The Quest for Consciousness: A Neurobiological Approach

by Christof Koch

About the Author

Born in 1956 in the American Midwest, Christof Koch grew up in Holland, Germany, Canada, and Morocco, where he graduated from the Lycée Descartes in 1974. He studied physics and philosophy at the University of Tübingen in Germany and was awarded his Ph.D. in biophysics in 1982. He is now the Lois and Victor Troendle Professor of Cognitive and Behavioral Biology at the California Institute of Technology. The author of several books, Dr. Koch studies the biophysics of computation, and the neuronal basis of visual perception, attention, and consciousness. Together with Francis Crick, his long-time collaborator, he has pioneered the scientific study of consciousness.

Genres: Science, Neuroscience, Psychology, Philosophy, Nonfiction, Biology, Brain

429 pages, Hardcover

First published January 1, 2004

About the author

is an American neuroscientist best known for his work on the neural bases of consciousness. He is the President and Chief Scientific Officer of the Allen Institute for Brain Science in Seattle. From 1986 until 2013, he was a professor at the California Institute of Technology.

Reviews

[Melee Farr · Rating 3 out of 5]

This was the longest 3-month read of my life. I did finish the bastard, though. If you want to enjoy it, read chapter 1, then skip to 9. The concept is fascinating: where is the seat of consciousness in the brain, and what, exactly, is consciousness - along with a little exploration in what consciousness is for. The execution was beastly. Even with a background in anatomy, I had no idea where the author was going with about half of the book, and was pretty pissed at him when I figured it out "You made me read 60 pages and study 5 diagrams just to tell me that that little place is NOT the seat of consciousness. Bastard." Still, the questions he posed held my interest enough to finish the book. Unfortunately, I still don't know the answers to them. Heh.

[DJ · Rating 4 out of 5]

Until recently, those interested in learning about consciousness have had just three options: (1) introspection (informative but deceiving), (2) books by philosophers (interesting but completely speculative), and (3) books by crazies (the majority of the literature on consciousness). Consciousness has long been a naughty word in science, but ho! No longer! While the "hard problem" of exactly why phenomenological states arise from the collective squirts of neurotransmitters washing across your brain at all is still a crapshoot, the relatively "easy problem" of correlating certain neural activity with certain phenomenological experiences is well underway.

Christof Koch of Caltech is one of the leaders in probing visual consciousness (or "awareness" if we are speaking to grant committees - shh!) - a particularly "easy" form of consciousness that is amenable to experiment both in humans. Dr. Koch's "quest" is to identify the minimal set of neurons whose activation leads to consciousness. The book provides a grand tour of all the interesting quirks and subtleties of visual consciousness discovered in the last few decades, painting a picture that is far more fractured and fragile than our daily experience might suggest. If you still cling to the picture of the homunculus dictator riding a meatbag mech warrior around the world, this book will, at the very least, convince you that biological dictators can't do their jobs without an army of unconscious robot agents. The book also includes some more speculative thoughts on the purposes and general nature of consciousness but, perhaps surprisingly for a book with such a lofty title, consists almost entirely of good old-fashioned science.

What Brian Greene's The Fabric of the Cosmos is to modern physics, Quest for Consciousness is to modern neuroscience - the finest popular account available for lawyers, stock brokers, and mailmen with a bad science habit. Koch's book might focus on visual consciousness, but he touches on learning and memory, motor control, and lots more on this quest and does so in his highly readable and concise style. While mucking around in neurobiology can make for dangerous trekking, Koch organized the book very well with small, informatively titled sections, making it easy to remember the salient point of a particular passage if you're a neuro-rookie and easy to skim a particular passage if you're a neuro-master.

For a more philosophical approach, I'd also recommend Daniel Dennett's Consciousness Explained.


WARNING: The rest of this review is a collection of my reading notes. Readability not guaranteed.


The evolutionary development of the brain makes it the ultimate kluge. New functions are continuous adaptations of old ones, making for some pretty wonky and unintuitive design principles. Speculative example: humans evolve disgust to avoid bad food. As humans form larger societies and viral epidemics become a problem, it becomes evolutionarily advantageous to avoid certain people. Rather than reinventing an avoidance mechanism, evolution simply co-opts the old disgust system (for dealing with bad food) to deal with potentially infected fellow humans.
Is the function of emotions to allow detected correlations without known functional relationships to influence decision making? (In other words, I might not know by what mechanism two things are related but have unconsciously noticed a pattern in their coincidence.)
Approach to decoding neural computation: consider that the typical sensory stimuli or brain info that feeds into a circuit will be highly tuned to the absolute scale, relative scales, and symmetries of that which it represents. Considering the nature of the input may constrain neural computation and suggest approaches to understanding it in a particular circuit.
Does our consciousness integration window increase in unfamiliar environments and/or decrease in familiar ones? Does it increase or decrease in rapidly changing environments? How does one test the integration window in a dynamic setting? Traditional artificial masking protocols used in highly controlled environments don't seem appropriate.
As consciousness seems to change continuously, does this mean that the NCCs (neural correlates of consciousness) must be constrained in their activation patterns? How does the continuity of conscious experience arise from the somewhat digital spiking of neurons? Is there perhaps a continuous "read-out" process wedged between NCCs and qualia? Does the distinction between discontinuous and continuous dynamics suggest a useful approach to decoding neural computation?
How does the brain optimize the balance between zombie agents and conscious processing? The zombie system offers speed at the cost of flexibility, operating through previously detected correlations and heuristics. Conscious processing offers flexibility at the cost of speed, offering a rich simulation of a series of events in order to consider and weigh consequences. (Simulation is the best word for this - you don't know where your thoughts will end until you "run the program.")
How might one quantify consciousness? Do more explicit representations lead to more meaning and hence more consciousness? Would this justify deeming babies "less conscious", since they have not yet developed the repertoire of explicit representations available to an adult?

[Brian · Rating 3 out of 5]

(3.0) Worthy goal, not sure I got much out of the book though

A noble goal: to find the neural correlate of consciousness (NCC), the network of neurons to point to as where perception 'happens'. To a neuroscientist, this is probably a tremendous amount of review. To a non-neuroscientist, probably way more neurobio than can be absorbed. But he does well to try to rule out places where consciousness cannot be (in vision, retina, V1, for example), and hints at where it might be (in vision, inferotemporal cortex?).

One criticism that others may disagree with is that he narrows the definition of consciousness quite a bit so that a layperson may be disappointed. He boils it down to the experience of perceiving (not of thinking, free will, emotion, introspection...but simply of the awareness of 'red' when looking at a red ball, for example). I agree with this decision, but he may want to choose another word besides consciousness?

I didn't quite follow (was I too sleepy?) the grand program of research he'd like to see that would uncover the NCC. It felt learned, though I don't think I'm taking a lot with me after having read it. I still think the CNS program (that Koch is heavily involved in) at Caltech is pretty awesome; I came pretty close to enrolling myself back in the day. ;)

[PouDa Sabry · Rating 4 out of 5]

أكثر من ستة أشهر قراءة بكتاب كريستوف كوتش وأفكار فرنسيس كريك مكتشف الدنا و مازال التساؤل قائم هل العالم الداخلي للأفكار والمفاهيم مخبأ دائما عن الوعي كما في العالم الفيزيائي؟!
يركز الكتاب علي الأشكال الحسية للوعي وعلي البصر خاصة أكثر من الوجوه الأخري للأحساس. يفترض كوتش وفرنسيس بأن الارتباطات العصبية للوعي تشيد علي أساس تمثيل عصبي صريح مثال صريح علي ذلك توجه اللحاء البصري الأولي أو تشفير الوجه أسفل الفص الصدغي وذلك شرط ضروري، لكنه غير كاف للارتباطات العصبية للوعي. بمعني أن الأنشطة في هذا اللحاء، كما هو الحال في الشبكية ضروي للرؤية العادية الواعية لكنها غير كافية ويحتمل أن الأحلام والتخيل لا تعتمد علي اللحاء البصري الأولي. نستنتج أن اللحاء البصري الأولي ليست جزءا من الارتباطات العصبية للوعي بالنسبة للرؤية.
الانتباه والوعي عمليتان متميزتان. ربما يكون نوع ما من انتقاء الانتباه ضروريا، لكنه ليس كافيا للإدراك الواعي.عند الانتباه لشئ لا يختفي باقي العالم لكن يوجه الانتباه التشفير المجمع لشئ واحد ويكبح الآخر ويسمي انتقاء الانتباه.
بالنسبة للحلات المزاجية والانفعلات أمثلة بارزة للعوامل التي يمكن أن تعدل الإدراك وتوجهه ولفهم ذلك أكثر يتم البحث عن الجذور الخلوية للإدراك الشعوري.
هناك علاقة بين الاستجابات العصبية والإدراك. لنتحدث عن الذاكرة التي تبدو متجانسة من عدة عمليات. في الارتباط الشرطي يربط الكائن حدثين متزامنين أو متزامنين تقريبا ببعضهما، بحيث يتنبأ أحدهما بالآخر.أما بالنسبة للذاكرة الإجرائة تحتوي علي تعليمات مثل قيادة الدراجة أو ربط حذاء أو تسلق جبل.
كما ذكرنا أن اللحاء ضروري لكنه غير كاف للإدراك بمعني أنه يوجد عوامل حركية حسية شديدة التخصص تعمل بشكل جيد دون أن تؤدي إلي أحاسيس ظاهرية. لنقل أن هناك رؤية للفعل ورؤية للإدراك. تشمل الأمثلة تعديل وضع جسمك، تقدير انحدار التلال والسير ليلا.
ربما نذهب في هذه النقطة إلي اسلوب فلسفي قديم بأن العوامل الزومبية تضبط عينيك ويديك وقدميك وتحول بسرعة معلومات حسية إلي نتاج حركي نمطي.
العمي البصري يفقد المرضي وجهها خاصا أو أكثر من الإدراك البصري، لكن يحتفظ بتفاعل بصري لافت بوضع اليد في شق باتجاهات مختلفة، مسك الأشياء بشكل صحيح. وهنا يجب الإشارة علي الذين يسيرون ليلا أثناء النوم ويحركون الأثاث، يفتجون باب الثلاجة او يقدودون سيارة. ولا يستجبون عادة لأوامر لفظية ولا يتذكرون ما حدث أثناء تلك النوبات، تتبع هذه الأفعال الآليه برنامجا داخليا.
الإدراك والارتباطات العصبية للوعي لا تنشأ متصلة كما يبدو في الواقع بل متقطعة. وخاصية الإدراك ثابتة في فترة معالجة واحدة، لقطة واحدة.
مشكلة العقل والجسد:
-لا يمكن الوصل إلي الأفكار بوعي. لا تعرف إلا انعكاساتها الحسية.
-الكثير من الأفعال الحركية، إن لم يكن معظمها استجابة للأحداث الخارجية سواء مؤقتة، سريعة، نمطية أو غير شعورية. تتوسطها عوامل زومبية مدربة ومتخصصة جدا لا ترتبط في ذاتها بالشعور الواعي يمكن اعتبارها انعكاسات لحائية عامة.
-مقدم الدماغ نسيج من الشبكات العصبية مترابط جدا. يناظر أي مدرك سواء واقعي أو متخيل ائتلافا من الخلايا العصبية.
- يمكن التفكير في لحاء المخ بأنه يتمتع بعقد وتعبر كل عقدة عن وجه لمدرك وعندما يفقد عقدة يفقد الكائن ذلك الوجه من أوجه الإدراك ولا بفقد الأوجه الأخري.

[Mohamedridha Alaskari محمد رضا العسكري · Rating 4 out of 5]

المؤلف باذل مجهود كبير في هذا الكتاب الذي يتضمن دراسات و تحليلات واوراق علمية كثيرة.. الا انني لم اكمل هذا الكتاب لأن الترجمة ركيكة وغير مترابطة في كثير من الاحيان, وقد يكون مضمون الكتاب عصي الى حد ما لترجمته الى العربية وهذا الامر يذكرني بلغة مارتن هايدكر الصعبة, وعليه سأقرا الكتاب باللغة الانكليزية لعلي اجده افضل من الان.

مشكلة الوعي لم تحل لحد الان وكل ما موجود من نتاج فكري هو عبارة عن محاولات جادة لحل هذا اللغز والمسمى بالوعي.

ويمكن ايجاز وتبسيط معنى الوعي من وجهة نظري بأنه تلك الادراكات التي يجعلها الدماغ تبدو منطقية من خلال مرورها خلال اجهزتنا الاستشعارية كالسمع والشم واللمس والتذوق والابصار الذي يعد له الدور الكبير في الوعي كون العينين م�� اعثد الاجهزة الحسية التي لها اتصال وثسق بالوعي.

الكتاب محاولة علمية جيدة لفهم الوعي ويفتح للقارئ افاق عديدة تسهل له عملية البحث عن الوعي.

[Erin · Rating 4 out of 5]

If I could recommend just one book on a neuroscientific approach to consciousness, this would be it. But don't expect any clear answers to be spelled out for you – we’re not there yet. In particular, Koch does not provide the reader with anything approaching a satisfying explanation of how subjectivity can arise from a physical system.

[Ram · Rating 5 out of 5]

This is THE book on consciousness if you're looking for a purely neurobiological approach. The picture is still very incomplete: Koch sticks to making claims based on hard scientific evidence, and makes no assumptions. If you don't mind using a bit of analytical philosophy to make the jump and build the entire picture, I'd recommend Metzinger's "Being No One".

Light entertaining read.

[Moneim · Rating 3 out of 5]

النسخة العربية رغم الترجمة الممتازة والجهد الجبار المبذول فيها الا انها سيئة ! يبدو ان المشكلة في اللغة العربية ذاتها وهيمنة الانجليزية كلسان للعلوم ... ربما المشكلة في طريقة العرض خاصة في ظل وجود تجارب معقدة نسبيا كان من الممكن يتحول الكتاب لفيلم وثائقي شيق .. او يمكن المشكلة في توقعاتي وفي الوعي في حد ذاته :D

[Steven H · Rating 5 out of 5]

A NEUROSCIENTIST SEEKS TO EXPLAIN CONSCIOUSNESS

Christof Koch is a German-American neuroscientist who is president and chief scientist of the Allen Institute for Brain Science, and was formerly a professor at the California Institute of Technology.

He wrote in the Preface of this 2004 book, “The mind-body dilemma can be expressed succinctly by the question, ‘How can a physical system, such as the brain, experience anything?’ … How is it… that neural activity can give rise to the sensation of a burning pain?… The matter becomes even more mysterious with the realization that much, if not most, of what happens inside my skull isn’t accessible to introspection. Indeed, most of my daily actions… work on autopilot, while my mind is busy dealing with more important things. How do these behaviors differ neurologically from those that give rise to conscious sensations? In this book, I seek answers to these questions within a neuroscientific framework. I argue for a research program whose supreme aim is to discover the neuronal correlates of consciousness… I survey the relevant anatomical, neurophysiological, psychological, and clinical data and weave these into a larger tapestry that constitutes a novel framework for thinking about the neuronal basis of consciousness.” (Pg. xv-xvi)

In the first chapter, he adds, “Here, then, is the charter for our quest: To understand how and why the neural basis of a specific conscious sensation is associated with that sensation rather than with another, or with a completely nonconscious state; why sensations are structured the way they are, how they acquire meaning, and why they are private; and, finally, how and why so many behaviors occur without consciousness.” (Pg. 4)

He outlines, “The working hypothesis of this book is that consciousness emerges from neuronal features of the brain. Understanding the material basis of consciousness is unlikely to require any exotic new physics, but rather a much deeper appreciation of how highly interconnected networks of a large number of heterogeneous neurons work. The abilities of coalitions of neurons to learn from interactions with the environment and from their own internal activities are routinely underestimated. Individual neurons themselves are complex entities with unique morphologies and thousands of inputs and outputs. Their interconnections, the synapses, are molecular machines that come equipped with learning algorithms that modify their strength and dynamics across many timescales.” (Pg. 10)

He continues, “My approach is… I take subjective experience as given and assume that brain activity is both necessary and sufficient for biological creatures to experience something. Nothing else is needed. I seek the physical basis of phenomenal states within brain cells, their arrangements and activities. My goal is to identify the specific nature of this activity, the neuronal correlates of consciousness, and to determine to what extent the NCC [neuronal correlates of consciousness] differ from activity that influences behavior without engaging consciousness. The focus of this book is on sensory forms of consciousness---and on vision in particular… discovering and characterizing the molecular, biophysical, and neurophysiological operations that constitute the NCC will likely help solve the central enigma, how events in certain privileges systems can be the physical basis of, or even be, feelings.” (Pg. 19)

He observes, “humans do differ fundamentally from all other organisms in their ability to talk. True language enables homo sapiens to represent and disseminate arbitrarily complex concepts… The primacy of language … has given rise to a belief among philosophers, linguists, and others that consciousness is impossible without language and that, therefore, only humans can feel and introspect. While this might be true, to a limited extent, about self-consciousness… all of the evidence … is fully compatible with the position that at least mammals experience the sights and sounds of life. At present, it is unknown to what extent conscious perception is common to ALL animals. It is probable that consciousness correlates to some extent with the complexity of the organism’s nervous system. Squids, bees, fruit flies… are all capable of fairly sophisticate behaviors. Perhaps they too possess some level of awareness; perhaps they too can feel pain, experience pleasure, and see.” (Pg. 13)

He notes, “Seeing seems simple… A few minutes of self-observation reveal, however, that the relationship … is far more complex. Experiences are not simply given… Rather, your mind… selects the few nuggets of information that are of current relevance from the vast flood of data streaming in from the sensory periphery… The brain… deals with this informational overload by selectively attending to a miniscule portion of it, neglecting most of the rest. By selectively ATTENDING to particular events of things out there, you choose one world to experience out of an uncountable number of universes.” (Pg. 153-154)

He points out, “Attention and consciousness are distinct processes. Some type of attentional selection if probably necessary… for conscious perception. When attending to something, the rest of the world doesn’t disappear. Even when lost in thought, you remain conscious of the gist of the scene in front of you… One role of focal attention is to resolve competition when two or more objects are represented within the same neural network. In that case, attention biases the assembly coding for one object, thereby suppressing the other.” (Pg. 171)

He states, “Try to introspect the next time you talk. You will hear well-formed sentences come tumbling out of your mouth, but without any knowledge of what entity formed them with the appropriate syntax. Your brain takes care of that quite well without any conscious effort on your part… Science has provided credible evidence for … what I call ‘zombie agents,’ that carry out routine missions in the absence of any direct conscious sensation or control. You can become conscious of the action of a zombie agent, but usually only after the fact, through internal or external feedback… zombie agents operate continuously in all of us. These agents have on unfortunate practical consequence. The mere existence of some seemingly complex behavior does not necessarily imply that the subject is conscious… Additional criteria must be devised to detect consciousness.” (Pg. 206)

He suggests, “If these sensory-motor… agents are so fast and efficient, why not dispense with consciousness altogether? Perhaps the organism would come out ahead in the long run if the slower, conscious planning stage were replaced by a bundle of nonconscious agents. The disadvantage would be the lack of any subjective, mental life. No feelings whatsoever! Given the many senses…breeding zombie agents for all possible input-output combinations is probably inefficient… Such a nervous system would, in all likelihood, be bigger and more flexible than a brain that follows a hybrid strategy of combining zombie agents with a more flexible, conscious module… natural selection favored brains that make use of a dual strategy.” (Pg. 237)

He says in a footnote, “I don’t distinguish between access and phenomenal consciousness. See [David] Chalmers for the sophisticated, eristic arguments concerning the ‘Easy Problem’ and the ‘Hard Problem.’ This dichotomy has generated a large secondary literature … There is no doubt that today… the phenomenal aspects of consciousness are very, very puzzling: a truly HARD problem. Whether it will remain a hard one with a capital H remains to be seen. Other philosophers recoil from the very idea of qualia having any sort of real existence… To them, the mind-body conundrum would disappear once we understood access consciousness and its material manifestations in the brain.” (Pg. 239)

He asks, “Could there be organisms like us but devoid of any conscious mental life? Possibly. But … [t]his account… is insufficient to explain why it should feel like anything to be conscious. One popular explanation is that these feelings, qualia, serve no useful purpose… This appears questionable. Qualia are too structured to be an irrelevant byproduct of the brain. I favor the idea that qualia are closely tied up with meaning.” (Pg. 247)

He argues, “there is no credible alternative to understanding consciousness by searching for the NCC… logical argumentation and introspection… are simply not powerful enough to crack this problem. You can’t reason your way to an explanation of consciousness. Brains are too complicated…” (Pg. 316) He admits, however, that “I know of no logical reason why you couldn’t [be a zombie], although life would be pretty boring without any sensations… However, evolution took a different turn on this planet.” (Pg. 318)

Of free will, he comments, “do the laws of physics leave room for a will that is free in the metaphysical sense?... there are no generally accepted answers. I do know of many instances of a dissociation between an individual’s action and her intentions… There are many extreme forms of dissociations between action and the experience of willing an action… But whether raising my hand was truly free…I doubt it.” (Pg. 325)

This book will be of keen interest to those studying neuroscience, and consciousness.

[David Olmsted · Rating 4 out of 5]

Because this book brings in real neuroscience data it is the best book on consciousness yet published. Consciousness is a combination of perception and conscious sensations called qualia, two different phenomena. Qualia is why we see the color blue instead of just blindly react to some neural signals as would zombies (we can do this up to a point in a phenomena called blind-sight which involves a primitive non-cortical neural pathway). One can have qualia without perception but not vice-versa as exemplified when some object pattern suddenly jumps out at you from a picture you have been viewing.

The foundational Qualia (feelings and primary sensations) are not generated in the brain regions that make us intelligent (although our pre-frontal "planning" cortex seems to add a valuation component). Because this book deals with consciousness it mainly deals with the qualia from the primary sensory cortical centers and not the deeper non-cortical feeling centers. "Split brain" patients have separated cortices but unified feeling centers. In a rare case in which both left and right cortices can talk the book reports this:

"this led to frequent back-and-forth between them, as when Mark (the researcher) echoed one of her statements that she did not have feelings in her left hand. She then insisted that her hand was not numb, followed by a torrent of alternating Yes's and No's, ending with a despairing "I don't know". (page 291)

So what is the evolutionary purpose of qualia? Does it use energy even though it is not affected directly by any known energy source (the frontiers of physics are at high energies, not the low energies of the brain)? While this book cannot provide definite answers it does make suggestions.

[aqeel · Rating 5 out of 5]

كتاب رائع يتحدث عن رحلة كريستوف كوخ لمعرفة المناطق العصبية المرتبطة بالوعي. يوجد بالكتاب الكثير الكثير من التجارب العلمية بنتائج رائعة.
دماغ الإنسان يعلم أشياءً انت بوعيك لا تعلمها. ويقوم بأمور أفضل واسرع مما تقوم بها وانت بوعيك.
Amazing book. speak about Christof Koch journey to discover Neuron correlated to consciousness. You'll find a lot of experiments with surprising results (at least for me :) ).
Human brain know things you consciously don't. And do some things better and faster than you do consciously.

[Nick Black]

looks like a good place to start!

[Vibhu AV · Rating 5 out of 5]

Although this book is primarily written by Christof Koch, the contents are fruits of his intense discussions with Francis Crick (co-discoverer of the DNA structure) and Koch’s own research into the field. “For reasons of his own, Francis chose not to be a co-author of this book,” he writes, alongside a strong foreword from Francis Crick.

The book starts with what needs to be explained. What is the relation between the conscious mind and the electro-chemical interactions in the body that gives rise to it? How do taste and crunchy texture of potato chips, the unmistakable smell of dogs, or the feeling of pleasure on seeing a loved one or a beautiful scenery, emerge from the network of neurons? The puzzle is, how can a physical system have qualia? However, rather than a top-down approach which makes the problem intractable, Koch tries a bottom-up method. For this purpose, Koch defines the Neuronal Correlates of Consciousness (NCC, but it is unclear who introduced the terminology) and his quest focusses on finding them. As of now, the question of consciousness—how it happens, how it gives rise to qualia, etc.—are still unknown and therefore the quest is still a quest—incomplete and unanswered, but probably in the right direction. Also, since the quest is from a neurobiological viewpoint, the physics behind it takes a backseat, far behind with nary an attempt.

Neuronal Correlates of Consciousness (NCC) are the minimal set of neuronal events and mechanisms—including synapses, action potentials, neurons, and coalitions of neurons—jointly sufficient for a specific conscious percept. The NCC stands to represent, like an executive summary, selected aspects of the environment—the one you are currently aware of—in a compact manner, to which the organism is trying to adapt to (a microevolution of sorts) and is available for the planning stages of the brain. When the NCC for any percept, for example to recognize a face, is artificially stimulated, say with Transcranial Magnetic Stimulation (TMS) or such, the perception of the face will be created in the mind even when there is no face being seen. Conversely, when some of the face recognition NCC neurons are inhibited, the brain will not be able to recognize the face even when it is right there.

Let me give an analogy. Genes, we know, are the basic unit of heredity. However, to describe the complete characteristics of any individual, nature alone is not enough. The impact of society, culture, environment, and upbringing—i.e., nurture—also plays a big role. Richard Dawkins coined the term memes to describe the basic unit of cultural heredity which influence us. On similar lines, NCC is the minimal unit which describes a conscious percept. NCC are basic units of conscious perception that is constantly happening in our brains.

The book is quite strong on the neuroanatomy of the cortex, specifically focusing on the visual pathways. It describes the retinal structure including the cones and rods, fovea, blind spot, optic nerves, and its connections into the brain regions. He describes the necessity and role of hierarchical arrangement of cortical regions (e.g., LGN, V1, V2, IT, MT, etc.) with feed-forward and feedback connections, as well as the six-layered columnar structure of the cortex, all the time focusing on vision (as it is the most studied senses), but generic enough for other senses too. Alongside, he explains the brain waves and oscillations which Electroencephalogram (EEG) reports show. These background materials are required to research into consciousness, and Koch does a good job of interleaving the descriptions and their relation to the topic on hand, viz. the quest for NCC.

The research strategy to identify the NCC involves relating behavioral correlates of consciousness to the neural mechanisms underlying them. Human subjects can be used, but access to their brains is limited to fMRI or via cooperating patients of brain surgery and strokes. Koch also explores the role of anesthesia on consciousness and as a tool to search for NCC but drops it due to inability in precisely delivering it to targeted areas in the brain. Lab experiments conducted on monkeys’ visual consciousness, mice’s tactile senses, and optical illusions (e.g., yellow dots, Gestalt illusions), are commonly used to track the NCC. The roles of diseased and lesioned brains such as strokes, epilepsy, object agnosia, blindsight, sleep walking, etc., in tracking consciousness are sad and interesting at the same time and contribute immensely to study of consciousness. Much of the book describe the results of these experiments and analyses with copious references to scientific literature.

Taxonomy of memory types—short term, long term, and fleeting memories—is one of the nuggets I got from this book. Most of our actions—referred to as zombie-actions—are in fact non-conscious and they don’t make use of memory. We drive non-consciously, we play tennis and music non-consciously, walk, cycle, saccade, and so on without being aware of them. Zombie agents are generally fast acting, unlike conscious perception which takes time to build-up, and without any extraordinary sensations. The moment we pay attention to such zombie-actions—imagine jumping on small rocks while crossing a stream but stopping to analyze the next jump—we run the potential of losing them, and the action could fail. Based on this, Koch recommends a Turing test for consciousness. If a delay is introduced into a zombie action by using a distraction—i.e., forcing the subject to pay attention which is a conscious action—a working memory is established, and the zombie action is destroyed. A working memory (short term memory), therefore, can be used as a Turing test to recognize a zombie action vs. a conscious one. I.e., an organism with working memory is likely to be conscious although the opposite if not true; a man whose working memory is not intact can still be aware but unable to talk about it afterward. In addition, Koch concludes that consciousness does not depend on long term episodic memory, and that fleeting memory (the kind that results in persistence of vision, lasting for less than a second) could trigger NCC. The fleeting memory is the result of an afterglow in the neuronal substrate left behind by the net-wave of spiking electrochemical activity that can, when appropriately amplified by feed-forward and feedback loops in the cortical regions, lead to a persistent perception via the NCC.

Koch also talks about time synchronization of conscious events. When we see a car coming towards us, the conscious percept of motion, of color, of orientation, of sound, etc., are distinct and yet we see a single, whole car coming towards us. In fact, each percept is thought to happen in discrete moments in time. Yet the various NCCs corresponding to the various percepts fuse together to provide a unitary perception and not wavy stills. How does this “binding” happen? He explores a few oscillations of the EEG (gamma band, with frequencies 30 Hz or more) to possibly explain such synchronization linked to cognitive operations but their role in detecting the NCC is neither clear nor very promising. The colloquial name of 40 Hz oscillation comes from the discovery of such gamma oscillations in rabbit’s olfactory system.

Ultimately, the book is about the ongoing quest. The only strong conclusion he makes, as strong as empirical evidence can provide, and contingent upon the neuroanatomy of visual system, is that none of the vision NCC is in the LGN or the V1 regions of the brain. Where they are, is still speculative and up in the air (thalamus, prefrontal cortex, inferior temporal cortex, medial temporal lobe?). Nevertheless, Koch provides a set of hypotheses and speculations where they could be found, a table of necessary conditions for NCC neurons for any percept, and experiments to test them. Some empirically supported characteristics of the NCC—e.g., that NCC are indifferent to blinks and saccades of the eye—are sprinkled along the way. Binocular rivalry (e.g., hole in the hand illusion; when the left and right eye are supplied with different objects, our consciousness jumps in to choose one or the other; how?) and flash suppression (image presented to one eye is suppressed by a flash of another image presented to the other eye, again a conscious, attention-grabbing event; how and where does it happen?) are promising tools to distinguish neurons that slavishly follow the physical input from those that correlate with the subjective percept, the NCC neurons.

Split brains are another tool to track NCC. Split brains personalities are difficult to sustain, even with the hemibrains completely separated, because our brains are quick to adapt. However, with diligence, neuroscientists can stimulate and probe the hemibrains for NCC. The left and right hemibrains are symmetric only topographically but not functionally. For example, the NCC of speech and writing is in the left hemibrain whereas visualizing that object happens in the right. How then, is the integration achieved in an intact brain? How does the NCC get modified? All interesting questions, and no answers yet.

Koch has tried to stay away from the role of emotions, moods, and language towards perceptual consciousness, which is OK. We have enough to unravel even without them. Many researchers think that language and consciousness coevolved in humans. Language is a big contributor to consciousness and Koch alludes to it when he talks about qualia as symbols. Language experts sweat over the tetradic relation, “How can word ‘ball’ actually mean the real ball out there?” This tetradic is a combination of Relation of Identity between the symbol (‘ball’) and object (one of tennis ball or a soccer ball, or an elongated football, or even snowball), and the Relation of Intersubjectivity (understanding) between human-1, and human-2. When a NCC is setup in the brain and a percept of consciousness occurs, this NCC goes on to trigger other associated neurons that are part of more NCCs—what he refers to as the penumbra of the original NCC—in other parts of the brain. Koch identifies that the qualia is a symbolic representation of these downstream neurons and NCCs and stands to represent them collectively (just like how ‘ball’ does for the balls, or how a red light means stop) and stirs a feeling or an emotion in us and gives meaning, or aboutness or intentionality, to the original NCC. We don’t know how to connect the feeling to physical brain, but the qualia—the symbol—is very real, as real as the word ‘ball’ means the ball. The issue is amplified, nay infinitized, because each one’s life experience is not just different, but our symbolic languages are deficient to accurately express our (private) feelings. Each of us is a unique individual, sincerely thinking we are correct while all others are wrong.

Gerard Edelman, also a Nobel Laureate like Francis Crick, has proposed a Theory of Neuronal Group Selection (TNGS) for consciousness wherein he identifies three levels of consciousness, namely, here and now, experiential, and conceptual categorization, and refers to hierarchical cortical regions whose reentrant connections change as the organism adapts to ever occurring new situations, in a microevolution of sorts. Crick and he had disagreement when Edelman first proposed it, but it appears that the essence of the theory is accepted because many ideas in Koch’s book are like Edelman’s, although this book is not about a theory of consciousness but the neurobiology of consciousness.

This book advocates an excellent scientific approach—not a philosophical, handwaving attitude—to consciousness, with solid, hands-on practices to bridge the gap between the material body and conscious mind, epitomized by René Descartes’s dilemma of duality—the separation of the mind and body.

[Yilmaz Aksoy · Rating 4 out of 5]

Oldukça zor bir konuda yer yer aşırı teknik bir kitap. Anatomi ve biyoloji eğitimi almayınca olayın sadece beyinde geçtiğini anlayabildim. Aslında kitapta yeterince şekillere yer verilmiş ama bunları 200 sayfa sonra yeniden hatırlamak zor. Geri dönüp bakmaya da üşendim. Belki ileride, e-book readerlarda en azından, bu tür animasyonlu, resimli hızlıca çağrılabilen fonksiyonlar koyarlar da bu tür kitaplar çok daha rahat okunabilir.
Canlılarda bilincin nerede ve nasıl oluştuğunu görme duyusu üzerine anlatmaya çalışan bir kitap bu. Bu alanda bir çok şey çok yeni olduğundan burada da genelde sadece kendi (yazar ve çalışma arkadaşı Francis Crick, evet DNA'nın yapısıyla Nobel ödülü alan biliminsanı) hipotezlerinden bahsediyor. Görme duyusunda ilerledikçe spekülasyonların miktarı da artıyor haliyle.
Ben kitabı popüler bilim kitabı beklentisiyle okudum (bence değil) ve bazı şeylerden rahatsız oldum. Mesela bir sürü dipnot ile geçiştirilen açıklamalar. Her bölümün arkasında da bu dipnotların referansları var ama e-book readerda sıçraya sıçraya okumak hoşuma gitmiyor. Ayrıca dipnota gitmek de yetmiyor, çünkü bazen o dipnot sadece yapılan deneyin anlatıldığı bir çalışmaya referans oluyor.
Başka bir rahatsızlık veren nokta da hayvanlar üzerinde yapılan deneyler ve uzun bir süre daha bu deneylerin devam edeceği öngörüsü.
Kitap belli bir rotayı takip eden bölümlere ayrılmış. Ya ben başta bu rotanın tanıtıldığı yeri kaçırdım ya da yazar bundan hiç bahsetmedi. Rota aslında anlaşılıyor ama neden o şekilde incelendiği anlaşılmıyor bence. En azından yaptığı yolculuğun metodik çerçevesini başlarda verse iyi olurdu.
Bu kitap benim için cevapladığı sorulardan çok yeni soruların kaynağı oldu. Daha yeni sayılabilecek bir araştrıma alanı olduğundan bu soruları bilmek bile benim hoşuma gitti. Biraz daha popüler bir dille ve üslupla yazılabilse güzel olurdu ama o zaman da iki kat filan kalınlıkta olurdu heralde.

[Samuel Moss · Rating 5 out of 5]

A spectacular book. Koch is an excellent writer and he structures this challenging material in such a way as to make it totally accessible. He takes a stab at a topic that most neuroscientists shy away from. He makes it very clear what is grounded in evidence (most of the book) and what is speculation. Even then, his speculation follows often times directly from the evidence.

The sort of book which might inescapably alter the way that you understand your own perception of the world (at least this happened to me, in small ways, when I was reading it).

I would recommend this to anyone with an interest in consciousness, anyone with an interest in neuroscience, anyone, really.

[Leonardo]

...muchos investigadores consideran estar frente a un camino prometedor para descubrir de qué manera el cerebro causa la conciencia.

La mente Pág.196

[Derekhadam.com.au · Rating 5 out of 5]

An excellent overview of brain science and a good explanation of Integrated Information Theory.

[Arnold · Rating 4 out of 5]

Excellent description of searching for an elusive spiritual place in our bodies.

[Devin Belden · Rating 5 out of 5]

Dense reading for a layman. An illuminating view into the intricacies of the process of being conscious.

[Arkadiusz Ciosek · Rating 5 out of 5]

Not so easy, but worth. Very interesting

[Robert Więckowski · Rating 4 out of 5]

For me, the book is a 4.5-star read.

[Gert Ouwersloot · Rating 3 out of 5]

Unmistakingly a very scholarly and scientific thorough study of the working of the Brain. But too much grounded in neurobiology, causality, physics and a materialistic stance to be of any use for contributing to the knowledge about phenomenal consciousness. And disturbingly strange how many sentences contain contain words like: could, maybe, perhaps, probably, may, suggest, likely, might, would, not proven, can, is possible, and so on. Scientifically properly cautious, but in fact saying nothing substantial.

[Billie Pritchett · Rating 3 out of 5]

Christof Koch's Quest for Consciousness is intended for lay audiences, but it is still a highly technical book, about the neurobiological approach to investigating consciousness. The book is at turns highly readable and at other other turns abstruse in its use of neuroanatomical descriptions of brain regions and processes. Nevertheless, it was enjoyable to read. Koch argues that consciousness, or awareness, is an emergent property of the nervous system, important for planning and choosing among different action courses. Its function, he writes, is "to summarize the current state of the world in a compact representation and make this 'executive summary' accessible to the planning stages of the brain" (305). Some more counterintuitive suggestions in his work include the claim that a majority of human thought is not consciously accessible and that the feeling human beings have of conscious control is just the frontal lobe sending signals to and from the back of the cerebral cortex. Whatever you think about his conclusions, he makes an interesting case in this book for a more detailed analysis of the neurophysiology of consciousness. I would recommend the book for anyone interested in the mind.

[Jafar · Rating 3 out of 5]

So much neurobiology that the quest for consciousness gets lost in it.

[Jrobertus]

koch worked with crick on neurobiology and the consciousness of vision. they want to define and ncc, a minimal neuronal correlate of consciousness. ok book, but not the best in the field.

[Chadfogg · Rating 4 out of 5]

He never gives up. Nice intro to stages of occipital lobe.

[Katy]

Meant to be reviewed for my senior thesis. heh. This is the continuation of work Koch did with Francis Crick on the nature of the workings of the human mind.

Absolutely fascinating.

[M.D. Backes · Rating 5 out of 5]

By far, my favorite book on brain studies. Focuses on the neural correlates of consciousness.

[Huyen · Rating 3 out of 5]

misleading title, should be Vision and Consciousness or something like that. quite dry and technical, but informative and occasionally very interesting.

[Stelepami]

Read an article in SciAm, was really looking for his upcoming book, but it's not in the database and I'm on mobile.