The Quest for Consciousness: A Neurobiological Approach (英語) ハードカバー – 2004/3/1
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Born in 1956 in the American Midwest, Christof Koch grew up in Holland, Germany, Canada, and Morocco, where he graduated from the Lycèe 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.
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.
While I found the book intersting to read I was not very satisfied at the end of it. A savannah of philosophical questions are simply overlooked. Secondly, many paragraphs and arguments are prefixed with the phrase 'Francis and I...' This was entirely unnecesary and suggested either grandiosity or else a thinness of argument that needed the heft of the fame of a historical figure to get it through the door. It would be very intersting to read another edition of this book where more weight was given to the philosophical and computational conundrums that accompany eliminativist thinking. Despite these reservations, it is a book worth musing over.