"We may never understand exactly why emotion was given the cold shoulder of science for almost 100 years. By the last quarter of the 19th century, Charles Darwin, William James and Sigmund Freud had thought and written brilliantly about the nature of emotion, about the possible biological mechanisms behind it and about the ways in which it could be disturbed. The British neurologist John Hughlings Jackson had even made a first stab at discerning the anatomy of human emotion by planting it in the right cerebral hemisphere. There would have been every reason to expect that the budding brain sciences would concern themselves with emotion in much the same way they had been taking on language or visual perception._________________________________________________________________ ANTONIO R. DAMASIO is the author of Descartes' Error: Emotion, Reason and the Human Brain (G.P. Putnam's Sons, 1994). He is Van Allen Professor and head of neurology at the University of Iowa College of Medicine. _________________________________________________________________"Curiously, it never came to pass. Emotion was consistently left out of the mainstream of what became neuroscience and cognitive science. A handful of psychologists, such as Stanley Schachter of Columbia University, carried on important studies on emotion; psychiatrists and pharmacologists concerned with mood disorders developed and applied drugs that gave indirect information on the mechanisms of emotion. By and large, however, neuroscience and cognitive science neglected emotion until quite recently. In what may have been the last gasp of post-Cartesian and post-Kantian intellectual dryness, emotion was not trusted, in real life or in the laboratory. Too subjective, it was said, too elusive, let's face it, too irrational for the likes of modern science.
"Some of us have long thought this attitude was wasteful, not to say silly, and proceeded as if a field called "neurobiology of emotion" already existed. That missing field was created in the process, and Joseph LeDoux, author of The Emotional Brain, stands out among the creators. At his laboratory at New York University, LeDoux has made a rich contribution to the understanding of one of the star emotions, fear. Working in animals and concentrating on a pivotal brain region known as the amygdala, LeDoux has performed a number of ingenious experiments that throw light onto some of the neural mechanisms of the fear response. Much of what he has discovered is applicable to other emotions and to human beings. It also provides a valuable blueprint for further animal studies.
"The Emotional Brain draws its strengths heavily from the author's own work. There is no substitute for the firsthand knowledge of how the process of discovery unfolds--sometimes exciting, sometimes painful. LeDoux incorporates his experience to produce an account that is informative (for those who may wish to learn about one approach to systems neuroscience), useful (for specialists) and pleasant (for all). The writing is direct, without subterfuge or pretension, and the author even acknowledges colleagues--a duty so rarely observed in science trade books that it should certainly be regarded as a virtue.
"LeDoux frames his account with a well-articulated reflection on the past and future of emotion research. With remarkable courage, he takes on the long-standing controversy over the role of the body in the processing of emotions. This controversy is probably the central issue in the neurobiology of emotion. William James proposed that when the brain triggered emotions they were enacted in the body and that the changes resulting from such an enactment were subsequently represented in the brain and apprehended consciously. A number of critics countered that the essential components of the mechanism occurred within the brain and that body responses were not essential for the feeling of an emotion. Although its arguments were muddled and uninformed, the anti-James camp was the winner, perhaps because the incompleteness of James's framework (inevitable given the limited knowledge of the time) rendered it vulnerable.
"That this state of affairs prevailed until recently can only be explained by subsequent researchers' reluctance to examine the problem in any depth. LeDoux is not shy in his assessment: "It's hard to believe that after all these years we actually still don't have a clear and definitive understanding of the role of body states in emotions. However, I'm placing my bets in favor of feedback playing a role. Emotional systems evolved as ways of matching bodily responses with the demands being made by the environment, and I can't see many ways that a full-blooded emotional feeling could exist without a body attached to the brain that is trying to have the feeling."
"He also replies eloquently to the oft-asked question of the emotional status of tetraplegics who have lesions in the cervical spinal cord (and who therefore have little feeling or motor control below the level of the neck). The continuing ability of tetraplegics to feel some emotion seems to speak against the role of body feedback in emotion. But few, if any, injuries ever destroy the cord completely and thus some body sensory input still goes through. Moreover, a considerable amount of visceral input bypasses the cord altogether and enters the central nervous system at the brain stem level via cranial nerves. Patients with spinal cord lesions do display some changes in emotional processing, a clear witness to the value of on-line body signaling since even partial damage can have an effect.
"LeDoux's argument is completed by my own proposal for an "as-if-body-loop," as presented in my book Descartes' Error. I have suggested, and LeDoux agrees, that some emotional responses can change somatosensory representations in the brain directly, "as if" the latter were receiving signals from the body, although in effect the body is bypassed. People probably have both body-loop and as-if-body-loop mechanisms to suit diverse processing conditions. The critical point, however, is that both mechanisms are body-related.
"I also enjoyed LeDoux's perspective on the closely related argument that the body would not provide enough variety of signals to signify the different emotions we experience. I have pointed out the weaknesses in this argument, and I am pleased LeDoux endorses the idea that body signals can easily provide the diversity of emotional patterns. He writes, "When all the interactions between the various systems are taken together, the possibilities for the generation of emotion-specific patterns of feedback are staggering. This is especially true when considered from the point of view of what would be necessary to scientifically document the existence of these patterns, or, even more difficult, to prove that feedback is not important."
"I do not wish to disappoint readers bored by so much agreement between reviewer and author, so I will say I do not endorse LeDoux's general attitude toward feelings (though I understand well why he holds it). In essence, LeDoux believes the investigative effort in our field should focus on the biological responses that constitute an emotion because these responses can be identified and manipulated in animal experiments, whereas feelings, which are the perception of the emotional responses, can be studied only with the cooperation of the self that experiences them. His fear of feelings is really twofold. On the one hand, animals may have feelings, but we cannot study them effectively. On the other, the "soft" study of feelings was associated in the past with some of the confusion that arose from poorly conceived studies of emotion.
"I disagree, because times and technologies have changed. The modern techniques of cognitive neuroscience allow us to study emotion in animals and both emotion and feeling in humans. The combination of animal and human studies will eventually reveal, in seamless fashion, the continuity of processes that begin with a triggering mind stimulus, proceed to emotional responses and to their sensory representation, and conclude with the conscious readout known as feelings.
"In the meantime, The Emotional Brain is an excellent introduction to the strange history of the neurobiology of emotion and a preview of what lies ahead."
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