Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts

I have long been fascinated by the mystery of consciousness, and Stanislas Dehaene’s Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts delivers one of the most satisfying and scientifically grounded explorations I’ve read. I was delighted to add this edition to my personal collection, and it has already become a book I return to and recommend often Dehaene, a leading cognitive neuroscientist, masterfully synthesizes years of rigorous experimental work from his lab and others around the world. Using clever paradigms such as visual masking, binocular rivalry, and attentional blink, combined with EEG, fMRI, and other imaging techniques, he shows how the brain distinguishes unconscious processing from conscious awareness. The central idea, the global neuronal workspace theory, is presented with clarity and precision: consciousness arises when information is amplified and broadcast across distributed cortical networks, enabling integration, reportability, and flexible use in thought and action. What makes the book exceptional is its balance. It is deeply rigorous yet remarkably accessible, full of vivid examples and “signatures of consciousness” (distinct late, global patterns of brain activity) that mark the moment a stimulus enters awareness. Dehaene also thoughtfully explores why so much of our mental life remains unconscious and what consciousness is actually for. The implications for understanding disorders of consciousness, anesthesia, and even future questions about artificial systems are profound and responsibly discussed. This is not armchair philosophy, it is neuroscience at its best: evidence-driven, elegantly written, and genuinely illuminating. Whether you work in the field or are simply curious about how the brain generates thought and subjective experience, this book is essential. I give it my highest recommendation.

As a physician and Stanford researcher (initially in artificial intelligence and currently in cognitive neuroscience), I have been interested in consciousness research for 50 years. How does the brain create consciousness? And, if this is "simply" a story of billions of spiking neurons talking to one another, can it be done in silicon? (If so, this may occasion a profound turning point in human history.) I have followed Professor Stan Dehaene's prestigious journal publications for a decade as he has amassed a wealth of evidence supporting the view that consciousness is 1) experimentally accessible, 2) has reliable neural correlates (signatures), and 3) is functionally important . Dehaene (a professor at the College de France in Paris and director of the INSERM Cognitive Neuroimaging Unit) is one of the world's leading scholars of consciousness. Fortunately for us, his literary agent, John Brockman (of "Edge" fame) persuaded him to write this popular work. That Dehaene writes this well in English makes me wonder how spectacularly he must write in his native French. We are not only transported to the cutting edge of research on consciousness, but the voyage is a thrill. As expected, Dehaene is thoroughly steeped in the history of consciousness from Plato, through Descartes, Hume, and the Continental philosophers. His writing is also filled with references to French art, literature, and humanism (like serotonin molecules, that culture seems to have diffused from the Louvre down the Boulevard Saint-Michel and become bound in this book.) Right from the start (see the beautiful, free Introduction on Amazon) he reminds us that it all began in the caves at Lascaux with the depiction of a dreamer's soul wafting about like a sparrow. Deftly weaving ancient Egyptian mythology with the Upanishads, he transitions to Descartes and his alleged "Error." Rightfully defending his countryman, Dehaene takes contemporary pop-neurosci to task. Descartes was no dualist (body + immaterial soul) blinded by religion. Rather, he was genuinely grappling with the central problem of this book and the field. How does conscious perception, reflection, and deliberation emanate from a machine? In seven chapters, Dehaene carefully steps us through all the evidence (from his large Paris group and the world's other top labs) of the brain's signatures of consciousness. How can one even study consciousness in the lab? (Chapter 1) The key innovation was the discovery and exploitation of "minimal contrast" phenomena. When presented just too faintly, too rapidly. or when masked they are completely invisible. But, increase the intensity, duration, or remove the mask and there they are, plain as day. I'll list these, but do yourself a favor and go to YouTube to see them for yourself: motion-induced blindness, change blindness, attentional blink, binocular rivalry, multistable perception. Now you see it; now you don't. (Also, go to Charlie Rose's website and look at the episode on consciousness in which Nobelist Eric Kandel interviews Dehaene and other stars of this field.) We are obviously conscious, but is there any neural processing of which we are NOT conscious? (Chapter 2) Yes, most of it! Non-conscious and pre-conscious processing is ubiquitous, functional, and essential. He reviews fascinating experiments that reveal the pervasive and essential role of non-conscious processing in language, vision, hearing, and action. Consciousness is the tip of the iceberg. Perhaps consciousness is epiphenomenal (a non-functional add-on, like the roar of a jet plane). In Chapter 3 he dismisses that old, profoundly counter-intuitive proposition. His argument here is reminiscent of Kahneman's Thinking Fast and Slow. Fast (nonconscious) thought is fine for practiced, routine, reflexive speech and action. But thinking and action marked by careful deliberation and planning requires consciousness: the ability to maintain a percept in working memory and mull it over. Chapter 4 displays the core findings of the experimental work: the neural signatures of consciousness. These are what Nobelist Francis Crick and collaborator Christof Koch called the neural correlates of consciousness. (See Koch's excellent work "The Quest for Consciousness") Even invisible, unseen (subliminal) stimuli excite chains of neural firing but only in primary sensory areas. However, when a stimulus crosses the threshold into consciousness, the neural firing is strongly amplified in intensity and distribution as many brain regions ignite and communicate especially prefrontal, parietal, and anterior temporal areas. In Chapter 5 he describes a tentative theory that accounts for the experimental findings: the global neuronal workspace theory. I'm old enough to recall the origin of this theory as the blackboard model from 1970s AI research sponsored by DARPA that led to the then famous Hearsay-II speech understanding system from CMU. In an interesting quirk of history, this excellent work was dragged into oblivion by the AI Winter of the 1980s. But, the theory itself became resurrected as a theory of consciousness by psychologist Bernard Baars. (See Baars' 1988 A Cognitive Theory of Consciousness). With the 1990 advent of fMRI, this theory became ripe for experimental verification. Entrez Professeur Dehaene. Not only can he explain the lab details from Chapter 4, he has also built a computer simulation of a spiking neural network that exhibits the same behavior. As you may know, Europe has just embarked on a ten year 1.5 billion dollar project to simulate the human brain. While this project may seem to be irrationally ambitious, I am comforted in knowing that Dehaene is one of the scientists at the helm. Chapter 6 deals with the crucial topic of coma and vegetative states. It opens poignantly with the case of Jean-Dominique Bauby, the Editor of Elle, who had a brain stem stroke, and though entirely paralyzed (save for one eye), wrote an entire book "The Diving Bell and The Butterfly" by blinking that eye. EEG, MEG, and fMRI signatures of consciousness may in the future help us to decide which coma patients are conscious and which are not. He closes in Chapter 7 with the future: tests for animal consciousness and machine consciousness. While machine consciousness may someday be possible, it will not happen soon. Nonetheless, this work paves the way to it by showing the functional properties of the only system that we know is conscious: ourselves. Although I've read widely on this topic (and cover AI and Stanford neuroscience on my website: bobblum) , there was much here that was new to me. This is an outstanding work on the basis of both scientific and literary merit.

This book is an impressive tour de force on the research on consciousness, particularly on the question of what makes the difference between a conscious and an unconscious perception. I flash the image of a coffee cup on a computer screen briefly, followed by a "masking" image (say, of random lines). If the mask follows the coffee cup too closely in time, the cup is never seen - make the gap in time between cup and masking image a little longer, the cup is seen. What is going on in the brain that makes the difference? What makes the cup "accessible" (gives it "access" in consciousness, or not? That is, how to explain "access consciousness." That the unseen/unregistered cup has been perceived unconsciously, that there are real effects of this hidden perception that can be shown, is one of the fascinating stories in Dehaene's book - by the way, eerily confirmative via now current, open science (though Dehaene doesn't go into the subject), of widely-read books circa 1970's (sorry, don't remember titles) arguing that industry psychologists had extensive, but non-public studies on this effect and were using this subliminal effect widely in marketing. Along the way, Dehaene develops his concept of "signatures" for consciousness - areas of the brain that must be involved in the brain's processing for the coffee cup to be perceived. This includes, for example, the P3 "wave" - a synchronous firing of a set of these areas. The book is very detailed, yet readable; the case for his conclusions thoroughly made. A read to be appreciated for the great deal of information it provides. On the downside, Dehaene's overarching sense that neural processes will ultimately explain consciousness - understandable given his complete and impressively energetic absorption for years in this framework - leads him to treat the question too cavalierly, giving the impression to the reader - as so many other books in the neuroscience realm - that this is virtually "settled science," that all experience - normal, mystical, spiritual - is simply "generated" by the material brain (as though we actually understand "matter"). Thus for him, Chalmers' hard problem - how physical processes in the brain actually give rise to subjective experience (or "phenomenal" consciousness as opposed to "access") - will simply evaporate "when educated by cognitive neuroscience and computer simulations." The difficulty is that Chalmers' formulation of the problem in terms of "qualia" - explaining how a neural (or computer) architecture generates, or accounts for, the "redness" of an apple, the "blue" of the sky - has been misleading, obscuring the fact that the problem is actually explaining the origin of our image of the external world - not only the whiteness of the coffee cup on the kitchen table, but the cup itself, the stirring spoon, the swirling coffee surface (form, particularly dynamic, changing form, is equally non-computable), the table's stretching oak surface, the tiled floor, the pots hanging from the ceiling, the pictures on the walls... There is nothing of course that remotely looks like the kitchen in the brain; there is no image in the brain, there are only neuro-chemical flows. Yet this is a problem - a problem that dwarfs teasing out the nature of "access" consciousness, a problem for which, after 20+ years of attempted solutions, it is safe to say a good proportion of theorists see a radical breakthrough as necessary - that Dehaene simply asserts, with only a short discussion, will be solved, and solved within the information processing framework to which he gives complete allegiance. An example of how vastly misplaced and therefore misleading this faith could be is helpful. Henri Bergson, for example, in "Matter and Memory" (1896), 50 years before Gabor's discovery of holography, presciently envisioned the universe - the vast material field in which the brain is embedded - as a holographic field (for this reason the theory was never understood by his contemporaries). Effectively he saw the brain as forming a modulated reconstructive wave passing through this holographic field and "specific to" a subset of the information in the field, by this process the subset now becoming an image - the coffee cup, kitchen table, the hanging pots. Such a view would treat all the "computations" envisioned in the information processing framework (to include the "P3") as being part of a very concrete dynamics - a very concrete wave passing through the holographic field - as concrete, say, simply an example, as an AC motor generating a field of electric force. This would mean that the problem of constructing the operations of the brain, rather than discovering the correct software and/or neural net connections, is in fact a massive physics/engineering problem. A "computer simulation" of an AC motor runs not one Christmas tree light. Since, in this model, the image of the external world (read, our experience) is not occurring within the brain, memory (our experience) cannot be solely stored in the brain, demanding then a completely different notion of memory retrieval and therefore, of cognition/thought. As Bergson's model requires that the flow of time be understood as indivisible or non-differentiable, and for him, the relation of (conscious) subject to (perceived) object is not in terms of space, but in terms of time, even more paradigm changing considerations must be introduced. Dehaene, however, focused and working so diligently as he is in a standard information processing/philosophical framework, has given little time to these considerations, at least in the book, whether of time and mind, of the deeper nature of the hard problem, of the many, many actual problems with current memory theory and its standard notion (read dogma) of the storage of experience in the brain. This is understandable, but nevertheless the book does a disservice here in allowing readers, with so little space given to a real analysis, to come away with the (rather ubiquitous) impression that, a) this information framework is all there is, and, b) more of the same will solve the problem. Nevertheless, as noted, an interesting, very informative read.

I loved this book because it is just in the border line that divides science from free and mere speculation. The author is clear to separate what he thinks from what he knows. In doing this, he gives us a lesson of how science advances by keeping under control its most cherished assumptions. Now the book is about the relationship between consciousness and the brain. To do this, professor Dehaene proposes a mechanism that explains with accuracy what conscience is, how it works and for what. His mechanism is far from being completed because there is an inherent complexity in the brain that cannot be solved with the tools we have today in terms of technology. To be precise, this is how he tells us about his findings: "My collaborators and I have elaborated a theory that we call the 'global neuronal workspace.' We propose that consciousness is global information broadcasting within the cortex: it arises from a neuronal network whose raison d’être is the massive sharing of pertinent information throughout the brain." Troughout the book, also, in very illustrative seven chapters, professor Dehaene unfolds his theory by explaining what we knew about consciousness before, say, 1980's and what we began to notice since then. The book has several graphs and illustrations that accompany the text in a very good manner. It has many examples about people who has suffered brain damage and how that unfortunate state has made possible for scientists to prove or understand part of the challenge of getting to know what consciousness is. But not only that: there is a lot of experiments that have tested some hypothesis and shedding new light on the subject. As long as you read, you discover that nothing about consciousness has been easy. Far from that. The subject is one of the most difficult task that humanity has undertaken. I guess it is rightly the most difficult of all. In his own words: "Today the problem of consciousness is at the forefront of neuroscience research. It is an exciting field with its own scientific societies and journals. And it is beginning to address Descartes’s major challenges, including how our brain generates a subjective perspective that we can flexibly use and report to others. This book tells the story of how the tables have turned." As I said: this book is about the state of the art about consciousness. It gives you a very informative and serious outlook about the subject, with a complete view on the importance and the consequences of knowing at last how conciousness works and what we should expect to know in the near future. There's a lot of people who suffers right now of painful and/or strange mental dissorders. If professor Dehaene is right, perhaps we see those patients, at least some of them, to live better lifes. In this book you see how close the science is of the problems and necessities of the people. Impressive. Share with me the pleasure of this reading.

Consciousness has proved extremely elusive for science and for philosophy. Even as we have come to understand more and more about the brain the mystery of consciousness has remained one of the most puzzling enigmas of the universe. We are still a long ways away from understanding consciousness but there have been some very interesting developments in the last decade or so and Stanislas Dehaene's book is a great introduction to those developments for the lay person. Dehaene begins by outlining some of the new experimental evidence relating to the study of consciousness. One of the major stumbling blocks for consciousness research has been its seemingly "subjective" character. How can a science that aims to study phenomena "objectively" deal with phenomena that are fundamentally "subjective"? Many scientists believed this stumbling block was insurmountable and that consciousness research would always remain within the province of philosophers and mystics. However, scientists have proven resourceful in designing creative experiments that have allowed them to bridge - to some degree at least - that objective-subjective divide and Dehaene introduces the reader to these new experiments and their exciting findings. After providing a great deal of experimental evidence, Dehaene attempts to develop a new theory of consciousness. I am sure Dehaene would be the first to admit that we are still a long ways away from being able to work out a full fledged theory of consciousness that is fully capable of accounting for the phenomenon as a whole. However, Dehaene's theory is a good start and it is a testable theory that can help guide further consciousness research. In brief, Dehaene theorizes that consciousness is a phenomenon that takes place when a phenomenon reaches a critical threshold of importance in the brain and the messages reporting the various aspects of that phenomenon become synchronized and broadcast throughout the brain as a whole. Whether this theory is able to resolve the hard problem, or the explanatory gap, I will leave up to the reader to decide but, whatever the case may be, anyone who is looking for a good, accessible introduction to the current state of consciousness research could not find a better book than Dehaene's.

This book is impressive : In case you’re interested in this great mystery we all (are supposed to) have up there between our ears, you’ll been given a priviledged access to the state of the art in neuroscience : Stanislas Dehaene style is so much concise, accurate and efficient than you’ll feel yourself intelligent when reading... His tentative theory of consciousness (GNW) is very convincing, as it emerges progressively after the introductory chapters relating up to date experimental paths, then leading conclusively to the most plausible theoretical standpoint. You’ll never be completely done with this little book, which by itself deserves being read a number of times to allow integration of the huge amount of personal conclusions you can draw from its content. My best advice is then : Buy this book ASAP. Find an accessible place for it in your library. Read it (at least) twice. And feel the enlightenment of being taught a (very) difficult but essential matter, by a Professeur at College de France. You’ll like that... 😉

Consciousness and the Brain by Stanislas Dehaene is a great introduction for anyone interested in learning about key ideas in neuroscience. Consciousness is a fascinating natural phenomenon, although it is not yet completely understood. Dehaene provides a solid overview of the many disparate fields that probe this concept. On a psychological level, Dehaene talks about specific phenomena, such as subliminal priming and the Wheatstone stereoscope related to binocular perception, and how they give clues into the conscious mind. He also underscores the importance of subliminal thinking for much of what we do. In terms of brain physiology, Dehaene describes the different areas of the brain and the importance of the prefrontal cortex and the large pyramidal neurons it has in maintaining conscious thought. On a more basic chemical and physical level, Dehaene describes many of the techniques that scientists use to learn about the brain, such as EEG and fMRI. He touches upon some of the key underlying phenomena such as the P300 wave, thought to be a signal of consciousness. Dehaene also describes a number of grand, but speculative, theories of consciousness. For example, he discusses the workspace theory of the mind, as well as an “applause” concept that posits that conscious ideas are amplified and step above all the other things on one's mind. Overall, I found this an excellent read for someone wanting to learn about the mind, and I would recommend it heartily.

A somewhat interesting book. I think most of these writers (the writers that write about consciousness) recycle about 50% of the same material; they all experimented on the same epilepsy patients. This book should have been about a 120 pages total. Too much material is repeated throughout the book; you'll get that deja vu feeling throughout. Also, I got to the point that whenever he said "we/they came up with an exciting experiment" or "we/they came up with a simple experiment" I instantly though, "please no, not another image or word injected at subconscious level." ...i'm just trying to finish the book at this point. Edit: Chapter 6 redeems itself and Chapter 7 is not too bad. After sitting down and thinking about it, I realized that most people will not read multiple books on consciousness and it is in fact necessary to regurgitate the same information as other authors have done in order to introduce the reader to the fundamentals.

I really enjoyed reading this book. Even though I was rather interested in self-consciousness, the main theme of conscious access was profoundly interesting.

This book isone of the most entertaining yet scientifically detailed that I have ever read on consciousness. It gives both a view of the latest progress we have made thanks to new brain imaging techniques as well as references to patient cases from the past that still shed light on current theories of consciousness.

The writer acknowledges that our understanding of consciousness is rudimentary, so his research is through the "conscious access" approach, which the writer argues is the only one that can be scientifically tested. He omits vigilance and attention consciousness. A very good read, albeit some parts are technical. I recommend this book to yogis who wish to learn about the approach that only the brain, through its complex processes, produces consciousness.

Fue un regalo, y el tema es interesante, bien desarrollado en este libro. Recomendable.

A great book and must read for all that want to understand more on how our brains operate.