Descartes' Error: Emotion, Reason, and the Human Brain (Anglais) Broché – 27 septembre 2005
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Phineas P. Gage
It is the summer of 1848. We are in New England. Phineas P Gage, twenty-five years old, construction foreman, is about to go from riches to rags. A century and a half later his downfall will still be quite meaningful.
Gage works for the Rutland & Burlington Railroad and is in charge of a large group of men, a "gang" as it is called, whose job it is to lay down the new tracks for the railroad's expansion across Vermont. Over the past two weeks the men have worked their way slowly toward the town of Cavendish; they are now at a bank of the Black River. The assignment is anything but easy because of the outcrops of hard rock. Rather than twist and turn the tracks around every escarpment, the strategy is to blast the stone and make way for a straighter and more level path. Gage oversees these tasks and is equal to them in every way. He is five-foot-six and athletic, and his movements are swift and precise. He looks like a young Jimmy Cagney, a Yankee Doodle dandy dancing his tap shoes over ties and tracks, moving with vigor and grace.
In the eyes of his bosses, however, Gage is more than just another able body. They say he is "the most efficient and capable" man in their employ.- This is a good thing, because the job takes as much physical prowess as keen concentration, especially when it comes to preparing the detonations. Several steps have to be followed, in orderly fashion. First, a hole must be drilled in the rock. After it is filled about halfway with explosive powder, a fuse must be inserted, and the powder covered with sand. Then the sand must be "tampedin," or pounded with a careful sequence of strokes from an iron rod. Finally, the fuse must be lit. If all goes well, the powder will explode into the rock; the sand is essential, for without its protection the explosion would be directed away from the rock. The shape of the iron and the way it is played are also important. Gage, who has had an iron manufactured to his specifications, is a virtuoso of this thing.
Now for what is going to happen. It is four-thirty on this hot afternoon. Gage has just put powder and fuse in a hole and told the man who is helping him to cover it with sand. Someone calls from behind, and Gage looks away, over his right shoulder, for only an instant. Distracted, and before his man has poured the sand in, Gage begins tamping the powder directly with the iron bar. In no time he strikes fire in the rock, and the charge blows upward in his face.
The explosion is so brutal that the entire gang freezes on their feet. It takes a few seconds to piece together what is going on. The bang is unusual, and the rock is intact. Also unusual is the whistling sound, as of a rocket hurled at the sky. But this is more than fireworks. It is assault and battery. The iron enters Gage's left cheek, pierces the base of the skull, traverses the front of his brain, and exits at high speed through the top of the head. The rod has landed more than a hundred feet away, covered in blood and brains. Phineas Gage has been thrown to the ground. He is stunned, in the afternoon glow, silent but awake. So are we all, helpless spectators.
"Horrible Accident" will be the predictable headline in the Boston Daily Courier and Daily Journal of September 20, a week later. "Wonderful Accident" will be the strange headline in the Vermont Mercury of September 22. "Passage of an Iron Rod Through the Head" will be the accurate headline in the Boston Medical and Surgical Journal. From the matter-of-factness with which they tell the story, one would think the writers were familiar with Edgar Allan Poe's accounts of the bizarre and the horrific. And perhaps they were, although this is not likely; Poe's gothic tales are not yet popular, and Poe himself will die the next year, unknown and impecunious. Perhaps the horrible is just in the air.
Noting how surprised people were that Gage was not killed instantly, the Boston medical article documents that "immediately after the explosion the patient was thrown upon his back"; that shortly thereafter he exhibited "a few convulsive motions of the extremities," and "spoke in a few minutes"; that "his men (with whom he was a great favourite) took him in their arms and carried him to the road, only a few rods distant (a rod is equivalent to 5 1/2 yards, or 16 1/2 feet), and sat him into an ox cart, in which he rode, sitting erect, a full three quarters of a mile, to the hotel of Mr. Joseph Adams"; and that Gage "got out of the cart himself, with a little assistance from his men."
Let me introduce Mr. Adams. He is the justice of the peace for Cavendish and the owner of the town's hotel and tavern. He is taller than Gage, twice as round, and as solicitous as his Falstaff shape suggests. He approaches Gage, and immediately has someone call for Dr. John Harlow, one of the town physicians. While they wait, I imagine, he says, "Come, come, Mr. Gage, what have we got here?" and, why not, "My, my, what troubles we've seen." He shakes his head in disbelief and leads Gage to the shady part of the hotel porch, which has been described as a "piazza." That makes it sound grand and spacious and open, and perhaps it is grand and spacious, but it is not open; it is just a porch. And there perhaps Mr. Adams is now giving Phineas Gage lemonade, or maybe cold cider.
An hour has passed since the explosion. The sun is declining and the heat is more bearable.
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The case studies of sensory agnosia were very interesting, especially the one where the patient had apparently lost the functioning of the part of his brain that stored the awareness of one side of the patient's body, to the point where the patient had no awareness or perception of that half at all, and even denied that he even had a problem with it. There can be no clearer demonstration of the fact that our consciousness and awareness depends entirely on that 3-pound, convoluted mass of nerve cells we call the brain.
As someone with a pretty fair background in the area myself (I did a master's and almost completed a Ph.D. in psychobiology) I can vouch for Damasio's command of the scientific and technical issues and details (notwithstanding that fact that Damasio is both an M.D. and a Ph.D.) so he has a good command of the medical issues also. The book is very well written, although not easy, but Damasio does a fine job of explaining the more difficult ideas.
One further comment, I read one review that was critical of Damasio for supposedly misinterpreting Descartes's dictum, "I think, therefore I am," and then spent the whole review discussing Descartes instead of Damasio's book. The reviewer also stated that because of this Damasio lacks scientific objectivity. Since his comment is itself a good starting point for discussing the most important aspect of Damasio's book, I thought I'd write a little more on it here.
Whether or not Damasio's interpretation of Descartes dictum is wrong or not, (and from the other reviewer's disjointed discussion, that itself isn't very clear), this is a minor detail, since Damasio simply uses this as a point of departure and from there on the vast majority of the book is devoted to a discussion of the neurological and brain issues, not to the technical details of the philosophy of mind-body dualism, for which there are already plenty of other discussions out there (having read many of them myself).
However one should precisely interpret Descartes's famous statement, Damasio is completely correct in pointing out the most important aspect of Descartes's idea--that the mind is fundamentally different from the brain itself and that one needs a dualistic theory to explain the separation of the apparently immaterial mind from the more material body--is wrong.
Although echoes of this theory can still be seen in modern philosophy, and were an important influence on idealist philosophers that followed Descartes, such as Kant, and even continue to have an influence on modern neo-Kantian theory and other thinkers, the advance of modern neurobiology has shown that these theories are fundamentally wrong.
Since we're on the subject--and to be completely fair--I will that say that one aspect of Kant's theory is quite accurate--that the mind is actively involved in organizing the data of the senses--and that ideas about the external world could not exist unless there were corresponding mental capabilities and constucts to match. Our understanding of sensory information processing and of advanced cortical abilities certainly show that the brain has evolved in a way that reflects the need for specific capabilities to enhance our survival in a dangerous world. Kant's idea that there are inborn mental faculties that allow us to form ideas about the external world isn't so different from this idea, and in that sense, Kant was right. (This would have been a good point for the other reviewer to make, but he got lost in the trivial details, and failed to see "the forest for the trees" (as he himself incorrectly said of Damasio)).
Anyway, returning to Damasio's book, this is well-written book on a fascinating aspect of modern neurobiology, and which has profound implications for western philosophies of idealism and dualism. Although not an easy book for the non-specialist, it's worth the effort.
I have one final suggestion to make, and that is you might want to read Michael Gazzaniga's more general introduction to neurobiology: "Nature's Mind: The Biological Roots of Thinking, Emotions, Sexuality, Language, and Intelligence," before tackling this one. It's also an excellent book and you'll have a more well-rounded understanding of the brain field which should stand you in good stead to tackle this book, or any other brain-oriented books, after reading it.
1.) scan sections of the book before and after you read them. The author's simple expositions are terrific but the book's organization and data blending can be confusing, and the pace often slows uncomfortably. 2.) Consider using a good neuroanatomy text or atlas, like Barr or Hanaway. The author's maps are surprisingly skimpy and I strongly hope he includes a few pages of neuroanatomical diagrams in any future editions. 3.) You may want to underline selected terms and definitions, and note the reference at the back of the book -- the book has no glossary and the index is annoyingly weak. 4.) I thought the most valuable sections were on the Somatic Marker Hypothesis, the Body-Minded Brain, and the Postscriptum -- consider scanning these sections as you begin the book.
Good luck and enjoy. The author's credentials are superb, his perspective complements other authors such as Edelmann, William James, and LeDoux, and he brings the unique and empathetic perspective of a neurologist who has specialized in analyzing the changes associated wtih discrete neuropathological conditions. The ideas you may receive from this wonderful book should be well worth the effort, and you should gain some insight into the miracle of how we think/feel/are.
Damasio takes the abstruse and technically demanding field of neuroscience and turns it into a novel. The book is not dumbed down, nor is it patronizing.
Damasio's main contention is that logic and reason are impossible without emotion. That is why intuitions are called gut feelings. He goes over many case studies, experiments, and introspection, to drive this point home.
Our body is where the action takes place. Only after (or sometimes concurrent with) the body makes up its mind, does the mind follow. For a quick example, suppose you are sitting down in a college classroom. There is an open seat next to you. Suddenly, you spot a voluptuously delightful young lady walking toward you. What happens to you? Your heart starts to beat faster, your palms sweat a little, your body tenses up; and neurotransmitters release a cascade of chemicals into your blood stream which modulate your body's internal viscera. You focus your attention on this women. Do you invite her to sit next to you? Or, are you to nervous to do so? If you are too nervous, think about what is going on. Is it because your brain is telling you that you are? No. Your body is sending signals to your brain and vice versa in a feedback loop. Your brain then 'reads' the signals comming from your body as nervousness. Without a body, you could 'feel' nothing. There would be no emotion.
Thus, to a large degree, your decision was made prior to conscious awareness, and you could not control it.
This way of thinking seems anathema to Westerners who love to believe that rationality means pure logic without emotion. You know what happens to decision making when your emotions become blunted due to brain damage? It goes completely out the window.
As Damasio says: "No body, never mind."
I think the take home message of this book is that we are biological organisms through and through. There is no Cartesian soul: Nothing that makes humans unique machines of deduction. We are at the mercy of our passions.
This should not be surprising. Great thinkers from Augustine to Hume have suspected as much. Now we have the science to confirm such insights.
N.B. some of the material in this book is dated. Consult Damasio's later books and Journal articles by Ledoux, Damasio et al. For the latest progress in neuroscience.
The first indication of the relationship of the mind and body was the bizarre penetration of a railway worker's skull in 1848. The worker lived, but the damage to his brain left him with severe personality changes. The case opened the door to research leading to mapping areas of the brain that reflected various personality traits. Damasio recounts the incident, matching it with numerous clinical studies of his own. Additional work, some of it strongly innovative led Damasio and his colleagues to a reformulation of how the mind and body interact.
He reminds us that the brain is much more than a collection of electrically interacting cells. The body is sending information to the brain almost continuously, with the brain replying or initiating communication. These signals are both electrical and chemical. More importantly, Damasio reflects on the evolutionary origins of these conditions. For him, it is inevitable that the mind and body interact intimately. His proposed appellation for Emotions aren't separated from our reasoning processes, but are an integral part of them. The attempts by parents and educators to "train out" emotions in children are thus doomed to fail.
Damasio's thesis hinges on what he calls "somatic markers." The markers are areas of the brain which continuously interact with the body, particularly those areas we associate with emotions. If confronted with emotionally charged choices, the stomach "knots," the face may "flush" warmly, and perspiration may increase markedly. These body/brain functions begin developing early in the embryo. Indeed, they have a long evolutionary history, which firmly establishes their roots. In humans, the brain not only controls/reacts with the body in addressing stressful circumstances, but retains some level of memory of the events causing the reactions. Hence, even thinking about such circumstances can lead to bodily reactions associated with them. You need not be confronting an emotional situation to be able to express the feelings associated with it. This, of course, is most notably seen in actors or other performers. Damasio offers the excellent example of orchestra conductor Herbert von Karajan, whose pulse rate was higher while conducting than when confronted with an emergency situation in an airplane. To Damasio, "Descartes' error" was that he placed all these controls in a central location of the "mind" where, in fact, they are scattered over much of the brain.
The implications from this book will be far reaching. Besides impacting academic courses on behaviour, there will be changes in how we parent, how we deal with education, and even in the realm of law. Binding reason and emotion will revise uncountable long-standing ideas about how the mind deals with our surroundings. It is a work addressing fundamental questions about what make us human. Read it with care, aware that many preconceptions are likely to be challenged. The rewards for this effort will be great in years to come. [stephen a. haines - Ottawa, Canada]