The Quest for Consciousness: A Neurobiological Approach (Hardcover)

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Editorial Reviews

From Scientific American

When he was still a student, Richard Feynman hinted at a career to come as a scientific wonderer when he wrote: "I wonder why. I wonder why. / I wonder why I wonder / I wonder why I wonder why / I wonder why I wonder!" Such wondering, and meta-wondering, takes us to the heart of what geneticist-cum-neuroscientist Francis Crick (who would know) calls "the major unsolved problem in biology"--explaining how billions of neurons swapping chemicals give rise to such subjective experiences as consciousness, self-awareness, and awareness that others are conscious and self-aware. The body of literature attempting to solve this problem is extensive, and getting one's mind around the field is a herculean task successfully executed by psychologist Susan Blackmore in her delightful introduction, Consciousness. Presented as a textbook, it is so highly engaging that I recommend it for general readers, too. In many ways, the book is structured like a brain, with loads of independent modules (boxes and sidebars featuring profiles, concepts and activities) tied together by a flowing narrative and integrated into a conceptual whole. The easy problem, Blackmore says, is explaining each of the functional parts of the brain, such as "the discrimination of stimuli, focusing of attention, accessing and reporting mental states, deliberate control of behavior, or differences between waking and sleep." In contrast, the hard problem in consciousness studies "is experience: what it is like to be an organism, or to be in a given mental state." Adding up all of the solved easy problems does not equal a solution to the hard problem. Something else is going on in private subjective experiences--called qualia--and there is no consensus on what it is. Dualists hold that qualia are separate from physical objects in the world and that mind is more than brain. Materialists contend that qualia are ultimately explicable through the activities of neurons and that mind and brain are one. Blackmore, uniquely qualified to assess all comers (she sports multihued hair, is a devotee of meditation, and studies altered states of consciousness), allows the myriad theorists to make their case (including her own meme-centered theory) so that you can be the judge. Making a strong case for the materialist position is Gerald M. Edelman's latest contribution, Wider Than the Sky, offered as a "concise and understandable" explanation of consciousness "to the general reader." Concise it is, but as for understandable, Edelman understates: "It will certainly require a concentrated effort on the part of the reader." As director of the Neurosciences Institute in La Jolla, Calif., a Nobel laureate and author of several books on consciousness (Neural Darwinism, The Remembered Present and Bright Air, Brilliant Fire), Edelman has impeccable credentials. But science writing for a general audience involves more than expunging scholarly references and providing a glossary of technical terms as a substitute for clear exposition. To wit, on memory Edelman writes that "it is more fruitfully looked on as a property of degenerate nonlinear interactions in a multidimensional network of neuronal groups." Such prose is common throughout the book, which is a shame because Edelman is a luminously entertaining conversationalist, and his theory that the brain develops in a Darwinian fashion of neuronal variation and selection, and that consciousness is an emergent property of increasingly complex and integrated neuronal groups, has considerable support from neuroscience research. An ideal combination of exquisite prose and rigorous science can be found in California Institute of Technology neuroscientist Christof Koch's The Quest for Consciousness. A rock climber adorned with a tattoo of the Apple Computer logo on his arm, Koch takes an unabashed neurobiological approach, the natural extension of what his longtime collaborator Francis Crick started in 1994 when he wrote in The Astonishing Hypothesis "that 'you,' your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules." To me, the most astonishing aspect of this theory is that it is astonishing to anyone. Where else could the mind be but in the brain? Nevertheless, finding the neuronal correlates of consciousness (NCC) has proved elusive, so instead of concocting a grand unified theory, Koch and Crick undertook a very specific research program focusing on the visual system, to understand precisely how photons of light striking your retina become fully integrated visual experiences. Koch and his colleagues, for example, discovered a single neuron that fires only when the subject sees an image of President Bill Clinton. If this neuron died, would Clinton be impeached from the brain? No, because the visual representation of Clinton is distributed throughout several areas of the brain, in a hierarchical fashion, eventually branching down to this single neuron. The visual coding of any face involves several groups of neurons--one to identify the face, another to read its expression, a third to track its motion, and so on. This hierarchy of data processing allows the brain to economize neural activity through the use of combinatorics: "Assume that two face neurons responded either not at all or by firing vigorously. Between them, they could represent four faces (one face is encoded by both cells not firing, the second one by firing activity in one and silence in the other, and so on). Ten neurons could encode 210, or about a thousand faces.... It has been calculated that less than one hundred neurons are sufficient to distinguish one out of thousands of faces in a robust manner. Considering that there are around 100,000 cells below a square millimeter of cortex, the potential representational capacity of any one cortical region is enormous." Given that the brain has about 100 billion neurons, consciousness is most likely an emergent property of these hierarchical and combinatoric neuronal connections. How, precisely, the NCC produce qualia remains to be explained, but Koch's scientific approach, in my opinion, is the only one that will solve the hard problem.

Michael Shermer writes the Skeptic column for Scientific American and is publisher of Skeptic and author of The Science of Good and Evil (Henry Holt and Company, 2004).

Review

"An extraordinary book that outlines in clear terms the issues the biology of the mind will confront in upcoming decades." -- Eric Kandel, Author of Principles of Neural Science and winner of the 2000 Nobel Prize for Physiology or Medicine

"Once you start "The Quest for Consciousness" your mind makes you read through to the end as fast as possible." -- James Watson, Author of The Double Helix and winner of the 1962 Nobel Prize for Physiology or Medicine

"The Quest for Consciousness promises to be the most deeply informed and scientifically thoughtful book ever published on the subject." -- Joseph E. Bogen, Clinical Professor of Neurological Surgery, University of Southern California

"not only a mine of information, and full of provocative thoughts and insights, but a delight to read and ponder." -- Oliver Sacks, Author of Awakenings, The Man Who Mistook His Wife for a Hat, and Uncle Tungsten

See all Editorial Reviews

Product Details

• Hardcover: 429 pages
• Publisher: Roberts & Company Publishers; 1 edition (March 2004)
• Language: English
• ISBN-10: 0974707708
• ISBN-13: 978-0974707709
• Product Dimensions: 10.1 x 6.9 x 1.5 inches
• Shipping Weight: 2.4 pounds (View shipping rates and policies)
• Average Customer Review: 4.6 out of 5 stars  See all reviews (9 customer reviews)
• Amazon.com Sales Rank: #86,031 in Books (See Bestsellers in Books)

Customer Reviews

Most Helpful Customer Reviews

98 of 101 people found the following review helpful:

5.0 out of 5 stars Simply Outstanding, July 29, 2004

By	E. Roppo "science buff" (SF, CA, USA) - See all my reviews (REAL NAME)

This is the best popular neuroscience book that I have read, and I've read a couple dozen of them over the last 15 years. I can say without hesitation that it rasies the bar for popular neuroscience writing.

It's not so much that Koch is the best writer, although he's very good. The strength of Koch here is that he provides a great deal of detail about the processes he talks about, and he organizes the information in such a way that you don't get lost in anatomical terminology. A lot of neuroscience books may such things as 'lesions in the posterior parietal cortex are known to be related to a condition called 'hemi-neglect' where the patient is unaware of objects in the left hemisphere, despite the fact they can see them if asked' - while that's interesting, it's usually presented as a brute fact with no real grounding of what the posterior parietal cortex does or how it fits into the larger scheme of sensory processing. But Koch does a marvelous job of explaining how various regions function and interconnect with others, and how that results in what you experience, or even what you don't experience.

The word 'quest' in the title isn't just hyperbole, you really are on an adventure to find something very specific, which is laid out at the beginning of the book. What Koch is looking for is what is called the Neuronal Correlates of Consciousness (NCC), meaning specific neurons whose activity can be demonstrated to be causally linked to specific aspects of conscious awareness (i.e. subjective experience). In this case, because more is known about the visual system than almost anything else about the brain, and certainly any other sense, he narrows his search for the NCCs to those that underlie visual experience.

So, in effect, this book is about the visual system, specifically how and where it generates conscious awareness of visual stimuli.

His quest starts at the retina, where you get a wonderfully detailed and readable account of it's structure and activity, then you are whisked down the optic nerve to the Lateral Geniculate Nucleus (another structure I've read about many times before, but have never come away with a clear understanding of what it does until this book). After that you travel to the back of the brain to areas V1-V4 in the visual cortex which break down the signals from the retina into bits and pieces of contrast, lines, angles, shading, dark and light, color. Koch swiftly moves up the processing hierarchy, moving from basic perceptual bits and pieces to object recognition and attention.

There is a revealing discussion of non-conscious visual processing that is compelling, giving the reader a glimpse of the enormous behind-the-scenes power that the brain brings to bear on perception, which we are fortuitously, and by design, never aware of.

There's a good deal of detail throughout, but never does he get bogged down. It's written with clarity and always with a sense of how it all fits into the quest for the NCC. He makes some surprising judgments about what neuronal activities qualify, or don't qualify as NCCs. And he's very honest and humble about what is known, what is theory, and what is conjecture.

This book stands out on its own merit, but the more curious reader may want to visit Koch's website at Cal Tech (http://www.klab.caltech.edu/cns120/) where you can watch streaming video from his lectures that are organized along the same outline as the book, each chapter is presented in a lecture. I greatly enjoyed watching the lectures as I made my way through the book, although I will emphasize again that the book is superb without the lectures (you won't get as much information from the lectures as the book), but having both was great fun.

I can't say enough good things about this book, it was captivating from the opening page to the last. Everyone who wants to know more about the brain and consciousness would do themselves a great service by reading it.

36 of 46 people found the following review helpful:

4.0 out of 5 stars Good, September 20, 2004

By	Carlos Camara "marrorris2" (Monterrey, Mexico) - See all my reviews (REAL NAME)

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For the last couple of years, few sicentific progress seems to have been made in the study of consicousness. Philosophical books do not claim to make much progress. I mean, philosophers have been debating over things like representationalism for over 20 years now. But science is supposed to be different. But as hard as I look, most recent books are nothing but reviews of the literature of the last decade and popular sicence, simplified for the lay reader, that seems to make no progress.

This book is not that different. Koch is one of the pioneers in the field, along with the late Francis Crick. It seems the quarrell between the nobelists Crick and Edelman is over, as can be seen in chapter 19 of this book, since mostly their theories agree on the important points. THAT is progress enough.

The bulk of the book is not about the neural correlates of consicousness at all, but about visual neuroscience, and the relationship between cosnciousness and memory and attention. All these chapters offer few truly novel insights, but are not to be skipped by the begginer. The ideas of neural assemblies and competition of neuronal coalitions have been around a while (Susan Greenfields work, and Taylor's Race for Consicousness), but it certainly is exiting to see the breaktrhoughs made with studies on binocular rivalry. Now it is hard to see how useful the unconscious homunculus can be as a theorethical tool. I read it on a joint paper Koch wrote with Crick in a collection edited by Metzinger, I did not get it then and I do not get it now. As I understand it, Koch just talks about a central executive in the frontal cortex, an idea not new nor very groundbreaking. Koch's idea on the necessity for involvent of frontal cortex (through intersignaling with posterior areas) in the NCC is confusing. Maybe differetn types of consciousness could clarify the concept. Sensory consciousness seems to only depend on posterior regions, while working-memory-type consicousness seems to need the frontal areas. It seems clear, considering Koch's ideas on qualia, that he means something like this.

There are some very important contributions, however. Chapter 6 almost resolves the debate on wether V1 is consicous (it is not), and as Koch points out, this is a positive thing, sicne it shows that cortical areas can be analyzed separatedly, and explaining their contribution to consicousness is possible. It would be magnificent if we could further reduce the candidate cortical areas further, if only slowly. I am skeptic of Koch's ideas that maybe different types of neurons can be so characterized. What if we found allegedly "conscious" neurons in V1? It seems to me more plausible that the role a neuron plays in context to the region it is in is far more important than ther cell type instead. Of course, Im speculating here.

But speculation is something Koch does quite well. However, as it is custom, scientists speculate on philosophical issues in their science books, and I like to wonder what philosophers would have to say about that. Lets see. Koch mantains that the function of consciousness is to summarize the present state of the world to the organism, so that it can plan accordingly. This is a very good function, but by no means a novel hypothesis. Cambell, i his book reference and consicousness, mantains that consicousness determines the reference of a demonstrative and therefore justifies the cognitive processing (planning) of the object refered too. Cambell is a philospher and argues for this point forcibly. So here Koch could be on the right track. What about qualia?

Qualia, Koch argues, are symbols, mental shorthand, for the vast content of those mental states. Qualia, then, are the way it feels to represent the content (Koch talks of meaning, which by his use is familiar to intentionality) of those states. In essence, Koch is saying (Im interpreting here, i COULD be doing itt wrong) that qualia are representational, and that it is vy virtue of that fact that they have a function. Now this is a thesis with a lot of philosophical baggage, but that I think is highly plausible. Koch mantains that the content of a quale is determined by the context (penumbra) in where the quale lies, This certainly seems right. The neural correlates of a quale would appear in the context of surrounding neural activity, and the interconnection between these systems would link qualia to its content (meaning). All of this, however, sidesteps the issue of in virtue of what properies does the penumbra, or the quale for that matter, represent anything at all. This is not the same as asking why qualia feel like anything at all, question that neither I nor Koch can answer. So although Koch's speculations are interesting, they fail to really explain anything at all, unless he gives us bridging principles. He tries, when he writes about how meaning arose out of sensimotor interactions, intermodality connections, or genetical predispositions. However, the details have to be inferred by the reader.

Koch is also highly simplistic in his dealing of split-brain studies. It is by no means obvious that splitting the brain means splitting conscousness. There is a whole book dealing with this issue (Alexanders tHE Unity of consicousness), and there are some good arguments that Koch ignores. (not to be blamed for he is a scientist.....he did start the speculation game, though)

So this book is a good review of the field, presents some novel ideas and interesting speculations. It is recomendable for novel readers, and a must have for cosnciousness fans. But I still wait for a landmark book, the Astonishing Hypothesis of the new decade. Koch is a wonderful writer and a brilliant scientist, and I do not doubt he will someday deliver.

21 of 27 people found the following review helpful:

5.0 out of 5 stars What causes consciousness?, November 6, 2004

By	Jill Malter ([e-mail]) - See all my reviews (TOP 500 REVIEWER)

This is a great book that describes where we stand in the search for neuronal correlates of consciousness (NCC). The problem has been attacked by people from various different fields. Still, it has to be a biology problem. Consciousness clearly resides in the brain. If only we had plenty of examples of brain-damaged people ... some of whom clearly lacked consciousness, some who were almost conscious, some who were certainly conscious, some who were uncertainly conscious .... then maybe we'd work out what the key was. Luckily, we don't have all that many brain-damaged subjects.

Koch takes this sort of approach to the problem of discovering the NCC: he tries "to quantitatively correlate the receptive field properties of individual neurons to conscious perception." If there's no map between certain cells and the structure of a conscious perception, then it's unlikely that these cells are sufficient for that conscious percept. That means looking at what we'd normally think of as vision problems, optical illusions, attention loss, long and short term memory, and various automatic and semi-automatic responses to stimuli. What amazed me most was that the work on this subject is still easily readable by the layman.

One of the more interesting questions Koch raises is this: since consciousness resides in the brain, do we get two consciousnesses when we split the brain in two? Actually, (as Koch explains) this was studied by Roger Sperry, whose split-brain experiments on monkeys and other animals in the 1950s and 1960s showed that the two sides of the brain easily learn different responses to stimuli, indicating that these animals effectively possess two separate minds. There are, of course, as Koch describes, some human split-brain patients who also demonstrate this.

It's an interesting book that is easy to read. It's sobering to realize how little progress we've made on such a fundamental question.