54 internautes sur 58 ont trouvé ce commentaire utile
Michael M. Halassa
- Publié sur Amazon.com
In this new book, Gerald Edelman continues his intellectual saga regarding the scientific study of consciousness. Both the Theory of Neuronal Group Selection (TNGS) and the Dynamic Core Hypothesis have been introduced in earlier books (Surprizingly, with alot more mathematical detail), but never had they been described with clarity and vividness as they were in this book. Examples, that the general reader can relate to, are given throughout the whole book.
Chapter One (The Mind of Man: Completing Darwin's Program) is an assertion by Dr. Edelman that any theory of consciousness should account for the phenomenon to have arisen in evolution by Natural Selection.
Chapter Two (Consciousness: The Remembered Present). This is a chapter in which Dr. Edelman talks about some properties of consciousness in light of William James' earlier descriptions. He ascribes privacy, differntiation and intergration to consciousness and stresses the fact that consciousness is a process not a "thing". For instance, on page 6 he says:
"... there are accounts that attribute conscoiuness specifically to nerve cells (or consciouness neurons) or to particular layers of the cortical mantle of the brain. The evidence, as we shall see, reaveals that the process of consciousness is a dynamic accomplishment of the distributed activities of population of neurons in many different areas of the brain."
Chapter Three (Elements of the Brain) is where Dr. Edelman briefly goes over the structural elements of the brain, describing neurons and their chemical and electrical based signaling systems along with diagrams. He also describes the next hierarchial system of networks and highlights three major neuroanatomical systems that are important for his Global theory of consciousness. Those are the thalamocortical system, cortical/subcortical polysynaptic loop systems (e.g. basal ganglia), and the ascending value system arising from nuclei in the brainstem. It is worth noting that this structural organization is in good agreement with Bernard Baar's Global Workspace model. Another point worth mentioning in this chapter is Edelman's view of synaptic plasticity in relation to memory. on page 21 he says, "Studies of the neural properties of the hippocampus provide important examples of some of the synaptic mechanisms underlying memory. One such mechanism, which should NOT be equated with memory itself, is the change in the strength, or efficacy, of hippocampal synapses that occur with certain patterns of neural stimuation."
Chapter Four (Neural Darwinism: A Global Brain Theory) is a superb chapter. Although, conceptually, TNGS has already been built in earlier books and publications, but it is now vividly described. Dr. Edelman highlight major differences between the working of the brain as a selectional biological systems and that of a Turing Machine. He discusses noise in biological systems, degeneracy, and reentrancy. Degeneracy in relation to Reentrant circuits is finally illustrated in a diagram.
Chapter Five (The Mechanism of Consciousness) is where Dr. Edleman talks about non-representational memory of biological systems (a difficult concept made simple). He also describes the emergence of primary consciousness On page 57 as " The ability to create a scene by such reentrant correlations between value-category memory--reflecting earlier categorizations--and similar or different perceptual categories is the basisfor the emergence of primary consciousness."
Chapter Six (Wider than the Sky: Qualia, Unity, and Complexity) discusses the aformetioned issues along with concepts like information exchange accross brain areas stressing the role of consciousess in them.
Chapter Seven (Conscoiusness and Causation: The Phenomenal Transform) discusses the place of consciousness in the physical world. Dr. Edelman introduces C and C' notions, and explains the logical impossibility of zombies (introduced by David Chalmers).
Chapter Eight (The conscious and the Nonconscious: Automaticity and Attention) discusses the role of consciousness in behavior, and the evolutionary advantage of having a conscious system over automatic (zombie) systems. Dr Edelman also discusses the role of basal ganglia in mechanisms of attention (which are strongly associated with conscious thought).
Chapter Nine (Higher-Order Consciousness and Representation) discusses the role of symbolic/semantic thought in the emergence of higher order consciousness. It also talks about the semantic problems with ascribing representation to neural states that could be observed from a third person perpective, and provides evidence that the neural correlates of consciousness (for a laboratory task at least) are distinct in different people.
Chapter Ten (Theory And Properties Of Consciousness) puts it all together. A superb chapter describing General, Information, and Subjective featres of conscious states in light of all the arguments made earlier. It is the intellectual climax of the book.
Chapter Eleven (Identity: The self, Mortality, And Value) and Chapter Twelve (MInd and Body: Some consequence) describe some scientific and philosopical consequences to the neurobiologic framework of consciousness the book makes. There are some really interesting thoughts regarding value and law.
Overall, this is a great book. The scientific american book review (which is shown on the book description page) is, in my opinion, very poor. If this book was made longer, discussed the ideas more, and showed more experimental evidence (and maybe more math in the Appendix), it would arguably be the best book on consciousness ever written.
36 internautes sur 40 ont trouvé ce commentaire utile
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I was disappointed by this book. I have read a number of recent works on consciousness, and in them I've seen quite a few positive references to bioscientist Gerald Edelman. Philosopher John Searle, who some regard as the "dean" of the consciousness debate, says that Edelman may understand the physical and functional workings of the human brain better than anyone else (see Searle's The Mystery of Consciousness). Edelman's work regarding the brain's ability to set up ad-hoc looping circuits between the many "maps" within it (i.e., small segments that specialize in a particular task, e.g. the area that identifies colors from visual inputs) is very powerful. It addresses many important questions, such as how we experience things in a unified manner when many different areas of our brain separately process the elements and sub-elements of sight, sound, smell and touch.
Thus, I had hoped that Wider Than the Sky would be Edelman's attempt to unfold his powerful insights regarding brain-mind dynamics before the reasonably educated masses. Unfortunately, Dr. Edelman chose to zip through his important ideas so as to dish out a warmed-over version of philosopher Daniel Dennett's functional materialism. This book should be compared with Steven Pinker's How The Mind Works. Pinker wrote a long book that eventually did what it promised, despite breezy asides about Queen Elizabeth, Lilly Tomlin, Leonard Nimoy and the like. Pinker ultimately stuck to analyzing the processes by which the human brain forwards the interests of the body to which it is attached, within a changing and challenging environment. Pinker remained agnostic to the ultimate question of what consciousness is and what its nature might be. I myself would have preferred it if Edelman had stuck to that script.
Edelman does indeed give the reader a taste of some important concepts regarding the dynamics of the brain. These would include: re-entrant neuron looping between processing areas; neural group selection (or day-to-day Darwinism, the on-going shaping of the "plastic" brain); degeneracy (i.e. the ability to quickly change the looping circuits in a way that responds to new stimuli, but doesn't immediately drop the thought or perception that you were attending to); and "value systems" (a spaghetti-like network of connections originating under the cortex, which in effect spray the brain with mood and mind-altering chemicals such as serotonin and ACH at the right times, helping the body to enforce its basic agenda of survival, reproduction and probably other "higher-order" agenda derived from learning experience). But Edelman doesn't take the time to develop these fascinating ideas with needed examples and analogies, so as to help the lay reader to appreciate what he and his team have discovered regarding brain processes. He's like those "I'm only going to say this once" professors that you try to forget once the semester is over.
Instead of explaining his research, Dr. Edelman leads us up the metaphysical mountain of consciousness, where we sit at his feet as he purifies us of any superstitious, dualistic notions regarding who we are and what it's like to be human. He tells us that consciousness, as we "folk" think of it, is ultimately just a side-effect of material interactions. He explains that qualia is really a function, i.e. the brain's ability to discriminate different portions of a mental image. And he fails to acknowledge those who had put forth similar ideas in the past. It's a shame; Edelman rushes through the really innovative research that he is doing, to dwell on a set of ideas that you could get the hang of in an hour or two from one of those Totem / Icon "comic books" (i.e., Introducing Consciousness by D. Papineau and H. Selina).
Edelman takes some other interesting positions, but fails to alert the reader as to their speculative and controversial nature (I mean, isn't that what footnotes are for?). Regarding emotions and feelings, he gives them minimal consideration, passing them off as a side-effect of value system operations (those mind chemicals, remember?). By contrast, some mind analysts such as Antonio Damasio and Susan Greenfield give emotions top-billing. Edelman dismisses the notion advanced by Jerry Fodor that the mind uses a "language" of sorts between its specialty components, and the related notion regarding proto-language, which underlies Chomsky's views about the universal elements of all human languages. I can't say that Edelman is wrong here, but a footnote acknowledging the existence of differing viewpoints seems to be the usual practice. Are Nobel Prize winners permanently excused from the need to footnote?
One more example of Dr. Edelman's intellectual rope-walking without a net: he posits that the human brain has greater computing capabilities than the hypothetical "Turing Machine", which is an intellectual keystone of computing theory. This sounds OK until you do a search on the topic and discover "hypercomputation", a very uncertain and controversial concept. I'd venture that Dr. Edelman is wandering quite far from the zone of expertise where he earned a Nobel Prize (regarding his work in immunology). The same applies to his metaphysical (or anti-metaphysical) admonitions regarding "folk understanding" of human consciousness. His thoughts would make for a lengthy and interesting footnote, for sure. But this book is not about footnotes - it has none (although it does contain a very useful glossary). Wider Than the Sky is another unfortunate example of a brilliant person doing some very interesting research about the brain, who gives in to the temptation of lecturing mere mortals regarding their unenlightened assumptions. I hope that Dr. Edelman came closer to the Pinker tradition of exposition and respect for the general audience in his (Edelman's) other popular works (Bright Air, Brilliant Fire and Second Nature). But I'm not in any hurry to bet on it -- too many other interesting authors on the mind and consciousness to get to.
16 internautes sur 17 ont trouvé ce commentaire utile
Stephen A. Haines
- Publié sur Amazon.com
Exploring the mechanisms of being human inevitably leads us to the mind and its workings. Gerard Edelman has engaged in making those discovery journeys for many years. His stack of published works must stand many centimetres in height. Yet he has been able to distil all that accumulated material into a brief, highly informative book well designed for the general public. That is a stupendous task, yet he's achieved it admirably in this excellent book. In this presentation of human consciousness, Edelman sweeps away much of the mystery. There have been many books attempting to explain our perception of the world. A number of them actually result in a more obscuring than enlightening presentation. Not so in Edelman's case.
Using an Emily Dickinson poem to establish the framework for his thesis, the author declares that consciousness resides in the physical brain. We must understand how that developed, Edelman asserts. The answer, of course, lies in the evolutionary development of the human brain and how that led to our version of consciousness. He stresses that we must not discount the cognitive abilities of other animals. Theirs hasn't achieved the complexity of the human mind, but there are countless hints from theirs as to how ours works. The development of human consciousness is a process, not something granted to us. Much of the process occurs in early life, but whether increasing or growing impaired with age, the process never ceases. Given that condition, Edelman rejects the proposition that the brain is a computer, a structure far too rigid to be equated with our form of consciousness.
Building maps of the brain has been one of science's lengthy undertakings. As details of where brain functions are located emerged, understanding their links to the body grew. Edelman is quick to point out those "areas" are dominated by identified functions, but far from limited to them. The brain is a highly integrated signalling network - Nature's supreme multi-tasking device. Edelman uses a shorthand term TNGS [Theory of Neuronal Group Selection] to explain the networking process. Some shorthand is required in explaining a system of millions of cells with trillions of connections. The appropriateness of Dickinson's aphorism becomes clear as Edelman details the operations of these extensive networks.
The book is assertedly Edelman's. While he doesn't declare that all the findings on brain science are his, neither does he acknowledge who provided the foundation for some of his insights. References are almost all to William James, American founder of cognitive studies. His "Bibliographic Note" is a clear compromise between a full reading list and a teasing call for further reading. He provides an excellent Glossary, to which the new reader to this field should turn at the outset. A number of representational diagrams are provided to enhance the text. In all, Edelman has accomplished his intention - to describe the underpinning of human consciousness in a way we all can comprehend. [stephen a. haines - Ottawa, Canada]
43 internautes sur 51 ont trouvé ce commentaire utile
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"Wider than the Sky" offers a concise scientific explanation of human consciousness to readers with no previous formal education in neurobiology. It avoids the metaphysical and mystical (what Edelman calls "spooky forces") and clearly explains any technical terms used. A glossary at the back of the book defines words from Action potential to Zombie. ("A hypothetical humanlike creature that lacks consciousness but which, it is erroneously assumed, can carry out all of the functions of a conscious human.")
The author uses the concept of neural Darwinism to suggest how consciousness evolved in mammals by massively increasing the connectivity between the cortical areas of the brain that carry out perceptual categorization and the frontal areas responsible for value-category memory systems. The definition of zombies turns out not to be purely whimsical. Consciousness requires specific neural activity - and where that activity occurs there must be consciousness.
Dr Edelman promises a "deeper insight into issues that are the center of human concern" to any reader willing to make a concerted effort to understand this challenging subject. He delivers wonderfully well on his promise. The conscious brain as described in "Wider than the Sky" is complex, dynamic, variable and unique to humankind.
14 internautes sur 17 ont trouvé ce commentaire utile
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This book is either unremarkable or remarkable, depending on wether you have read Edelmans previous work or not. It is unremarkable to those familiar with Edelmans work because this is nothing more than a short and very simple summary of the theories explained more throughly in his earlier books. It is quite remarkable in that Edelman manages to condense all of his ideas (spanning the neural darwinism trilogy, Bright air, Brilliant Fire, and the superb A Universe of Consicousness) in 120 or so pages. For those who simply do not have the time to work over those other books, this is a grat option, not to mention for the lay reader, and those unfamiliar with neuroscience or philosophy. However, the ideas in question all manage to be more appealing and convincing when read in these other books. I do recomend this book strongly.
Now, inasmuch as this book is just a compendium of Edelmans theories, I will not comment on them, since I did that on reviews of his older books. The theory of neuronal group selection (Darwinian processes in neuronal plasticity), and his theory of consicousness (the remembered present and the dynamic core) are important players in the consciousness debate, without a doubt.
But Edelman also tries to do some philosophizing. This is something scientists studying consciousness tend to do often on their newer books. And it is also the part of these books that open new points for discussion in the consciousness literature. And Nobel prize or not, he does not do it well. Let me explain.
Edelman tries to advance a bridging principle to his neuronal theory of consicousness. That is, he tries to explain the precise relationship of neural states (N) to consicous states (C). And unfortunately it all amounts to a very Searleian property dualism. N entails C, but it is not identical to it, and further, C is and cannot be causal, while N can. Edelman is right in that this is a closed version of materialism. No non-physical properties are claimed to exist. But the relationship is still probematical.
First, there is the very real threat of epiphenomenalism. Edelman denies this, but he is after all claiming that C states are actually epiphenomenal, by his definition. N is not, but C is not identical to N, but entailed by it. Now if liquidity is entailed by the structure of H2O for example, and it is, then it makes sense to say that liquidity itself may have a property that water does not. Liquidity may be uncausal, while water can be causal. But this claim is nonetheless false. Liquidity is causal. It makes water behave in certain ways. So, even if we grant, that if C is entailed by N, means that N can have properties that C does not, this does not guide us to claim which properties these are. That is, Edelman needs other reasons to convince us that C is not causal just because it is entailed by N, that is actually causal. C could be like liquidity. C could be causal, and entailed by N too. N could occur without it causing something that C would cause if it was present, even if C could not be present without N, which is my reading of the use of ¨entail¨. So nothing edelman says has a bearing on the causal status of C.
Edelman sort-of anticipates these arguments, but only claims that the ideas ¨C can occur without N¨ , ¨C is causal ¨, are contradictory. Thay are, only if one takes as undeniable his definitions of ¨entail¨, and his ideas of the relationship of C and N. Edelman assumes he is right to prove he is right. The epiphenomenalist considerations I wrote of, are a little shaky, however. But Edelmans position falls fast when other more mysterian arguments are noted. If C is only entailed by N, but not identical to it, then it is very much logically posible that N could exist without C, and everything in the neural economy be identical. Edelman argues against this possibility, a posteriori, by pointing out that evolution made the relationship between C and N necessary. So his idea is that because N and C evolved, yhey are so related, not that because they are so related, they could have evolved. This is again assuming he is right to show he is right.
One could continue endessly. What makes some N entail some C and not another? If N entails C, would a minimally and disembodied N still entail a full C? If C can be caused, why can it not cause back? Any philosoher could come up with his own objection. So in conclussion, Edelman is on the right track, but as lost as many a scientist as to how to intellegebly bridge the neural states to the conscious states. Maybe philosophers will be essential to the search for the neural bases of consicousness after all.