FOR CENTURIES, the fleeting and highly subjective world of feelings was the purview of philosophers. But during the past 30 years, Antonio R. Damasio has strived to show that feelings are what arise as the brain interprets emotions, which are themselves purely physical signals of the body reacting to external stimuli.

Born in 1944 in Lisbon, Portugal, Damasio has been chair of the University of Iowa's neurology department since 1986. He and his wife, neurologist Hanna Damasio, have created one of the world's largest databases of brain injuries, comprising hundreds of studies of brain lesions and diagnostic images. As profound as some of the damage is to Antonio Damasio's patients, all of it informs his understanding of how emotions and feelings arise and how they can affect mental illness.

In recent years, Damasio has become increasingly interested in the role emotions play in our decision-making processes and in our self-image. In several widely popular books, he has shown how certain feelings are cornerstones of our survival. And today he argues that our internal, emotional regulatory processes not only preserve our lives but actually shape our greatest cultural accomplishments.

—Interview by Manuela Lenzen

MIND: Professor Damasio, why are you so fascinated by the nature of human emotion?

Antonio R. Damasio: At first I was interested in all types of neurological injuries. If one area of the brain would lose its ability to function, the patient's behavior could change either dramatically or only subtly. One day I asked myself, What is missing in a person who can pass an intelligence test with flying colors but can’t even organize his own life? Such patients can hold their own in completely rational arguments but fail, for example, to avoid a situation involving unnecessary risk. These kinds of problems mainly occur after an injury to the forebrain. As our tests prove, the result is a lack of normal emotional reactions. I continue to be fascinated by the fact that feelings are not just the shady side of reason but that they help us to reach decisions as well.

MIND: You differentiate between feelings and emotions. How so?

Damasio: In everyday language we often use the terms interchangeably. This shows how closely connected emotions are with feelings. But for neuroscience, emotions are more or less the complex reactions the body has to certain stimuli. When we are afraid of something, our hearts begin to race, our mouths become dry, our skin turns pale and our muscles contract. This emotional reaction occurs automatically and unconsciously. Feelings occur after we become aware in our brain of such physical changes; only then do we experience the feeling of fear.

MIND: So, then, feelings are formed by emotions?

Damasio: Yes. The brain is constantly receiving signals from the body, registering what is going on inside of us. It then processes the signals in neural maps, which it then compiles in the so-called somatosensory centers. Feelings occur when the maps are read and it becomes apparent that emotional changes have been recorded—as snapshots of our physical state, so to speak.

MIND: According to your definition, all feelings have their origin in the physical. Is that really the case?

Damasio: Interestingly enough, not all feelings result from the body's reaction to external stimuli. Sometimes changes are purely simulated in the brain maps. For example, when we feel sympathy for a sick person, we re-create that person's pain to a certain degree internally. Also, the mapping of our physical state is never completely exact. Extreme stress or extreme fear and even physical pain can be dismissed; the brain ignores the physical signals that are transmitting the pain stimulus.

MIND: The differentiation between emotions and feelings brings to mind 17th-century philosopher René Descartes’ idea of dualism—that the body and mind represent autonomous systems. But you reject that idea, as you explain in your book Descartes' Error. How should we see the relationship between mind and body?

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Damasio: To me, body and mind are different aspects of specific biological processes. Philosopher Baruch Spinoza supported views similar to mine, regarding the body and soul question, shortly after Descartes’ time. In his Ethics he wrote: “The object of the idea which constitutes the human mind is body.” Spinoza thereby anticipated the findings of modern neurobiology.

MIND: Indeed, in your latest book, Looking for Spinoza, you describe the man as “a mental immunologist developing a vaccine capable of creating antipassion antibodies.” So is only a life free of passions a good life?

Damasio: Spinoza fascinates me not only because he was ahead of his time with his ideas on biology but also for the conclusions he drew from these ideas about the correct way to live life and set up a society. Spinoza was a very life-affirming thinker. He recommended contrasting the negative emotions such as sadness and fear with joy, for example. He understood this kind of practice as a way to reach an inner peace and stoic equanimity.

MIND: What are some of the other functions that feelings have, in addition to helping us make decisions?

Damasio: My interest now extends way past the question of decision making. In our lab, we are working more intensely with social feelings such as sympathy, shame or pride—they form a foundation for morality. Neurobiol-ogy doesn’t simply help us to better understand human nature but also the rules of social interaction. Yet to really grasp this, we need a broader research approach: along with cognitive and neurological sciences, many of the humanities could contribute, especially anthropology and sociology.

MIND: It seems your research also extends into defining consciousness. What role do emotions play? What role does the body play?

Damasio: Consciousness, much like our feelings, is based on a representation of the body and how it changes when reacting to certain stimuli. Self-image would be unthinkable without this representation. I think humans have developed a self-image mainly to establish a homeostatic organism. The brain constantly needs up-to-date information on the body's state to regulate all the processes that keep it alive. This is the only way an organism can survive in an ever changing environment. Emotions alone—without conscious feelings—would not be enough. Adults would be as helpless as babies if they suddenly lost their self-image.

MIND: Animals also must possess consciousness, then?

Damasio: I do believe that animals develop a very basic self-concept—what I refer to as “core self.” But to have a broader self, such as we do, requires an autobiographical memory.

MIND: Do you believe that we will someday be able to create artificial consciousness and feelings?

Damasio: An organism can possess feelings only when it can create a representation of the body's functions and the related changes that occur in the brain. In this way, the organism can perceive them. Without this mechanism there would be no consciousness. It is unclear that this could ever develop in a machine or whether we really want machines with feelings.

MIND: Will research on emotions help lead to better forms of therapy for psychiatric illnesses?

Damasio: Without question. Emotional disorders form the core of most psychological illnesses—a good example of this is depression. Specific treatments will be developed in the future, such as new types of medicine that target distinct cellular and molecular systems. Other forms of therapy are also sure to benefit, from traditional psychotherapy to social intervention.