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大腦神經學：意識篇 – 開欄文
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瀏覽1,437 ｜回應10｜推薦1 |
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我求知的主要興趣從倫理學轉向認知科學後，偶而會涉及到一些討論「意識」的科普書籍。讀了恰爾莫斯教授的《具有意識的心靈：追求基本理論》一書後，在我(自以為)了解該書意旨範圍內，我對他「經驗本質」概念和「意識研究上的困難議題」說法兩者，都持存疑態度。自然也就使得我在過去20多年中，進一步讀了不少關於「意識」的書籍以及研究報告。我收集了相當多這方面的論文；本部落格在過去曾經轉載了一些。我也試圖系統性寫下自己的觀點；但因為功力不足，寫寫停停一直無法成章。
在倫理學之外，這是我最希望能把過去讀書心得整理出來的一個領域。先轉載我認為有爭議的兩篇文章來起個頭。
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昏迷病患的意識狀態 ---- Aria Bendix
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先進儀器能夠更精準的測出：昏迷病患是否仍然有「隱蔽知覺」。
Brain scans of some unresponsive hospital patients show detectable activity
Scans suggest many people with severe brain injuries are more aware than originally thought.
Aria Bendix, 08/18/24
When a patient with a brain injury is unresponsive, doctors turn to certain basic tests to see if they could still have some awareness: calling their name, clapping near their ear or inserting a cotton swab in their nose.
Those who don’t wake up are often believed to have lost consciousness.
But a new study suggests that a quarter of brain-injured patients who don’t physically respond to commands are doing so mentally. The results were published this week in the New England Journal of Medicine.
The study looked at 353 patients who, from the outside, seemed to have lost consciousness due to a brain injury. The sources of these injuries varied from accidents to heart attacks and strokes. Of those patients, 241 were diagnosed as being in a coma, a vegetative state or having only minimal consciousness.
The researchers gave the patients verbal commands, like telling them to imagine themselves swimming or to open and close their hands. For 60 of the 241 patients, there was evidence that they could still perform those tasks in their head. The study refers to this as “cognitive motor dissociation.” Some doctors prefer the term “covert awareness.”
The mental tasks were demanding enough that even some of the other patients who had recovered enough to physically respond to verbal queues couldn’t perform them, said Dr. Nicholas Schiff, an author of the study and a neurologist at Weill Cornell Medicine.
The findings suggest that covert awareness is more common than originally thought: Small studies previously estimated that around 10%-20% of unresponsive patients had it. The new study is larger than its predecessors.
“It’s both an incredible finding, but also kind of scary,” said Caroline Schnakers, assistant director of the Casa Colina Research Institute, who studies the same phenomenon but was not involved in the new research.
The idea that so many patients “could be able to at least respond to their environment, but are not given the right tools for doing so — that’s very alarming for clinicians,” she said.
Schiff said 1 in 4 patients is likely a conservative estimate.
“We know we missed people,” he said. “We also know that patients who have severe brain injury have what are called fluctuations in arousal. They have good and bad times of the day.”
His team measured patients’ mental activity through brain wave tests and functional MRIs. Unlike a standard MRI, which produces 3D images of the brain, a functional MRI measures activity in the brain based on blood flow. When conscious people are told to follow a command, certain areas of the brain become more active, and blood flow to these areas will increase.
Not all hospitals have this technology, however, meaning doctors could miss out on diagnosing patients. Many hospitals use CAT scans or standard MRIs — along with physical exams — to determine if a patient’s mind is still active. If those tests don’t show signs of consciousness, doctors may falsely assume there’s no hope for improvement.
“They’re going to be treated as if they’re fully unresponsive,” Schiff said. “No one’s going to guess that they’re there.”
Dr. David Greer, chair of the neurology department at Boston University School of Medicine, pointed to one limitation of the study: The patients didn’t all have the same injuries or level of brain dysfunction.
“It’s a fairly heterogeneous group, and I think that has to be a caveat,” said Greer, who wasn’t involved in the research.
Schiff, however, said brain dysfunction tends to be relatively similar across injuries.
Among the patients in his study, young people and those with traumatic brain injuries — the kind linked to external events like falls or car crashes — were more likely to have covert awareness.
“Traumatic brain injury patients are notorious for looking really bad for weeks to even months, and then having a remarkable delayed recovery at six months or 12 months,” Greer said. “Those are the ones that I’m always super cautious about to make sure I’m not making any snap judgments.”
But he noted that even if a patient is conscious, it’s not a guarantee that they’ll return to their normal lives one day.
“The worst message that people can take from this as a family is to say, ‘Oh, they’re in there and they’re going to make a full recovery,’” Greer said. “I think that would be very misleading for families to have that kind of false hope, because many if not most of these patients will still have a severe disability.”
But the findings do offer hope for connecting patients to certain treatments in the future. For now, the options are limited: A Parkinson’s drug, amantadine, has shown some promise in helping people recover consciousness. Some doctors also prescribe Ambien, stimulants or antidepressants.
Brain implants or neuromodulation (using electrical currents to alter brain activity) could represent the next wave of treatments, Schnakers said. She emphasized the need to provide families with options for their loved ones.
“The family will ask, ‘What can we do?’ It’s actually something that we have not thought about very seriously,” she said, adding: “This is not acceptable anymore.”
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《意識理論小百科》簡介 ----- Àlex Gómez-Marín
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Seeing the consciousness forest for the trees
Towards a map of consciousness
Àlex Gómez-Marín, 07/25/24
編者前言：
The American public intellectual and creator of the television series Closer to Truth, Robert Lawrence Kuhn has written perhaps the most comprehensive article on the landscape of theories of consciousness in recent memory. In this review of the consciousness landscape, Àlex Gómez-Marín celebrates Robert Kuhn’s rejection of the monopoly of materialism and uncovers the radical implications of these new accounts of consciousness for meaning, artificial intelligence, and human immortality.
The scientific study of consciousness was not sanctioned by the mainstream until the nineties. Let us not forget that science stands on the shoulders of giants but also on the three-legged stool of data, theory, and socio-political wants. Thirty years later, the field has grown into a vibrant milieu of approaches blessed and burdened by covert assumptions, contradictory results, and conflicting implications. If the study of behaviour and cognition has become the Urban East, consciousness studies are the current Wild West of science and philosophy.
The American public intellectual, international corporate strategist, and PhD in neurophysiology, Robert Lawrence Kuhn is one of the few pioneers attempting to provide some comprehensive order to such a vexed matter. In a recent article entitled “A landscape of consciousness: Toward a taxonomy of explanations and implications”, the creator and host of the public television series Closer to Truth has begun to rescue such an ultimate frontier of human knowledge from the sterile provincial quarrels, egocentric delusions of grandeur, and myopic glares that plague the field of consciousness research.
The origins of our perplexity in making sense of experience itself can be traced back to Galileo Galilei, who programmatically excluded subjective experience from the purview of science. One can interpret this sagacious move as a means to understand nature in two phases: let us first start with what lends itself to measurement and mathematisation (the “primary phenomena of motion and touch”, in Galileo’s words) and leave for later what resists it. “I think that tastes, odors, colors, and so on (…) reside only in consciousness”, he wrote in The Assayer in 1623.
Such a strategy proved tremendously successful, giving rise to physics, then chemistry, next biology, and finally psychology. The progression of scientific disciplines reaped great (but progressively diminishing) returns. Studying matter is, no doubt, hard. But there is something about life and mind that particularly defies the so-called scientific method. Four hundred years later, we can’t ignore the elephant in the room anymore: experience is what makes science possible and yet a proper science of consciousness seems unattainable. The Galilean knot remains untied. Today we call it “the hard problem”.
It is ironic and fascinating to note that the hard problem of consciousness has amplified the “toothbrush problem” of theorists. Consciousness researchers treat their explanations much like toothbrushes: everyone has their own, but nobody wants to use someone else’s. Moreover, until quite recently, most researchers could only get their toothpaste in the supermarket monopoly of materialism, a philosophical doctrine often presented as a scientific fact. But things are changing. To hold on to the analogy, an orthodontics of consciousness is coming about. New comprehensive views are allowing to expand our jaws, correct misplaced teeth, and prevent misaligned bite patterns.
Kuhn’s review is a paradigmatic instance of such an individual and collective reckoning. His is not a normal piece of work. It is a beauty and a beast—a unique creature in content and style. It could have been a book, but he decided to publish his magnum opus in the journal Progress in Biophysics and Molecular Biology as open-access 142-page double-column article. The piece is 175 thousand words long, including nearly a thousand references. In it, Kuhn articulates a taxonomy of about 225 theories of consciousness.
Gathering under the same roof most of the greatest contemporary thinkers of one of the greatest questions one can ever try to answer, Kuhn’s landscape enacts the quasi-extinct art of true scholarship. Very few scholars can see beyond their theoretical bellies, nor would devote the time and effort necessary to put such a myriad of views together with his exquisite intellectual humility and rigour. The living proponents (too often deadly opponents) will still agree to disagree but, at least, they can now see the forest for the trees.
The landscape comprises 10 major categories and it is organised in a gradient of “isms”, from die-hard materialist positions to mind-only propositions. Materialism gets a great deal of space and attention with nearly a hundred authors nested in 10 subcategories, such as neurobiological, computational and informational, homeostatic and affective, embodied and enactive, representational, etc. The landscape also makes some dualisms respectable. The (false) two-alternative forced choice between (promissory) materialism and (ridiculed) dualism is over. Materialism is not the only game in town anymore. Quantum approaches to consciousness do have their deserved place too. We then encounter a great range of fascinating kinds of panpsychism, monism, and idealism. Integrated Information Theory has its own category, remaining the only scientific approach that is philosophically unclassifiable in the landscape.
Remarkably, Kuhn devotes an entire section to “anomalous and altered states”, describing decades-long serious scientific investigations on taboo topics such as extra-sensory perception and survival of consciousness after bodily death. I call them “the edges of consciousness” because they are true frontiers of knowledge and also marginalised (stigmatised and/or ignored) by dogmatic skeptics. The final category gathers “challenge theories” which point to the intractability of the mind-body problem. The piece ends underscoring the implications of all such explanations of consciousness for ultimate meaning, artificial intelligence, and human immortality.
Apart from the imperative presence of the godfathers of the field such as Christof Koch and David Chalmers (and along with other legendary philosophers and neuro-celebrities), it is delightful to find a series of not-so-popular but crucial authors such as David Bentley Hart, Michel Bitbol, David Bohm, Jacobo Grinberg, Dean Radin, Rupert Sheldrake, Rudolf Steiner, and Ian Stevenson. When was the last time you read a piece cordially inviting philosophy, neuroscience, quantum physics, psychical research, theology, and religion to the same table?
Yes, the map is not the territory (nor the terrain). Yes, all models are ultimately wrong (but some are more useful than others). Yes, too often we conflate models with captivating metaphors or cartoonish mechanisms enacting covert metaphysics. And yes, most theories of consciousness aren’t mathematically formulated nor empirically testable. Shall we then rush to prune the landscape? Not yet.
Let us enjoy a real taste of epistemic and metaphysical pluralism after years of philosophical monotheism and neuroscientific chauvinism. Of course brains play a key role in consciousness. But the real question, as William James saw more than a century ago, is whether their function is productive or permissive. Much like the picture of Earth that astronaut William Anders took from the Moon during the Apollo 8 mission, Kuhn’s landscape simultaneously offers an orienting and disorienting experience. We need a larger Overton window from which to contemplate what we know, what we don’t, and what we think we do but actually ignore.
At the end of the day, beyond the sweet dopamine hit of seeing one’s name in the hall of fame, Kuhn’s forest may reveal to each and every fervent tree advocate that they are all missing the point but, additionally, that they all have a point. As Leibniz wrote in a letter to Nicolas Remond in 1714, “I have found that most of the sects are right in a good part of what they propose, but not so much in what they deny”. Isn’t it both commendable and ludicrous to realise that hundreds of extremely clever people think they solved the problem of consciousness and are convinced that everyone else is wrong?
Kuhn’s faithful description of each position without the urge to adjudicate deserves nothing but praise and gratitude. This uncommon ability is an urgent antidote to the academic vice of hearing only one’s own voice while shouting at each other. In fact, if there is something more interesting than consciousness itself is the sociology of its researchers. Let us leave the consciousness hunger games behind and realise that there is plenty of food for thought for everyone. Rather than divide and conquer, let us unite and wonder.
表單的底部Àlex Gómez-Marín：
Theoretical physicist and neuroscientist, professor at the Instituto de Neurociencias of Alicante in Spain, and director of the Pari Center in Italy.
Related Posts：
The chemical roots of consciousness
Consciousness came before life
Gödel and the nature of the mind
Consciousness does not require a self
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SUGGESTED VIEWING：
The mystery of emergence With Suchitra Sebastian, Hilary Lawson, Philip Goff, Jack Symes
Models, metaphors and minds With Kenneth Cukier, Mark Salter, Peter Sjöstedt-H, Joanna Bryson
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意識的性質和如何享受有意識的樂趣--LINDSEY LAUGHLIN
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我不是大腦神經學家；但不客氣的說，就 “psychoactive substances” 這部份的論述而言(下文倒數第二段)，讓我懷疑寇合博士已經走火入魔。他可說是李蕊博士2.0。
我頗難苟同下文所呈現寇合博士對「意識」的觀點；但我一時沒有精力整理出我的淺見；或許掛掉以前能找時間談談。
對「意識」議題有興趣的朋友，可參見以下相關報導/評論：《意識可靠幻覺論》、《現實與對現實的認知》、和本欄2024/05/09等多篇貼文。
The nature of consciousness, and how to enjoy it while you can
In his new book, Christof Koch views consciousness as a theorist and an aficionado.
LINDSEY LAUGHLIN, 05/18/24
Unraveling how consciousness arises out of particular configurations of organic matter is a quest that has absorbed scientists and philosophers for ages. Now, with AI systems behaving in strikingly conscious-looking ways, it is more important than ever to get a handle on who and what is capable of experiencing life on a conscious level. As Christof Koch writes in Then I Am Myself the World, "That you are intimately acquainted with the way life feels is a brute fact about the world that cries out for an explanation." His explanation—bounded by the limits of current research and framed through Koch’s preferred theory of consciousness—is what he eloquently attempts to deliver.
Koch, a physicist, neuroscientist, and former president of the Allen Institute for Brain Science, has spent his career hunting for the seat of consciousness, scouring the brain for physical footprints of subjective experience. It turns out that the posterior hot zone, a region in the back of the neocortex, is intricately connected to self-awareness and experiences of sound, sight, and touch. Dense networks of neocortical neurons in this area connect in a looped configuration; output signals feedback into input neurons, allowing the posterior hot zone to influence its own behavior. And herein, Koch claims, lies the key to consciousness.
In the hot zone
According to integrated information theory (IIT)—which Koch strongly favors over a multitude of contending theories of consciousness—the Rosetta Stone of subjective experience is the ability of a system to influence itself: to use its past state to affect its present state and its present state to influence its future state.
Billions of neurons exist in the cerebellum, but they are wired “with nonoverlapping inputs and outputs ... in a feed-forward manner,” writes Koch. He argues that a structure designed in this way, with limited influence over its own future, is not likely to produce consciousness. Similarly, the prefrontal cortex might allow us to perform complex calculations and exhibit advanced reasoning skills, but such traits do not equate to a capacity to experience life. It is the “reverberatory, self-sustaining excitatory loops prevalent in the neocortex,” Koch tells us, that set the stage for subjective experience to arise.
This declaration matches the experimental evidence Koch presents in Chapter 6: Injuries to the cerebellum do not eliminate a person’s awareness of themselves in relation to the outside world. Consciousness remains, even in a person who can no longer move their body with ease. Yet injuries to the posterior hot zone within the neocortex significantly change a person’s perception of auditory, visual, and tactile information, altering what they subjectively experience and how they describe these experiences to themselves and others.
Does this mean that artificial computer systems, wired appropriately, can be conscious? Not necessarily, Koch says. This might one day be possible with the advent of new technology, but we are not there yet. He writes. “The high connectivity [in a human brain] is very different from that found in the central processing unit of any digital computer, where one transistor typically connects to a handful of other transistors.” For the foreseeable future, AI systems will remain unconscious despite appearances to the contrary.
Koch’s eloquent overview of IIT and the melodic ease of his neuroscientific explanations are undeniably compelling, even for die-hard physicalists who flinch at terms like “self-influence.” His impeccably written descriptions are peppered with references to philosophers, writers, musicians, and psychologists—Albert Camus, Viktor Frankl, Richard Wagner, and Lewis Carroll all make appearances, adding richness and relatability to the narrative. For example, as an introduction to phenomenology—the way an experience feels or appears—he aptly quotes Eminem: "I can’t tell you what it really is, I can only tell you what it feels like."
Going beyond consciousness’ limits
The takeaway from the first half of Then I Am Myself the World is that IIT might offer the best-fit explanation for consciousness—a view, it’s worth mentioning, that is highly contested by many other neuroscientists. But the greater message, addressed later on, is that we, as human beings, have the capacity to expand and transform our own conscious experiences. Why settle for a life lived in semi-darkness when we can pull back the curtains and experience an explosion of light?
Koch discusses transformative states of consciousness in the second half of his book, including near-death, psychedelic, and mystical experiences. He also discusses the expansive benefits of sustained exercise—drawing upon his personal experiences as a bicyclist and rock climber—through which a person can enter “the zone.”
“Some consider these states a higher form of consciousness. Perhaps. I call them transformative ... transformative experiences achieve transcendence, conveying a sense of equanimity, a feeling that everything is as it should be.” He places special emphasis on ‘the flow,’ which he defines as “a mental state in which you are totally engaged with the world while only dimly aware of yourself.” Being in the flow, also known as direct awareness, is the experience of being completely present.
Notably, the posterior hot zones of Buddhist monks, who spend years training themselves to quiet mental noise through meditation, are silenced during states of pure presence. EEG measurements confirm this; a dearth of electrical activity in the brain, especially in the neocortex, translates into the experience of calm, immediate awareness. It seems likely, Koch says, that psychoactive substances and near-death experiences have a similar effect on the posterior hot zone, triggering experiences of “boundless space ... without body, without self, and without time.”
Yet, the average individual has few opportunities to experience such neocortical quieting. “As a denizen of the twenty-first century, you only rarely experience the spontaneity of this stream,” he writes. Yet, it is this silent space that he suggests makes one feel most connected and engaged with the direct experience of life.
Koch suggests that exercise, meditation, and the occasional guided psychedelic might be beneficial to many people. Substances such as psilocybin can enhance one’s feeling of well-being and facilitate pure presence. It is rare to have a close brush with death, and mystical transformations typically come unbidden; in contrast, psychoactive substances—though not entirely predictable—are more consistently available and can be managed safely. Koch’s book implies that there’s immense psychological benefit of entering "the flow" through chemistry that might outweigh the small risks involved.
Overall, Then I Am Myself the World is a smoothly written must-read for anyone interested in a detailed introduction to the relationship between the brain, consciousness, and transformative experiences. However, it also bears witness to Koch’s personal journey from a neuroscientist studying the tangible elements of brain states to a man swept up by a quest to expand and transform his own life experiences. As a reader, one can’t help but identify with Koch’s drive to live life to its fullest—ultimately, this is a human quest. Then I Am Myself the World is, at its heart, a cogent reminder to cherish our own conscious experiences while we have the power to do so.
Lindsey Laughlin is a science writer and freelance journalist who lives in Portland, Oregon, with her husband and four children. She earned her BS from UC Davis with majors in physics, neuroscience, and philosophy.
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意識先於生命-S. Hameroff等
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依照作者群的邏輯，或許「意識先於宇宙」，以及「意識是大爆炸的根本原因」這兩個命題，應該也有三分可信度。我所說的「邏輯」，各位可以比較原文標題和其中兩句話後看出我的意思：
1) 原文標題：”Consciousness came before life”；在文法上，過去式表示動作「已完成」。
2) “We don’t yet know what consciousness is,…, so the possibility that conscious feelings existed before life cannot be excluded.”；換句話說，只要承認「無知」，一切都有可能。
3) “Of course, we cannot test for signs of consciousness, which is private and unobservable.”；如果「一個人還不知道『意識』是什麼」，那她/他憑「什麼」認為它具有這個(private)或那個(unobservable)性質。
下文其它部份的論述過於高深，我就不給別人打我臉的機會了。
Consciousness came before life
The fundamental cause of evolution
05/08/24
Stuart Hameroff |Professor of Astrobiology, Psychology and Anesthesiology, and Director of the Center for Consciousness Studies at The University of Arizona, Tucson, Arizona.
Anirban Bandyopadhyay | Principal Research Scientist at the National Institute for Materials Science (NIMS) in Tsukuba, Japan.
Dante Lauretta | Regents Professor of Planetary Science and Cosmochemistry, and Director of the Arizona Astrobiology Center, The University of Arizona, Tucson, Arizona. He led NASA’s OSIRIS REx mission to Asteroid Bennu.
Most scientists believe that consciousness came after life, as a product of evolution. But observations of extraterrestrial organic material, along with Roger Penrose and Stuart Hameroff’s quantum theory of consciousness, provide reason to believe that consciousness came before life. In fact, argue Hameroff and his collaborators, consciousness may have been what made evolution and life possible in the first place.
Most scientists and philosophers believe that life came before consciousness. Life appeared on Earth about 3.8 billion years ago; consciousness and feelings, it’s said, evolved later due to complex biological information processing, perhaps only recently in brains with language and tool-making abilities. In fact, though, there’s good reason to think that consciousness preceded life, and was central to making life and evolution possible.
What is life? It is often described as its functions: metabolism, adaptation, reproduction, etc. But non-biological systems can have similar functions, for example, oceanic hydrothermal vents can metabolize, transform energy and synthesize chemicals, weather and climate systems adapt to changes in solar radiation, volcanic activity, and other natural factors, and a seed crystal in a solution can lead to the formation of more crystals with the same lattice structure, essentially reproducing itself. In the 19th century “vitalists” proposed life was a living field, force, or élan vital, but vitalism was eclipsed by molecular biology and genetics.
Erwin Schrödinger suggested that a form of “quantum vitalism” accounted for life’s unitary oneness, and Herbert Fröhlich later proposed that quantum coherent vibrational modes, similar to those in a laser, could play a central role in various biological processes (“Fröhlich coherence”). The idea is that in a crystal-like structure, laser-like coherent vibrations could be driven by small random changes in temperature or energy.
This was proven by Anirban Bandyopadhyay’s group for biological microtubules – self-assembling cylindrical lattice polymers of the protein tubulin. Microtubules dynamically organize the interiors of all animal and plant cells, as part of the cell’s structural cytoskeleton, and appear also to serve as its nervous system and memory bank.
Anirban’s team sent low-power electromagnetic signals of varying frequency into microtubules and measured their conductance. They found distinctive self-similar resonance conductance patterns where each conductance response is grouped into sets of three, and then these groups are themselves grouped into larger sets of three. These “triplets-of-triplets” repeat in microtubules every three orders of magnitude, in kilohertz, megahertz, gigahertz and terahertz.
The “triplets-of-triplets” are phase shifted to make a unique structure called a “time crystal” (first described for biology by Arthur Winfree in the 1960s). In ordinary crystals, like salt or quartz, atoms are arranged in a repeating spatial pattern. But in a time crystal patterns also repeat in time, in a regular, repeating cycle returning to the same positions over and over. This movement happens without using energy – it's a stable, perpetual motion at the atomic level.
Microtubules are biologic time crystals that enable living systems to operate coherently over many orders of spatiotemporal scale. Microtubule vibrations emanate within each tubulin from aromatic organic molecules (rings that are made up of carbon atoms arranged in a closed loop with clouds of delocalized ‘pi resonance’ electrons). Simpler versions of these coherent oscillations, their resonance across frequencies, and time crystal behavior in early molecular systems may be considered putative “signs of life.”
What is consciousness? Many scientists view it as an emergent property of complex biological computation among simple brain neurons. But if so, how do we account for eons of purposeful behavior by earlier, simpler creatures, long before brains or genes? Animal behavior is driven by “reward,” which is made up of pleasurable feelings. Could feelings have been motivation for life right from its start?
We don’t yet know what consciousness is, nor what role it plays in the universe, so the possibility that conscious feelings existed before life cannot be excluded. Of course, we cannot test for signs of consciousness, which is private and unobservable. But anesthesia is selective, blocking consciousness while affecting very little else. We can therefore test molecular systems for what goes away under anesthesia. Furthermore, we have a plausible scientific story about what consciousness might be, which implies that conscious feelings did exist before life. Let’s look at that story now.
Penrose’s quantum consciousness
According to the physicist and Nobel laureate Sir Roger Penrose, quantum mechanics contains the key to consciousness. Quantum particles can exist in multiple wave-like possibilities simultaneously (“quantum superposition”), described by a wavefunction. In a nutshell, Penrose argues that consciousness is made of collapses of quantum superpositions into definite states.
Imagine a spinning coin that can land either heads or tails. In the quantum world it could land and exist simultaneously as both heads and tails in two locations, when no one was looking. However, when a conscious human observes the superposition, the coin is seen to have landed on either heads or tails in one position – the wavefunction has collapsed into one of the two possibilities.
For Penrose, such collapses, or “quantum state reductions,” occur spontaneously and ubiquitously in the random microenvironment due to an objective threshold, (objective reduction, OR). Moreover, OR events in the random microenvironment are predicted to be, or cause, “proto-conscious” moments, available to then be orchestrated and optimized in biological systems.
Penrose’s proposal is a novel answer to the “Measurement Problem” – the problem of explaining why we can never measure quantum superpositions because the very act of doing so seems to collapse them into definite states. The quantum pioneers John von Neumann and Eugene Wigner earlier suggested that the act of conscious observation causes quantum collapse, so that “consciousness collapses the wavefunction.” But although this interpretation still has some supporters (including Henry Stapp and David Chalmers), it cannot explain consciousness itself, and nor can it explain how quantum superposition is possible.
Penrose reverses von Neumann and Wigner’s interpretation. For Penrose, it’s not that consciousness causes the collapse of the wavefunction, but that the collapse of the wavefunction causes (or, perhaps, is) consciousness. This suggests the beginnings of an explanation of consciousness, but it raises the question: what collapses the wavefunction, if not consciousness?
To answer this question, Penrose first tries to explain the nature of superposition. How can a single particle exist in multiple states simultaneously? Here Penrose applies Einstein’s theory of general relativity (in which matter and gravity are equivalent to curvature in spacetime geometry) to tiny quantum particles with tiny spacetime curvatures. Superposition of a single particle in two locations could then be seen as two opposing curvatures in spacetime – a blister or separation in the fabric of reality at the most fundamental Planck scale, 10-33 cm.
Now Penrose can explain what collapses the wavefunction. He suggests that spacetime separations are unstable and undergo spontaneous objective reduction (OR) due to a threshold related to fundamental spacetime geometry at times t= ħ/EG. This is a form of the uncertainty principle, where ħ is the Planck-Dirac constant and EG represents the gravitational self-energy of spacetime separation. This is the energy required to separate an object (or its equivalent spacetime curvature) from itself. When the threshold is reached, separation/superposition terminate, and an OR event occurs which selects a single local reality, collapsing the short-lived beginnings of multiple, separated universes into one.
This alone is significant, but Penrose goes further, reaching for an explanation of consciousness. He supports his claim that consciousness is caused by or made up of waveform collapses by appealing to Gödel’s Incompleteness Theorem. This states that within a sufficiently complex formal system, there are always true statements that cannot be proven within that system – they are “non-computable.” We call these statements the Gödel sentences of the system; an “external determinant,” or a more powerful system, is required to prove a system’s Gödel sentences.
Penrose argues that conscious minds are not like these complex formal systems, since they don’t have any Gödel sentences. Put differently, consciousness involves a non-computable process – a process which cannot be classically computed. In contrast, familiar, classical reality is algorithmic and “computable.” Penrose therefore concludes that the non-computable process and its attendant conscious “feelings” or “qualia” must come from outside classical physics, namely from quantum physics with its own set of laws.
Although the quantum processes are non-computable and non-algorithmic, their selections are not random, according to Penrose. Rather, they are influenced by “Platonic values” intrinsic to spacetime geometry. Penrose proposed that each OR event marked a moment of phenomenal awareness – a fundamental unit of conscious experience. His picture thus provides the beginnings of explanations of quantum superposition, wavefunction collapse, and consciousness itself.
Penrose’s OR events would have been happening at the level of spacetime geometry in the microenvironment since the early universe – long before life arose. The qualia would presumably be random, disconnected, and lacking context. Penrose thus calls them “proto-conscious.” However, occasionally proto-conscious OR events would be pleasurable, and occur in molecules which could stabilize, resonate, desire and rearrange for more pleasure, prompting the origin and evolution of life.
Life and proto-consciousness in the primordial soup
How might proto-conscious OR events give rise to life? Life on earth is envisioned to have begun in a “primordial soup” – an oily froth of liquid and nutrients with occasional energy inputs. Simulations of this primordial soup in the 1950s found “amphipathic” molecules, which have sweet-smelling, oil-like (“aromatic”) rings on one end, and water-soluble structures on the other.
The aromatic rings are the basis for organic chemistry – the chemistry of life – due largely to clouds of delocalized “pi resonance” electrons, which envelop hydrocarbon rings and have quantum interactions with neighboring rings in quantum-friendly regions where photons can be absorbed, re-emitted (fluorescence), couple to mechanical vibrations (optical phonons), electricity (excitons), and enhanced light emission (super-radiance). Regions of aromatic rings inside certain brain proteins, friendly to quantum effects, are where anesthetics act to selectively block consciousness. Aromatic rings are also central to many psychoactive compounds including dopamine, serotonin, LSD and DMT .
In the ancient primordial soup, amphipathic molecules are thought to have formed soap molecule-like “micelles,” which envelope the insoluble, oil-like aromatic rings. These micelles were theorized by Alexander Oparin to have become biological “proto-cells,” developed behaviors for survival, and then become cells and organisms. But why would this have happened, long before genes and brains? What would motivate simple creatures’ purposeful behavior to survive?
Consider the following scenario, which contains a possible answer. In the primordial soup, quantum-coupled, entangled aromatic rings in superposition within micelles could have reached threshold for Penrose OR at times t=ħ/EG, resulting in sequences of random, disconnected proto-conscious moments. Some of these would exhibit positive reinforcement, a primitive form of pleasure. Thus, this mechanism could have served as a feedback fitness function for aromatic rings on amphipathic molecules to arrange within micelles for OR events which increase pleasure and avoid displeasure. Thus, the origin of life may have been prompted and driven by conscious feelings right from the start. Evolution may have worked to optimize, organize, and prioritize more advanced conscious experience involving memory, belief, forecasting, intention and iteration, driven by primitive, and then more advanced forms of pleasure-seeking. Life became the vehicle for consciousness.
How could we possibly find out whether something like this story is correct? The key might lie in the asteroids, ancient relics from the very dawn of the solar system.
Searching for extraterrestrial “signs of life” and “roots of consciousness”
The first section of this article suggested that we might consider collective coherent oscillations and other features as putative “signs of life.” Recent Japanese and US missions to near-Earth asteroids Ryugu and Bennu have returned with organic-rich materials, including some spherical structures reminiscent of micelles, called organic nanoglobules. These come in various forms, some of which involve aromatic molecules arranged in complex patterns with a range of textures and compositions.
We are studying the samples from the recent NASA mission to near-Earth asteroid Bennu led by Dante Lauretta and intend to study PAHs and especially nanoglobules for putative “signs of life.” These would be in the form of:
1) coherent oscillations among aromatic rings
2) cross-frequency phase coupling and resonance, like music
3) quantum optical fluorescence with phonon vibrations
4) time crystal behavior, e.g. repeating “triplets-of-triplets” at different scales
5) entanglement between separated aromatic rings
6) psychopharmacological effects of extraterrestrial poly-aromatic hydrocarbons, e.g. in cerebral organoids
7) self-replication and/or self-assembly
8) interaction with genetic material (RNA).
We will pay special attention to nanoglobules with complex patterns of aromatic materials, which could conceivably be akin to the micelles that Oparin thought were the starting point for life. Initially at least we will study intact nanoglobules “noninvasively” with quantum tunnelling and cloaking.
In preparation to analyze samples from Bennu we have revisited a well-studied polyaromatic molecule retrieved from the Murchison meteorite which fell in Australia in 1969. It is known as “Murchison Insoluble Organic Material Molecule” (M-IOM-M) and has numerous clusters of polyaromatic rings in a branching network, usually shown in two dimensions. Meteorite samples carry possible earthly contaminants, but this type of molecule has not been seen on earth, and similar molecules are apparent in the Bennu samples.
In three-dimensional energy minimization simulation, M-IOM-M folds into a two-nanometer, cigar-shaped dimer. Simulation of numerous such dimers showed they self-assemble into linear filaments, and numerous filaments align in parallel in a slight offset lattice, which curves into a cylinder, resembling a microtubule. Molecular dynamics simulation of M-IOM-M show time crystal behavior, with “triplets of triplets” petahertz oscillations, and binding to RNA. Thus four putative signs of life (numbers 1, 4, 7 and 8 above) were observed in simulation of M-IOM-M.These analyses will be carried out with actual experiments on PAHs and nanoglobules from Bennu. If the simulation results are confirmed, standard evolution “life-came-first” theories will be challenged.
What about consciousness? Penrose OR is the most specific scientific proposal for consciousness but is difficult to detect. However, some “signs of life” are pre-conditions for OR and could be detected, e.g. coherent oscillations, quantum optical superposition effects and triplets-of-triplets. If we find such signs of life in a sample, we will expose them to anesthetic gas to see if they are inhibited proportional to anesthetic potency in blocking consciousness in animals and humans. If so, these processes may be considered putative “roots of consciousness.”
In this way, we hope to dig deeper into the role and place of both life and consciousness in the universe. Our strategy depends on the idea of Penrose OR. This is controversial, both as a solution to the quantum measurement problem and as the source of consciousness. But Penrose OR is testable, profound, more sensible than alternatives, and comes from one of the truly great minds of these past two centuries. Occam’s razor would surely favor one grand solution to three great mysteries. Why couldn’t Penrose OR be the solution to the quantum measurement problem, consciousness, and the “spark of life”? If it is, then consciousness has to be seen as fundamental – not a consequence of evolution, but a prerequisite for it.
Acknowledgements: We thank Sir Roger Penrose and Eugene Jhong
You can see Stuart Hameroff live, debating in ‘’ alongside biologist Denis Noble and philosopher Antonella Tramacere at the upcoming HowTheLightGetsIn Festival on May 24th-27th.
This article is presented in partnership with Closer To Truth, an esteemed partner for the 2024 HowTheLightGetsIn Hay Festival. Dive deeper into the profound questions of the universe with thousands of video interviews, essays, and full episodes of the long-running TV show at their website: www.closertotruth.com.
References
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Everett H (1957). Relative state formulation of quantum. Mech. Rev. Modern Phys. 29, 454–462. doi: 10.1103/revmodphys.29.454
Fröhlich H (1970) Long range coherence and the actions of enzymes. Nature 228:1093. doi: 10.1038/2281093a0
Hameroff S (2017) The quantum origin of life: how the brain evolved to feel good, in On Human Nature eds M Tibayrenc and FJ Ayala (Elsevier 333–353).
Hameroff S, Penrose R (1996a) Orchestrated reduction of quantum coherence in brain microtubules. Math. Comput. Simul. 40, 453–480. doi: 10.1016/0378-4754(96)80476-9
Hameroff S, Penrose, R. (1996b). Conscious events as orchestrated space–time selections. J. Conscious. Stud. 3, 36–53.
Hameroff S, Penrose R (2014) Consciousness in the universe: a review of the ‘Orch OR’ theory. Phys. Life Rev. 11, 39–78.
Hameroff S, Watt RC (1982) Information processing in microtubules. J. Theor. Biol. 98, 549–561. doi: 10.1016/0022-5193(82)90137-0
Lauretta D et al (2017) OSIRIS-REx: sample return from asteroid (101955) Bennu. Space Science Reviews 212 (2017): 925-984.
Lazcano Antonio (2016) Alexandr I. Oparin and the origin of life: a historical reassessment of the heterotrophic theory. Journal of Molecular Evolution 83: 214-222.
Lauretta D (2024) The Asteroid Hunter, Grand Central Publications
Pathak AK, Hameroff S, Ghosh S, Lauretta D, Bandyopadhyay A (2024) “Signs of Life in Murchison IOM Molecule (M-IOM-M): “Triplets of Triplets” Poster Presentation at Arizona Astrobiology Center Poster Forum, May 3, 2024 https://static.uahirise.org/aabc/pathak-hameroff-may-24.pdf
Penrose R (1989) The Emperor’s New Mind, Oxford: Oxford Univ. Press.
Penrose, R. (2022) New physics for the Orch OR consciousness proposal, in Consciousness and Quantum Mechanics, ed. S. Gao (Oxford: Oxford Press).
Sahu et al ,(2013a) Atomic water channel controlling remarkable properties of a single brain microtubule: correlating single protein to its supramolecular assembly. Biosens. Bioelectron. 47, 141–148. doi: 10.1016/j.bios.2013.02.050
Saxena K et al (2020) Fractal, scale free electromagnetic resonance of a single brain extracted microtubule, a single tubulin protein and a single neuron. Fractal Fractional 4:12. doi: 10.3390/fractalfract4020011
Schrödinger, E. (1944). What is Life? Cambridge, MA: Cambridge University Press.
Singh P et al (2021) Electrophysiology using coaxial atom probe array: live imaging reveals hidden circuits of a hippocampal neural network. J. Neurophysiol. 125, 2107–2116. doi: 10.1152/jn.00478.2020
von Neumann, J (1955) Mathematical foundations of quantum mechanics." (1955).
Wigner EP (1961) Remarks on the mind–body question. In (IJ Good, ed.) The Scientist Speculates.
Winfree AT (2010) The Geometry of Biological Time, Springer
Pathak et al, 2024: https://static.uahirise.org/aabc/pathak-hameroff-may-24.pdf
You can see Stuart Hameroff live, debating in ‘’ alongside biologist Denis Noble and philosopher Antonella Tramacere at the upcoming HowTheLightGetsIn Festival on May 24th-27th in Hay-on-Wye.
This article is presented in association with Closer To Truth, an esteemed partner for the 2024 HowTheLightGetsIn Festival.
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「什麼才算是意識？」對談 – Dan Falk/ Christof Koch
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索引：
causal powers：因果能力(採取行動並導致某種結果的能力)
goo：有粘黏性的東西
gradient：(不同)程度的，坡度，傾斜度
imbued：灌輸，使充滿，使滲透，深深影響
LLM：large language model；大型語言模型
neuromorphic engineering：神經形態計算工程：以人腦結構與功能為範例的電腦計算方式
woo-woo：假的，不科學的，想像出來的，空穴來風的，無憑無據的
英文解釋：
Derogatory/Informal
noun – unconventional beliefs regarded as having little or no scientific basis, especially those relating to spirituality, mysticism, or alternative medicine. "some kind of metaphysical woo-woo"
adjective -- relating to or holding unconventional beliefs regarded as having little or no scientific basis, especially those relating to spirituality, mysticism, or alternative medicine. "quartz crystals that were so popular with the woo-woo crowd"
What Counts as Consciousness
Neuroscientist Christof Koch on human minds, AI, and bacteria.
DAN FALK, 05/06/24
Some years ago, when he was still living in southern California, neuroscientist Christof Koch drank a bottle of Barolo wine while watching The Highlander, and then, at midnight, ran up to the summit of Mount Wilson, the 5,710-foot peak that looms over Los Angeles.
After an hour of “stumbling around with my headlamp and becoming nauseated,” as he later described the incident, he realized the nighttime adventure was probably not a smart idea, and climbed back down, though not before shouting into the darkness the last line of William Ernest Henley’s 1875 poem “Invictus”: “I am the master of my fate / I am the captain of my soul.
Koch, who first rose to prominence for his collaborative work with the late Nobel Laureate Francis Crick, is hardly the only scientist to ponder the nature of the self -- but he is perhaps the most adventurous, both in body and mind. He sees consciousness as the central mystery of our universe, and is willing to explore any reasonable idea in the search for an explanation.
Over the years, Koch has toyed with a wide array of ideas, some of them distinctly speculative -- like the idea that the Internet might become conscious, for example, or that with sufficient technology, multiple brains could be fused together, linking their accompanying minds along the way. (And yet, he does have his limits: He’s deeply skeptical both of the idea that we can “upload” our minds and of the “simulation hypothesis.”)
In his new book, Then I Am Myself The World, Koch, currently the chief scientist at the Allen Institute for Brain Science in Seattle, ventures through the challenging landscape of integrated information theory (IIT), a framework that attempts to compute the amount of consciousness in a system based on the degree to which information is networked. Along the way, he struggles with what may be the most difficult question of all: How do our thoughts -- seemingly ethereal and without mass or any other physical properties -- have real-world consequences? We caught up with him recently over Zoom.
In your new book, you ask how the mind can influence matter. Are we any closer to answering that question today than when Descartes posited it nearly four centuries ago?
Let’s step back. Western philosophy of mind revolves around two poles, the physical and the mental -- think of them like the north and the south pole. There’s materialism, which is now known as physicalism, which says that only physical really exists, and there is no mental; it’s all an illusion, like Daniel Dennett and others have said.
Then there’s idealism, which is now enjoying a mini-renaissance, but by and large has not been popular in the 20th and early 21st century, which says that everything fundamentally is a manifestation of the mental.
Then there is classical dualism, which says, well, there’s clearly physical matter and there’s the mental, and they somehow have to interact. It’s been challenging to understand how the mental interacts with the physical -- that’s known as the causation problem.
And then there are other things like panpsychism, that’s now becoming very popular again, which is a very ancient faith. It says that fundamentally everything is “ensouled” -- that everything, even elementary particles, feel a little bit like something.
All of these different positions have problems. Physicalism remains a dominant philosophy, particularly in Western philosophy departments and big tech. Physicalism says that everything fundamentally is physical, and you can simulate it -- this is called “computational functionalism.” The problem is that, so far, people have been unable to explain consciousness, because it’s so different from the physical.
What does integrated information theory say about consciousness?
IIT says, fundamentally, what exists is consciousness. And consciousness is the only thing that exists for itself. You are conscious. Tonight, you’re going to go into a deep sleep at some point, and then you’re not conscious anymore; then you do not exist for yourself. Your body and your brain still have an existence for others -- I can see your body there -- but you don’t exist for yourself. So only consciousness exists for itself; that’s absolute existence. Everything else is derivative.
It says consciousness ultimately is causal power upon itself -- the ability to make a difference. And now you’re looking for a substrate -- like a brain or computer CPU or anything. Then the theory says, whatever your conscious experience is -- what it feels like to see red, or to smell Limburger cheese, or to have a particular type of toothache -- maps one-to-one onto this structure, this form, this causal relationship. It’s not a process. It’s not a computation. It’s very different from all other theories.
When you use this term “causal powers,” how is it different from an ordinary cause-and-effect chain of events? Like if you’re playing billiards, you hit the cue ball, and the cue ball hits the eight ball …
It’s nothing woo-woo. It’s the ability of a system, let’s say a billiard ball, to make a difference. In other words, if it gets hit by another ball, it moves, and that has an effect in the world.
And IIT says you have a system -- a bunch of wires or neurons -- and it’s the extent to which they have causal power upon themselves. You’re always looking for the maximum causal power that the system can have on itself. That is ultimately what consciousness is. It’s something very concrete. If you give me a mathematical description of a system, I can compute it, it’s not some ethereal thing.
So it can be objectively measured from the outside?
That’s correct.
But of course there was the letter last year that was signed by 124 scientists claiming that integrated information theory is pseudoscience, partly on the grounds, they said, that it isn’t testable.
Many years ago, I organized a meeting in Seattle, where we came together and planned an “adversarial collaboration.” It was specifically focused on consciousness. The idea was: Let’s take two theories of consciousness -- in this case, integrated information theory versus the other dominant one, global neuronal workspace theory. Let’s get people in a room to discuss -- yes, they might disagree on many things -- but can we agree on an experiment that can simultaneously test predictions from the two theories, and where we agree ahead of time, in writing: If the outcome is A it supports theory A; if it’s B, it supports theory B? It involved 14 different labs.
The experiments were trying to predict where the “neural footprints of consciousness,” crudely speaking, are. Are they in the back of the brain, as integrated information theory asserts, or in the front of the brain, as global neuronal workspace asserts? And the outcome was very clear -- two of the three experiments were clearly against the prefrontal cortex and in favor of the neural footprint of conscious being in the back.
This provoked an intense backlash in the form of this letter, where it was claimed the theory is untestable, which I think is just baloney. And then, of course, there was blowback against the blowback, because people said, wait, IIT may be wrong -- the theory is certainly very different from the dominant ideology -- but it’s certainly a scientific theory; it makes some very precise predictions.
But it has a different metaphysics. And people don’t like this.
Most people today believe that if you can simulate something, that’s all you need to do. If a computer can simulate the human brain, then of course [the simulation is] going to be conscious. And LLMs -- sooner or later [in the functionalist view] they’re going to be conscious -- it’s just a question of, is it conscious today, or do you need some more clever algorithm?
IIT says, no, it’s not about simulating; it’s not about doing -- it’s ultimately about being, and for that, really, you have to look at the hardware in order to say whether it’s conscious or not.
Does IIT involve a commitment to panpsychism?
It’s not panpsychism. Panpsychism says, “this table is conscious” or “this fork is conscious.” Panpsychism says, fundamentally, everything is imbued with both physical properties as well as mental properties. So an atom has both mental and physical properties.
IIT says, no, that’s certainly not true. Only things that have causal power upon themselves [are conscious] -- this table doesn’t have any causal power upon itself; it just doesn’t do anything, it just sits there.
But it shares some intuitions [with panpsychism] -- in particular, that conscience is on a gradient, and that maybe even a comparatively simple system, like a bacterium -- already a bacterium contains a billion proteins, [there’s] immense causal interaction -- it may well be that this little bacterium feels a little bit like something. Nothing like us, or even the consciousness of a dog. And when it dies, let’s say, when you’re given antibiotics and its membrane dissolves, then it doesn’t feel like anything anymore.
A scientific theory has to rest on its predictive power. And if the predictive power says, yes, consciousness is much wider than we think -- it’s not only us and maybe the great apes; maybe it’s throughout the animal kingdom, maybe throughout the tree of life -- well, then, so be it.
Toward the end of the book, you write, “I decide, not my neurons.” I can’t help thinking that that’s two ways of saying the same thing -- on the macro level it’s “me,” but on the micro level, it’s my neurons. Or am I missing something?
Yeah, it’s a subtle difference. What truly exists for itself is your consciousness. When you’re unconscious, as in a deep sleep or on anesthesia, you don’t exist for yourself anymore, and you’re unable to make any decisions. And so what truly exists is consciousness, and that’s where the true action happens.
I actually see you on the screen, there are lights in the image; inside my brain, I can assure you, there are no lights, it’s totally dark. My brain is just in a goo. So it’s not my brain that sees; it’s consciousness that sees. It’s not my brain that makes a decision, it’s my consciousness that makes a decision. They’re not the same.
For as long as we’ve had computers, people have argued about whether the brain is an information processor of some kind. You’ve argued that it isn’t. From that perspective, I’m guessing you don’t think large language models have causal powers.
Correct. In fact, I can pretty confidently make the following statement: There’s no Turing test for consciousness, according to IIT, because it’s not about a function; it’s all about this causal structure. So you actually have to look at the CPU or the chip -- whatever does the computation. You have to look at that level: What’s the causal power?
Now you can of course simulate perfectly well a human brain doing everything a human brain can do -- there’s no problem conceptually, at least. And of course, a computer simulation will one day say, “I’m conscious,” like many large language models do, unless they have guardrails where they explicitly tell you “Oh no, I’m just an LLM -- I’m not conscious,” because they don’t want to scare the public.
But that’s all simulation; that’s not actually being conscious. Just like you can simulate a rainstorm, but it never gets wet inside the computer, funny enough, even though it simulated a rainstorm. You can solve Einstein’s equation of general relativity for a black hole, but you never have to be afraid that you’re going to be sucked into your computer simulation. Why not? If it really computes gravity, then shouldn’t spacetime bend around my computer and suck me, and the computer, in? No, because it’s a simulation. That’s the difference between the real and the simulated. The simulated doesn’t have the same causal powers as the real.
So unless you build a machine in the image of a human brain -- let’s say using neuromorphic engineering, possibly using quantum computers -- then you can’t get human-level consciousness. If you just build them like we build them right now, where one transistor talks to two or three other transistors -- that’s radically different from the connectivity of the human brain -- you’ll never get consciousness. So I can confidently say that although LLMs very soon will be able to do everything we can do, and probably faster and better than we can do, they will never be conscious.
So in this view, it’s not “like anything” to be a large language model, whereas it might be like something to be a mouse or a lizard, for example?
Correct. It is like something to be a mouse. It’s not like anything to be an LLM -- although the LLM is vastly more intelligent, in any technical sense, than the mouse.
Yet somewhat ironically, the LLM can say “Hello there, I’m conscious,” which the mouse cannot do.
That’s why it’s so seductive, because it can speak to us, and express itself very eloquently. But it’s a gigantic vampire -- it sucks up all of human creativity, throws it into its network, and then spits it out again. There’s no one home there. It doesn’t feel like anything to be an LLM.
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眼睛錯覺可能說明「意識」如何形成 -- Emily Cooke
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此研究的重要性在於：它「證明」了，或至少「顯示」了，「意識」的形成需要根據過去的「經驗」，就大腦神經學而言，「經驗」就是「記憶」，也就是「神經細胞」構成的網絡。此所以完全失去「記憶」，也就沒有「意識」可言：這是阿茲海默症可怕之處。
Optical illusion reveals key brain rule that governs consciousness
Emily Cooke, 05/02/24
A study of mice starts to unravel how the brain gets tricked by this kind of optical illusion, and it gives clues about how visual perception works.
請至原網頁觀看和以下解說相關的圖片
The new study investigated the perception of brightness in mice by looking at how they responded to an optical illusion called the neon-color-spreading illusion, an example of which is illustrated above. (Image credit: Mabit1, CC BY-SA 4.0 DEED, via Wikimedia Commons https://creativecommons.org/licenses/by-sa/4.0/deed.en；請至原網頁查看照片)
Optical illusions play on the brain's biases, tricking it into perceiving images differently than how they really are. And now, in mice, scientists have harnessed an optical illusion to reveal hidden insights into how the brain processes visual information.
The research focused on the neon-color-spreading illusion, which incorporates patterns of thin lines on a solid background. Parts of these lines are a different color — such as lime green, in the example above — and the brain perceives these lines as part of a solid shape with a distinct border — a circle, in this case. The closed shape also appears brighter than the lines surrounding it.
It's well established that this illusion causes the human brain to falsely fill in and perceive a nonexistent outline and brightness — but there's been ongoing debate about what's going on in the brain when it happens. Now, for the first time, scientists have demonstrated that the illusion works on mice, and this allowed them to peer into the rodents' brains to see what's going on.
Specifically, they zoomed in on part of the brain called the visual cortex. When light hits our eyes, electrical signals are sent via nerves to the visual cortex. This region processes that visual data and sends it on to other areas of the brain, allowing us to perceive the world around us.
The visual cortex is made of six layers of neurons that are progressively numbered V1, V2, V3 and so on. Each layer is responsible for processing different features of images that hit the eyes, with V1 neurons handling the first and most basic layer of data, while the other layers belong to the "higher visual areas." These neurons are responsible for more complex visual processing than V1 neurons.
Until now, scientists have debated the extent to which V1 neurons respond to illusory brightness, such as the brightness people perceive when looking at the neon-color-spreading illusion. In a series of lab experiments in mice, researchers have now shown that these neurons play a fundamental role in this process and that their activity is also tempered by feedback from V2 neurons. So there's a volley back and forth between these different layers of the visual cortex.
This knowledge may bolster our understanding of consciousness, the researchers said in a paper published April 23 in the journal Nature Communications.
"The observed relationship between V1 and V2 in processing the illusion implies that consciousness is a top-down process," as opposed to a bottom-up process, co-author Masataka Watanabe, an associate professor in the department of systems innovation at the University of Tokyo, told Live Science in an email.
請至原網頁觀看和以下解說相關的圖片
This is an alternative version of the neon-color-spreading illusion. In this case, the brain perceives the colored blue lines as belonging to a blue circle, but in reality, the background is still white and the blue lines don't form a closed shape. (Image credit: blebspot, CC BY-SA 3.0 DEED, via Wikimedia Commons https://creativecommons.org/licenses/by-sa/3.0/deed.en)
Top-down processing refers to the way our brains interpret our surroundings by taking prior experiences into account, rather than solely relying on visual stimuli alone. By contrast, pure bottom-up processing would take the different features of an image and snap them together like puzzle pieces, making a coherent picture without input from a person's memory.
Other studies have implied that consciousness is a top-down-process, but this mouse study provides direct evidence for it, Watanabe said. The answer isn't black and white though, as some argue that consciousness likely arises from a mixture of both.
What is the new evidence? In the study, mice were shown a combination of neon-color-spreading illusions and other, similar-looking patterns that did not trigger the illusion. Simultaneously, Watanabe and colleagues measured the activity of neurons in the rodents' brains with implanted electrodes.
The team also measured whether the mice saw the illusions as bright by assessing how much the pupils in their eyes dilated or constricted. This response matched that seen in humans when we perceive changes in light levels.
V1 neurons respond to both illusory and non-illusory images, but they take longer to respond to the former. This supports the theory that V1 neurons need feedback from higher visual areas to process these types of illusions, the team reported.
The researchers then tried experimentally inhibiting the activity of the higher visual area neurons, finding that V1 neurons were less likely to respond to the illusions. This provided further evidence that a higher-level feedback loop is needed to perceive the illusion.
Going forward, the team plans to conduct further studies in which they'll mess with the activity of higher visual area neurons in mice, Watanabe said. They hope that this will shed more light on the neural mechanisms underlying consciousness in mice, and by extension, in humans.
Related:
The brain-bending secret behind hundreds of optical illusions has finally been revealed
Super-detailed map of brain cells that keep us awake could improve our understanding of consciousness
How this trippy illusion will make you see an 'expanding black hole'
This optical illusion tricks you into seeing different colors. How does it work?
A new type of optical illusion tricks the brain into seeing dazzling rays
Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!
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意識脈絡圖 -- Noa Leach
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在我看來，下文所報導科學研究論文的作者群不無「一廂情願」之嫌(wishful thinking)。
New ‘map of consciousness’ could help to wake up coma patients
Scientists may finally have cracked the code of what makes us experience consciousness.
Image credit: Getty (請至原網頁觀看照片)
Noa Leach, 05/02/24
Despite being a fundamental part of human existence, we know very little about consciousness and how it happens. Now, scientists have just brought us one step closer to finding out with a new 'map of consciousness' – and their results could help to wake up coma patients.
Human consciousness is made from two crucial building blocks: arousal and awareness. In a groundbreaking new study, published in the journal Science Translational Medicine, a team of scientists have mapped out how these two states join up.
The result? A ‘map of wakefulness’ that charts the connectivity of the brain and reveals where consciousness takes place.
Using MRI scans, the researchers from Massachusetts General Hospital and Boston Children’s Hospital were able to study three post-mortem human brains at resolutions of less than a millimetre.
The map revealed previously unseen pathways between key areas of the brain. When joined together, the researchers called these pathways the ‘default network’ of the brain. This, they say, is the part of your brain that is active during a resting state of consciousness.
Just like when you plan your route to a destination, the researchers also used the map to work out the ‘route’ that is vital to firing up self-awareness.
請至原網頁觀看和以下解說相關的圖片
In the top panel, the red and blue tracts show where scientists previously thought consciousness came from, based on animal studies from the mid-20th Century. These tracts come from the midbrain and pontine reticular formations, respectively. But the pink and yellow tracts in the bottom panel come from additional 'extrareticular' brainstem nuclei that scientists now believe contribute to wakefulness in the human brain. - Image credit: Edlow et al., Sci. Trans. Med., 16 eadj4303 (2024).
“Our goal was to map a human brain network that is critical to consciousness and to provide clinicians with better tools to detect, predict, and promote recovery of consciousness in patients with severe brain injuries,” said lead author and Harvard University associate professor Brian Edlow.
These brain injuries include those that lead to comas. In fact, the researchers think these findings could even help patients recover from comas – highlighting key sites where stimulation could ‘wake up’ connections with other regions of the brain that are critical to consciousness.
The authors are currently conducting clinical trials to see if they can reactivate the default network and restore consciousness in coma patients.
According to senior author Hannah Kinney, the results themselves could be used as their own kind of map “to better understand a broad range of neurological disorders associated with altered consciousness”.
Read more:
* ‘A pivotal moment in neuroscience’: Scientists finally discover the brain cells that make you unique
* Eight ways to sharpen your mind and tune up your brain Eight ways to sharpen your mind and tune up your brain
* This new ‘atlas of ageing’ could help keep your muscles younger for longer
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大腦神經學入門-Susan Hillier
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Alpha, beta, theta: what are brain states and brain waves? And can we control them?
Susan Hillier, 12/22/23
There’s no shortage of apps and technology that claim to shift the brain into a “theta” state – said to help with relaxation, inward focus and sleep.
But what exactly does it mean to change one’s “mental state”? And is that even possible? For now, the evidence remains murky. But our understanding of the brain is growing exponentially as our methods of investigation improve.
Brain-measuring tech is evolving
Currently, no single approach to imaging or measuring brain activity gives us the whole picture. What we “see” in the brain depends on which tool we use to “look”. There are myriad ways to do this, but each one comes with trade-offs.
We learnt a lot about brain activity in the 1980s thanks to the advent of magnetic resonance imaging (MRI).
Eventually we invented “functional MRI”, which allows us to link brain activity with certain functions or behaviours in real time by measuring the brain’s use of oxygenated blood during a task.
We can also measure electrical activity using EEG (electroencephalography). This can accurately measure the timing of brain waves as they occur, but isn’t very accurate at identifying which specific areas of the brain they occur in.
Alternatively, we can measure the brain’s response to magnetic stimulation. This is very accurate in terms of area and timing, but only as long as it’s close to the surface.
What are brain states?
All of our simple and complex behaviours, as well as our cognition (thoughts) have a foundation in brain activity, or “neural activity”. Neurons – the brain’s nerve cells – communicate by a sequence of electrical impulses and chemical signals called “neurotransmitters”.
Neurons are very greedy for fuel from the blood and require a lot of support from companion cells. Hence, a lot of measurement of the site, amount and timing of brain activity is done via measuring electrical activity, neurotransmitter levels or blood flow.
We can consider this activity at three levels. The first is a single-cell level, wherein individual neurons communicate. But measurement at this level is difficult (laboratory-based) and provides a limited picture.
As such, we rely more on measurements done on a network level, where a series of neurons or networks are activated. Or, we measure whole-of-brain activity patterns which can incorporate one or more so-called “brain states”.
According to a recent definition, brain states are “recurring activity patterns distributed across the brain that emerge from physiological or cognitive processes”. These states are functionally relevant, which means they are related to behaviour.
Brain states involve the synchronisation of different brain regions, something that’s been most readily observed in animal models, usually rodents. Only now are we starting to see some evidence in human studies.
Various kinds of states
The most commonly-studied brain states in both rodents and humans are states of “arousal” and “resting”. You can picture these as various levels of alertness.
Studies show environmental factors and activity influence our brain states. Activities or environments with high cognitive demands drive “attentional” brain states (so-called task-induced brain states) with increased connectivity. Examples of task-induced brain states include complex behaviours such as reward anticipation, mood, hunger and so on.
In contrast, a brain state such as “mind-wandering” seems to be divorced from one’s environment and tasks. Dropping into daydreaming is, by definition, without connection to the real world.
We can’t currently disentangle multiple “states” that exist in the brain at any given time and place. As mentioned earlier, this is because of the trade-offs that come with recording spatial (brain region) versus temporal (timing) brain activity.
Brain states vs brain waves
Brain state work can be couched in terms such as alpha, delta and so forth. However, this is actually referring to brain waves which specifically come from measuring brain activity using EEG.
EEG picks up on changing electrical activity in the brain, which can be sorted into different frequencies (based on wavelength). Classically, these frequencies have had specific associations:
* gamma is linked with states or tasks that require more focused concentration
* beta is linked with higher anxiety and more active states, with attention often directed externally
* alpha is linked with being very relaxed, and passive attention (such as listening quietly but not engaging)
* theta is linked with deep relaxation and inward focus
* and delta is linked with deep sleep.
Brain wave patterns are used a lot to monitor sleep stages. When we fall asleep we go from drowsy, light attention that’s easily roused (alpha), to being relaxed and no longer alert (theta), to being deeply asleep (delta).
Brainwaves are grouped into five different wavelength categories. Shutterstock (請至原網頁查看人類腦波頻率分佈圖)
Can we control our brain states?
The question on many people’s minds is: can we judiciously and intentionally influence our brain states?
For now, it’s likely too simplistic to suggest we can do this, as the actual mechanisms that influence brain states remain hard to detangle. Nonetheless, researchers are investigating everything from the use of drugs, to environmental cues, to practising mindfulness, meditation and sensory manipulation.
Controversially, brain wave patterns are used in something called “neurofeedback” therapy. In these treatments, people are given feedback (such as visual or auditory) based on their brain wave activity and are then tasked with trying to maintain or change it. To stay in a required state they may be encouraged to control their thoughts, relax, or breathe in certain ways.
The applications of this work are predominantly around mental health, including for individuals who have experienced trauma, or who have difficulty self-regulating – which may manifest as poor attention or emotional turbulence.
However, although these techniques have intuitive appeal, they don’t account for the issue of multiple brain states being present at any given time. Overall, clinical studies have been largely inconclusive, and proponents of neurofeedback therapy remain frustrated by a lack of orthodox support.
Other forms of neurofeedback are delivered by MRI-generated data. Participants engaging in mental tasks are given signals based on their neural activity, which they use to try and “up-regulate” (activate) regions of the brain involved in positive emotions. This could, for instance, be useful for helping people with depression.
Another potential method claimed to purportedly change brain states involves different sensory inputs. Binaural beats are perhaps the most popular example, wherein two different wavelengths of sound are played in each ear. But the evidence for such techniques is similarly mixed.
Treatments such as neurofeedback therapy are often very costly, and their success likely relies as much on the therapeutic relationship than the actual therapy.
On the bright side, there’s no evidence these treatment do any harm – other than potentially delaying treatments which have been proven to be beneficial.
Susan Hillier Professor: Neuroscience and Rehabilitation, University of South Australia
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意識的存在不需要一個「自己」 -- James Cooke
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Consciousness does not require a self
The self is a prediction of the brain
James Cooke, 12/14/23
The idea that consciousness requires a self has been around since at least Descartes. But problems of infinite regress, neuroscientific studies, and psychedelic experiences point to a different reality. 'You' may not be what you seem to be, writes James Cooke.
We typically feel like we are the conscious subject, the one who has experiences. Look around you in this moment and direct your attention to different objects. It can feel like we exist in our heads, behind our eyes, directing a spotlight of attention in order to wilfully make things conscious. This intuitive model of the mind has often been imported into the science and philosophy of consciousness, leading to confusion in our understanding of the true nature of experience. This subject is not the bodily organism, it is something that is felt to live inside us, the possessor of the body, the “you” that is reading these words now. Consciousness is very much a property of the bodily subject, but not of the conscious subject that is felt to live in our heads.
Thinking in terms of conscious subjects was present at the very origins of the scientific method, in the work of Rene Descartes. Descartes saw the natural world as unconscious mechanism. Humans alone were conceived of as being conscious by virtue of a transcendent subject that could illuminate our experience of the world [1]. If we want to understand consciousness, however, postulating the existence of an inherently conscious subject merely passes the buck of explanation. What makes that conscious subject conscious? If it is intrinsically conscious then consciousness has not been explained. If not, then what makes it conscious, another subject within it? With this logic we end up in an infinite regress, with consciousness never being explained. This view of the mind has been dubbed the Cartesian Theatre by philosopher Daniel Dennett [2].
Many scientific accounts of consciousness too appeal to a self-like mechanism in the brain that is responsible for bestowing the illuminating quality of consciousness on the informational content processed by the brain [3]. The brain is a hierarchically structured network, with sensory information entering the brain at the bottom of this hierarchy and subsequently passing through multiple layers of processing. In contrast to the lower levels which analyse sensory information, the top levels deal with cognitive tasks such as decision making and the directing of attention. Some theories hold consciousness to arise in a bottom-up manner, passively bubbling up out of the information-processing performed by the brain. Subject-based theories, on the other hand, see consciousness as a top-down phenomenon, something that occurs as the result of active introspection performed by high-level brain regions [4]. The brain is organised so that sensory information is predominantly processed in the posterior half of the brain, while executive functions such as decision-making and attention largely rely on brain areas in the front half of the brain. Neural correlates of consciousness have been observed in both posterior and anterior brain regions, lending credence to both the bottom up and top down perspectives [5].
There’s one issue, however, the fact that frontal areas of the brain are recruited by the act of communication. When the subject in an experiment reports what it is that they are consciously perceiving, we cannot tell if the frontal brain activity is due to it playing a role in consciousness itself or merely the act of reporting on the contents of consciousness. One study found a clever way around this, by deciphering what subjects were experiencing based on physiological data, such as pupil dilation. When the subjects didn’t have to report the contents of consciousness, the frontal correlates diminished [6]. The neural structures we associate with the idea of the introspecting subject seem to not underpin consciousness itself after all, but to instead merely report on the contents of consciousness.
Beyond the neuroscientific study of consciousness, phenomenological analysis also reveals the self to not be the possessor of experience. In mystical experiences induced by meditation or psychedelics, individuals typically enter a mode of experience in which the psychological self is absent, yet consciousness remains [7]. While this is not the default state of the mind, the presence of consciousness in the absence of a self shows that consciousness is not dependent on an experiencing subject. What is consciousness if not a capacity of an experiencing subject? Such an experience reveals consciousness to consist of a formless awareness at its core, an empty space in which experience arises, including the experience of being a self [8]. The self does not possess consciousness, consciousness is the experiential space in which the image of a psychological self can appear. This mode of experience can be challenging to conceptualise but is very simple when experienced – it is a state of simple appearances arising without the extra add-on of a psychological self inspecting them.
We can think of a conscious system as a system that is capable of holding beliefs about the qualitative character of the world. We should not think of belief here as referring to complex conceptual beliefs, such as believing that Paris is the capital of France, but as the simple ability to hold that the world is a certain way. You do this when you visually perceive a red apple in front of you, the experience is one of believing the apple to exist with all of its qualities such as roundness and redness. This way of thinking is in line with the work of Immanuel Kant, who argued that we never come to know reality as it is but instead only experience phenomenal representations of reality [9]. We are not conscious of the world as it is, but as we believe it to be.
There is a branch of mathematics that deals with how we optimally update our beliefs in light of new evidence, known as Bayesian inference. One issue with seeing the brain as performing Bayesian inference is that this process involves knowing the probability of all possible causes that could have given rise to any piece of evidence, information the brain could not possibly have access to. A workaround has been found in the strategy of “free energy minimization”, in which the brain starts with a guess about the causes of sensory inputs and updates it in light of how surprising the evidence it receives would be if that belief were true [10]. With this approach, this initial belief is successfully sculpted to align with reality, with no need to know all of the possible causes behind any piece of evidence. This dynamic is described in Karl Frison’s Free Energy Principle (FEP), and it goes a long way to account for how the contents of consciousness are shaped by the sensory inputs the brain receives, as well as by the prior beliefs that it holds [11].
The FEP does not just explain how the beliefs that underlie our perception of the world become shaped, but it also accounts for how it is that we come to act in the world [12]. In this framework, known as active inference, a belief is initially formed about the world being in a state that is different to its current state. Say you are sitting down and want to stand up. The brain creates the belief that you are standing up and then your body moves in whatever way is necessary to reduce the surprising feedback it receives, given that you are not currently in that state. The end result is that you move towards the goal of standing via an optimal trajectory. In his “Beast Machine” theory of selfhood, Anil Seth suggests that the experience of the subject is a Bayesian belief of this kind [13]. The belief in an unchanging self that continues over time becomes a self-fulfilling prophecy as a result of this process of prediction-error minimization, under the active inference framework. We come to act like a coherent bodily self over time because we have the belief that we are a stable unitary self. We perceive ourselves into existence.
If consciousness is thought to depend on complex cognitive machinery that allows for the construction of a psychological self that can introspect, we can flatter ourselves with the impression that only we, and complex creatures sufficiently like us, are conscious. If this is not the case, however, and consciousness is something less complex yet more fundamental than the self, we are faced with the possibility that experience may exist more widely than is commonly thought. By getting rid of the subject, we can see consciousness to not be the product of sophisticated brains that can introspect on experience but instead as the fundamental ability to know the world that all organisms possess.
Belief updating does not just happen in brains, it is a fundamental aspect of being alive. We typically dismiss the possibility of organisms without nervous systems as being conscious because of the widespread belief that they can function by unconscious reflex alone. This idea is a myth that contravenes our understanding of the thermodynamics of life. In order to survive over time, we need to construct beliefs about the world so that we can successfully navigate it. The FEP not only provides a strategy by which brains can perform approximate Bayesian inference, it also shows that such a strategy is necessary for any living system that can keep itself orderly over time [14].
In this view, consciousness does not require a complex brain that can construct a self with the power to make the contents of the mind conscious. Consciousness is instead seen as the attempt to know the world that all living things must engage in, in order to exist over time. In this way, we can see consciousness as existing in the way that the organism interacts with the world, as a process or behaviour rather than as a “thing”. From this perspective, the space of awareness that exists prior to the experience of the self can be conceived of as what Thomas Metzinger has called an “epistemic space”, the space in which beliefs about both the character of the world and the self can arise [15]. By understanding consciousness to exist prior to the experience of psychological selfhood, we can both remove a major roadblock to the scientific understanding of consciousness and come to know the nature of our own minds more fully.
References:
[1] Descartes, R. (2013). Meditations on first philosophy. Broadview Press.
[2] Dennett, D. C., & Kinsbourne, M. (1992). Escape from the Cartesian theater. Behavioral and Brain Sciences, 15(2), 234-247.
[3] Seth, A. K., & Bayne, T. (2022). Theories of consciousness. Nature Reviews Neuroscience, 23(7), 439-452.
[4] Lau, H., & Rosenthal, D. (2011). Empirical support for higher-order theories of conscious awareness. Trends in cognitive sciences, 15(8), 365-373.
[5] Koch, C., Massimini, M., Boly, M., & Tononi, G. (2016). Neural correlates of consciousness: progress and problems. Nature Reviews Neurosciene
[6] Frässle, S., Sommer, J., Jansen, A., Naber, M., & Einhäuser, W. (2014). Binocular rivalry: frontal activity relates to introspection and action but not to perception. Journal of Neuroscience, 34(5), 1738-1747.
[7] Millière, R., Carhart-Harris, R. L., Roseman, L., Trautwein, F. M., & Berkovich-Ohana, A. (2018). Psychedelics, meditation, and self-consciousness. Frontiers in psychology, 9, 1475.
[8] Shear, J., & Jevning, R. (1999). Pure consciousness: Scientific exploration of meditation techniques. Journal of consciousness studies, 6(2-3), 189-210.
[9] Kant, I. (1908). Critique of pure reason. 1781. Modern Classical Philosophers, Cambridge, MA: Houghton Mifflin, 370-456.
[10] Friston, K., Kilner, J., & Harrison, L. (2006). A free energy principle for the brain. Journal of physiology-Paris, 100(1-3), 70-87.
[11] Skora, L. I., Seth, A. K., & Scott, R. B. (2021). Sensorimotor predictions shape reported conscious visual experience in a breaking continuous flash suppression task. Neuroscience of Consciousness, 2021(1), niab003.
[12] Friston, K., Mattout, J., & Kilner, J. (2011). Action understanding and active inference. Biological cybernetics, 104, 137-160.
[13] Seth, A. (2021). Being you: A new science of consciousness. Penguin.
[14] Friston, K. (2013). Life as we know it. Journal of the Royal Society Interface, 10(86), 20130475.
[15] Metzinger, T. (2020). Minimal phenomenal experience: Meditation, tonic alertness, and the phenomenology of “pure” consciousness. Philosophy and the Mind Sciences, 1(I), 1-44.
James Cooke is a neuroscientist, writer & speaker, focusing on consciousness, meditation, psychedelic states, science and spirituality.
Additional Reading：
Post-liberalism and its dangers
Misinformation is the symptom, not the disease
A New Model of Consciousness By Daniel Stoljar
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科學家研究如何測量意識的複雜度 -- Oshan Jarow
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A new approach to measuring what’s going on in our minds
Quantifying the “complexity” of consciousness can tell us how rich our experiences are.
Oshan Jarow@OshanJarow, 12/15/23
Sometimes when I’m looking out across the northern meadow of Brooklyn’s Prospect Park, or even the concrete parking lot outside my office window, I wonder if someone like Shakespeare or Emily Dickinson could have taken in the same view and seen more. I don’t mean making out blurry details or more objects in the scene. But through the lens of their minds, could they encounter the exact same world as me and yet have a richer experience?
One way to answer that question, at least as a thought experiment, could be to compare the electrical activity inside our brains while gazing out upon the same scene, and running some statistical analysis designed to actually tell us whose brain activity indicates more richness. But that’s just a loopy thought experiment, right?
Not exactly. One of the newest frontiers in the science of the mind is the attempt to measure consciousness’s “complexity,” or how diverse and integrated electrical activity is across the brain. Philosophers and neuroscientists alike hypothesize that more complex brain activity signifies “richer” experiences.
The idea of measuring complexity stems from information theory — a mathematical approach to understanding how information is stored, communicated, and processed —which doesn’t provide wonderfully intuitive examples of what more richness actually means. Unless you’re a computer person. “If you tried to upload the content onto a hard drive, it’s how much memory you’d need to be able to store the experience you’re having,” Adam Barrett, a professor of machine learning and data science at the University of Sussex, told me.
Another approach to understanding richness is to look at how it changes in different mental states. Recent studies have found that measures of complexity are lowest in patients under general anesthesia, higher in ordinary wakefulness, and higher still in psychedelic trips, which can notoriously turn even the most mundane experiences — say, my view of the parking lot outside my office window — into profound and meaningful encounters.
Increasing richness isn’t just like cranking up the color saturation of a picture or getting a bigger hard drive. It seems to imply an increase in the depth of how we experience the world. Complexity is what you see in the equations, richness is what that feels like in the mind.
Although measuring brain complexity is still in relative infancy, the nascent ability to gauge something like richness is a pretty incredible development — not only for neuroscience but for how we think about well-being more broadly. With innovations like these, we can go beyond the blurry question of happiness, which doesn’t have an accepted neurological measure that can translate across social and cultural differences, and ask more targeted questions, like whether our experiences are richer. As these approaches mature, scientists might develop a deeper understanding of all the different, tractable ways that consciousness can change for the better.
From staining neurons black to measuring the brain’s complexity
In the 1800s, scientists studying the mind didn’t yet know what a neuron looked like, let alone how they worked. That breakthrough came in 1873, when physician Camillo Golgi discovered that by immersing brain tissue in a potassium dichromate solution and then dunking it in a bath of silver nitrate, the neuron would turn black, making it visible under a microscope.
The Spanish neuroscientist Santiago Ramón y Cajal, when observing newly stained neural tissue in 1887, discovered that contrary to the reigning reticular theory (which held that the nervous system was a continuous network of cells smushed together with no gaps), neurons were indeed separated from each other. Sprouting from the neuron’s edges were spindly little axons and dendrites, but they didn’t seem to create permanent bridges between the neurons, leading him to conclude that communication between neurons likely wasn’t all that important in explaining their main functions. Instead, individual neurons were taken as the nervous system’s fundamental units, or building blocks, an idea that solidified into “the neuron doctrine.”
Through the 20th century, developments in electrophysiology led to a sharper understanding of the connections between neurons, and the importance of the little electrical impulses that travel across synapses. But the basic perspective of focusing on neurons themselves, rather than the holistic electrical processes that they’re conduits for, remained dominant. This approach has gotten quite good at breaking the brain into distinct parts and explaining how they contribute to specific functions, like vision or controlling your fingers. The downside is that many theories of consciousness struggle with what’s called the binding problem — the question of how all the separate parts fit back together to generate a unified conscious experience.
Recent improvements to electroencephalography (EEG, those skull caps with a bunch of electrodes that measure the brain’s electrical activity) made it possible to look deeper inside the workings of the brain, opening the way for neuroscientist Giulio Tononi and biologist Gerald Edelman’s 1998 paper: Consciousness and Complexity.
Their publication was the first to propose a direct measure of the complexity of brain activity, an idea that matured into Integrated Information Theory, or IIT. According to IIT, consciousness arises where the underlying neural activity is both “integrated” and “differentiated.” Integration refers, roughly, to how synchronized electrical activity is across the brain. Differentiation is the diversity of that activity. You can think of them in terms of weaving a tapestry. Integration is how many different threads are woven in, while differentiation is the variety of colors used. Together, these two determine the complexity of a given state of consciousness. That, in turn, approximates its richness.
In theory, anyway. At the time, the idea ran ahead of technology. “It became apparent over the years that it’s quite hard to measure those two things simultaneously,” Barrett told me, “and it turned out that the differentiation aspect alone, without thinking about integration, did quite well at being able to distinguish between different states of consciousness.”
That said, our measures are improving quickly. Barrett co-authored a study released as a pre-print last week that compared a new measure of complexity — what they call “statistical complexity” — to Lempel-Ziv complexity, which was first proposed in 1976 and is still the field’s leading measure. While Lempel-Ziv captures only the differentiation aspect, their findings suggest that the new measure successfully brings integration back into the mix, affording greater precision.
As progress continues, IIT may creep closer to its grand ambition: constructing an equation that can measure and describe the richness of conscious experience in any physical system, whether human, animal, or machine. “That fails at the moment,” said Barrett, “but I’m very interested in seeing if we could come up with a plausible equation. That’s sort of the holy grail for me.”
So what do we make of richness?
If a plausible equation isn’t the kind of thing that occupies your dreams, a concrete measure for something like richness could bring some sorely needed innovation to our ideas around mental health. The Diagnostic and Statistical Manual of Mental Disorders (the DSM-5) contains 298 diagnoses to help clinicians classify just about every shade of mental disorder they might encounter. When it comes to the positive dimensions of mental health, however, our language is comparatively sparse.
“Happiness” is a very nebulous idea, especially when you try to measure it. We in the West, unlike the Buddhists, have not developed rigorous taxonomies for all the rungs on the mental ladder — from our default modes to the ecstasies, grades of zest, or senses of “deep okayness” that lurk in the upper realms of well-being (reportedly, anyway). If we can quantify the richness of our minds, maybe it could jumpstart the process of finding other tractable dimensions we can add to our conceptions of well-being.
Of course, quantifying something important always carries risks (à la Goodhart’s law: when a measure becomes a target, it ceases to be a good measure), and being wise about how to make sense of these new ideas will be bumpy. It’s tempting, for example, to simply think that when it comes to richness, more is always better. But researchers, like Future Perfect 50 honoree Robin Carhart-Harris, believe that the brain evolved to hold levels of complexity below a threshold called “criticality,” rather than just maximize it.
In information theory, criticality marks the optimal balance of complexity for processing information, a perch between order and chaos. Or in terms of the mind, between the rigidity and flexibility of mental habits. Too much complex activity pushes the brain over the edge. That might offer a temporarily exciting state of mind (as psychedelic trips can), but in terms of efficiently processing information to be successful creatures in the world, a never-ending acid trip is probably not the ideal state. “A brain at criticality may be a ‘happier’ brain,” Carhart-Harris writes.
If criticality means greater well-being calls for a particular balance of complexity, not just as much as we can muster, that doesn’t mean that we’re all, by default, naturally tuned to that balance. As our measures and technologies improve, maybe we’ll get better at identifying when someone’s ordinary brain activity is below criticality, and a burst of complexity could serve as a boon to well-being. Maybe we’ll develop new ways of growing richer, not just in our bank accounts (though that may help), but in the ways that we experience the world.
Oshan Jarow is a Future Perfect fellow, where he focuses on economics, consciousness studies, and varieties of progress. Before joining Vox, he co-founded the Library of Economic Possibility, where he led policy research and digital media strategy.
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