "speed bumps" that should slow down brain signals very much. 

slow speed of brain signals

There is a scientific term used for the delay caused when a nerve signal travels across a synapse. The delay is called the synaptic delay. According to this 1965 scientific paper, most synaptic delays are about .5 milliseconds, but there are also quite a few as long as 2 to 4 milliseconds. A more recent (and probably more reliable) estimate was made in a 2000 paper studying the prefrontal monkey cortex. That paper says, "the synaptic delay, estimated from the y-axis intercepts of the linear regressions, was 2.29" milliseconds. It is very important to realize that this synaptic delay is not the total delay caused by a nerve signal as it passes across different synapses. The synaptic delay is the delay caused each and every time that the nerve signal passes across a synapse. 

Such a delay may not seem like too much of a speed bump. But consider just how many such "synaptic delays" would have to occur for, say, a brain signal to travel from one region of the brain to another. It has been estimated that the brain contains 100 trillion synapses (a neuron may have thousands of them).  So it would seem that for a neural signal to travel from one part of the brain to another part of the brain that is a distance away only 5% or 10% of the length of the brain, that such a signal would have to endure many thousands of such "synaptic delays" requiring a total of quite a few seconds of time. 

There is no reason to think that the average speed of signals in the brain should be much faster than the speed at which electrical signals travel around the brain during seizures. The paper here lists a speed of only about 1 millimeter per second for seizures in the human brain, saying, "Seizures propagate slowly to connected areas with speeds on the order of 1 mm/s."  There is no reason to think that some hypothetical brain signals involved in thinking would occur much faster than seizures. 

How reliably does a signal travel when it passes between two neurons? It has been repeatedly stated in neuroscience literature that brain signals travel across chemical synapses with a reliability of only .5 or smaller, and almost all synapses in the brain are chemical synapses.  In an interview, an expert on neuron noise states the following:

"There is, for example, unreliable synaptic transmission. This is something that an engineer would not normally build into a system. When one neuron is active, and a signal runs down the axon, that signal is not guaranteed to actually reach the next neuron. It makes it across the synapse with a probability like one half, or even less. This introduces a lot of noise into the system."

 A scientific paper tells us the same thing. It states, "Several recent studies have documented the unreliability of central nervous system synapses: typically, a postsynaptic response is produced less than half of the time when a presynaptic nerve impulse arrives at a synapse." Another scientific paper says, "In the cortex, individual synapses seem to be extremely unreliable: the probability of transmitter release in response to a single action potential can be as low as 0.1 or lower."

A 2020 paper states this:

"Neurons communicate primarily through chemical synapses, and that communication is critical for proper brain function. However, chemical synaptic transmission appears unreliable: for most synapses, when an action potential arrives at an axon terminal, about half the time, no neurotransmitter is released and so no communication happens... Furthermore, when neurotransmitter is released at an individual synaptic release site, the size of the local postsynaptic membrane conductance change is also variable. Given the importance of synapses, the energetic cost of generating action potentials, and the evolutionary timescales over which the brain has been optimized, the high level of synaptic noise seems surprising."

Such a result (a very serious brain physical shortfall) is surprising only to those who believe that your brain stores your memories and that your brain makes your mind.  Those who disbelieve such a thing may expect exactly such shortfalls to be repeatedly found. 

To summarize, there are three gigantic reasons why a human brain cannot be regarded as any kind of high-connectivity network:

(1) The "bottom line" connectivity of the brain (as defined above) is very low, with the average neuron being directly connected to fewer than 1 in a million of the brain's neurons, and as few as 1 in 100 million of the brain's neurons. 

(2) You cannot assume that this shortfall is fixed by signals traveling reliably between many neurons (such as from Neuron 1 to Neuron 2 to Neuron 3 to Neuron 4 to Neuron 5 to Neuron 6), because the reliability of signal transmission across synapses is so low that the signal would very probably be lost when even trying to pass across only four different neurons.

(3) Very serious slowing factors such as the low transmission speed of dendrites and synaptic delays should worsen brain connectivity even further. 

Your mind and memory are almost perfectly connective. But your brain has poor physical connectivity. Such a discrepancy is one of very many reasons for thinking that your brain cannot be the source of your mind. 

Postscript: The 2022 paper "What Kind of Network Is the Brain?" by John D. Mollon  and others gives us some facts that cast doubt on claims that the brain is a very highly connected network. We read this:

"Excluding callosal neurons, efferent neurons, and all non-pyramidal cells, they estimate that the total number of neurons making ipsilateral connections within one hemisphere is 6 × 109. However, they estimate that there are only ~108 axons in all the major long-range tracts combined. Thus, of all the cells that make cortico-cortical connections, most are local in their projections, and only ~2% have access to the long-range tracts within one hemisphere (and the proportion having access to any individual tract is likely to be still smaller) [46]. The proportion of non-efferent cells contributing axons to the corpus callosum is similarly ~2%.

The estimates obtained by Schüz and Braitenberg were based on classical histology, but they draw confirmation from a recent analysis of diffusion MRI (dMRI) data. Rosen and Halgren [48] analyzed tractography data for 1065 individuals in the Human Connectome Project. They calibrated their dMRI measure by reference to the known density of axons in the corpus callosum and the cross-sectional area of the corpus callosum of each individual (obtained by structural MRI). They then used this conversion factor to estimate the number of axons in the long-distance fasciculi. For each of the 360 'parcels' [49] of cortex, they calculated the number of fibers connecting to every other parcel. Long-range connections (callosal plus intra-hemispheric) were sparse, about 3.7% in total – a value close to Schüz and Braitenberg's estimate of 4%. The limited capacity of the long-distance tracts is difficult to reconcile with models that suppose the brain is a meta-net [9] or with accounts of memory in which cell assemblies depend on many long-range excitatory connections. [50]"