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About the Authors:
Gerald M. Edelman, M.D., Ph.D., received the Noble Prize for Medicine in 1972. Director of the Neurosciences Institute and Founder of the Neurosciences Research Foundation, he is the author of Neural Darwinism, Topobiology, The Remembered Present, and Bright Air, Brilliant Fire.
Biulio Tononi, M.D., Ph.D., is a Senior Fellow in Theoretical and Experimental Neurobiology at the Neurosciences Institute. He is the editor, with Olaf Sporns, of Selectionism and the Brain. Both authors live in San Diego, California.
How did you first get involved in this project?
The story of how this book came about begins on a summer night of 1989 in the south of Sardinia. One of us (GME) was retiring to his hotel after a lecture on the brain and an exhausting trip throughout the island. Immediately upon entering the hotel, he was confronted by the other (GT), even more tired but obviously so determined to speak to him that he was allegedly mistaken for a possible assassin. It turned out that he had briefly escaped from his duties as a medical officer in the Italian Army and had crossed the island of Sardinia north to south on a motorcycle. His goal, prompted by reading some of GME's work, was to join him in the adventure of understanding the brain. In the brief conversation that followed, it emerged that both shared, as the central theme of their scientific endeavors, the need to understand consciousness from a scientific point of view. This marked the beginning of a scientific collaboration that lasts to this day. Since that time, they have worked closely together at The Neurosciences Institute, first in New York and then in San Diego, to elaborate a consistent theory, develop large scale computer models adequate to the task of understanding consciousness, and carry out several experimental approaches to the problem of the brain bases of consciousness. This book represents the outcome of these efforts so far and a summary of their journey together.
There is an increasing number of books on consciousness. What is new and special about this book?
Over the last decade, a number of books on the subject of consciousness have appeared. They range in content from philosophical excursions, to theories invoking exotic physics, and finally to psychological "information-processing" descriptions that do not touch upon the relationship between the brain, the mind, and consciousness. Our book takes account of brain processes and new findings. It presents a consolidated scientific theory that tackles the fundamental problem of consciousness in terms of actual brain events in a manner supported by both theoretical studies and experimental evidence on the brain and behavior.
In attacking the problem of consciousness our strategy is unusual. We emphasize the fact that consciousness is a process, not a thing, as was presciently pointed out by the great American psychologist, William James. Instead of being lured by the extraordinary variety of conscious phenomena and trying to explain everything, we concentrate on the general properties of conscious experience. These properties include privateness, unity, and complexity or informativeness, all of which are shared by every conscious state. We then examine what kinds of neural processes can actually explain such properties, rather than just correlate with them. We develop new models, concepts, and measures, the most important of which is a measure of complexity. A major task of our book is to show that consciousness and complexity are intimately linked. Finally, we present a new formulation, the "dynamic core hypothesis", which establishes criteria for determining whether the activity of a group of brain cells does or does not contribute to conscious experience. This hypothesis suggests new ways of considering certain disorders of consciousness representing some of the most mysterious chapters of neurology and psychiatry, such as split brain syndromes, amnesia, hysteria, multiple personalitites, and fugue states.
What is special about the problem of consciousness?
Everyone knows what consciousness is: it is what abandons you every evening when you fall asleep and reappears the next morning when you wake up. This deceptive simplicity hides a problem that has intrigued philosophers for centuries, and as such now presents a formidable challenge to the well-equipped scientists who are confronting it at the end of the millennium. Hard as it is to solve, the fundamental problem posed by consciousness can be illustrated with a simple example. Imagine a dark room with a human being inside who reports whether he sees light or dark. Inside the room is a photodiode, a simple physical device that can also tell the difference between light and dark and provides an audible output. Why should the differentiation between light and dark performed by the human being be associated with the subjective experience of light and dark, while the same differentiation performed by the photodiode lacks such a remarkable property?
Why should the physical events occurring inside a fistful of gelatinous tissue in certain parts of our brain give rise to the phantasmagoric world of conscious experience, a world that contains everything we feel, everything we know, and everything we are - a world that represents, for each of us, everything there is? And why instead should other physical events, such as those occurring in other parts of the brain or inside the silicon chips of a computer, be utterly devoid of the flavor of subjective experience, of those elusive properties that philosophers call qualia? This is the central problem of conscious experience, a problem that Schopenhauer brilliantly termed "the world knot". This problem is what our book is about. In the book, we present our attempt at untying the world knot.
Why have philosophical approaches and previous scientific attempts hit an impasse?
Philosophers have often attempted to understand thinking by thinking alone. While this has served to bring out many of the essential questions about consciousness, it has failed to provide convincing answers or has led to discouraging claims that the problem is hopelessly insoluble. What is hopeless, we believe, is the attempt to provide an equivalent of conscious experience through description alone. Needless to say, this will never happen - having a body counts.
Although scientists have always acted with great circumspection when faced with the mystery of consciousness, something has definitely changed since the late eighties. What is new upon the scene is an extraordinary excitement stimulated by the realization that the study of consciousness is not just the domain of philosophers but is actually a proper subject for scientific study. The result so far has, unfortunately, been a mixed bag. Some good scientific work has emerged, but also a lot of nonsense, examples of which are the calling upon a miraculous form of dualism, in which consciousness is incorporeal and yet communicates with the brain. Others have not denied the material bases of consciousness but have ignored the lessons of brain science and invoked exotic aspects of physics, such as quantum gravity, as a possible solution to the mind-body problem. Finally, many who pay due respect to the way the brain works may still fall into category errors, such as assigning the source of conscious experience to the intrinsic properties of specific local brain areas or even of special brain cells. In our book, we criticize these positions and provide a much more dynamic view of the material basis of mind.
Why should everyone be concerned or even excited by the questions raised in your book?
We believe that the attempt to untie the "world knot" is an exciting adventure that can be shared by the common reader who is willing to spend a bit of effort. By the end of our essay that reader will, we believe, understand how, from relatively simple evolutionary events and brain mechanisms the vast panorama of consciousness arises. This panorama includes those manifestations that are specifically human, such as thought, language, and logic. If the sort of complexity of brain processes described in our book is indeed what makes our consciousness what it is, and if this complexity arises from selectional events during evolution, development, and individual experience, each conscious experience is not only private, unified, and highly informative, but it is also unique. It is at the center of human concern. This is perhaps one more reason to embark on an adventurous journey, one that leads from matter to evolution, thence to the development of brain complexity, from that complexity to consciousness, and from consciousness to imagination.
Can you make any astonishing predictions based on your ideas, and how will their acceptance change human values?
One of the most extraordinary predictions of our model of the brain and mind is that, some day, scientists and engineers will be able to construct a device capable of exhibiting consciousness. While this is in the future, achieving such a goal will have revolutionary implications for human communication and computation, but more importantly will be instrumental in finding out who we really are and thus define our place in the universe. We do not believe that the achievement of this goal will debase our humanity. Instead, it will lead us to appreciate the true basis of our individual natures and personalities. We predict that, at the end of this quest, one of the great problems confronting science - understanding the place of values in a world of facts - may stand for the first time on solid ground.
Posted September 5, 2000
This new volume provides a biologically-based perspective on consciousness. Although Edelman & Tononi may often appear to lead the reader into believing that a `selector' is needed in order for one to choose between the many alternative possible behaviours that one might act out, there is no room for a Humunculus (the little man inside the man `seeing' solutions) of any sort here. For those unfamiliar with Edelman's previous writings (all of which I would recommend) there are plenty quotes from his earlier self, the principle idea here being a logical extension of his thesis developed over the last 20 yrs. Coming clean right from the start, the data acquired from introspection is rejected as a technique to be subjected to any robust empirical analysis, but consciousness is here identified not solely with brain states/activity (there is a clear need for interactions with others and the world `out there') - the authors putting forward a model of consciousness as being a `particular kind of brain process'; unified/integrated, yet complex/differentiated. The early parts of the book discuss the `impasse' reached by many philosophers in their attempts to explain the `mind-body' problem whilst rejecting both strong dualist and reductionist positions: '..consciousness requires the activity of specific neuronal substrates .......... but is itself a process, not an object'. There is a clear appeal to holistic thinking here (`the whole is greater than the sum of its parts') - but the message is more subtle. What Edelman & Tononi are pointing out is that, still in need of explanation is the fact that although the contents of consciousness change continually, its possessor remains continuous. The problem of how one discriminates between our vast repertoire of conscious states (and how one is `selected' for experience in real time from this pool) is the main evolutionary question being addressed. Assumptions are not ignored (reflexes are allowed to operate in certain circumstances), but emphasis is placed upon the integration function of the human brain, rather than the clearly identified anatomical segregations long known to exist. For example, there have been at least 36 different visual areas reported in primate brain, each linked by more than 300 connection/projection pathways, 80% of which have recurrent-colateral or re-entrant connections. These latter findings are the focus of Edelman's developing theory of consciousness. For a long time now, many researchers have come to believe that distinct, distributed patterns of neuronal firing give rise to the integration of perceptual and motor processes - but how such patterns are strengthened to provide routinised behaviour and expertise remains unclear. The data presented with respect to the detailed nerve receptor-level changes re growth and the known pharmacological effects of certain natural transmitter substances and drugs are welcome and well written for the lay person to follow (often lacking in the specialist journals of the field!). However this debate may resolve, Edelman & Tononi are here suggesting that in like process, co-ordinated behaviour (including consciousness) derive from the detailed brain connectivities together with their variability and plasticity over time - especially in relation to the (highly flexible?) dynamics of reentrant connections. How such distributed neuronal firing patterns are `selected' for as `the brain interacts with the body' requires better evidence, but with our current state of knowledge, this is definitely a step in the right direction. From an evolutionary perspective, this is Neural Darwinism writ large, proposing a research agenda entirely consistent with that thesis. For those in the know, there are also (uncited) tributes to Waddington (as in `Epigenetic Landscapes') and support for those working on behavioural robotics and the emergent properties of dynamic systems. The details of the text I will leave to the reader to enjoy - cliniWas this review helpful? Yes NoThank you for your feedback. Report this reviewThank you, this review has been flagged.