Keynote Address"The Science of Emotion"
Antonio R. Damasio, M.D., Ph.D., is the M.W. Van Allen Professor and Head of the Department of Neurology at the University of Iowa College of Medicine, and adjunct professor at the Salk Institute in La Jolla, California. He is the author of Descartes' Error: Emotion, Reason and the Human Brain.
In the last century there was a neuroscience of emotion, and today there is a neuroscience of emotion. In between there was a long, dark gap during which neuroscientists regarded emotion as elusive, objectively difficult to define, and thus, not acceptable to study. Reinforcing this attitude was a long philosophical tradition of not trusting emotions, regarding them as unruly phenomena that can wreak havoc on decision-making.
As recent research has shown, this prejudice and attitude are profoundly wrong. In the very least, we can say that emotion is always in the loop of reason. Emotion is an adaptive response, part of the vital process of normal reasoning and decision-making. It is one of the highest levels of bioregulation for the human organism and has an enormous influence on the maintenance of our homeostatic balance and thus of our well-being. Last but not least, emotion is critical to learning and memory.
Using imaging techniques such as magnetic resonance imaging (MRI) and positron emission tomography (PET) to study patients with brain lesions as well as normal subjects, we have begun to make some inroads into understanding the areas of the brain involved in different types of emotion.
Emotion is a very adaptive form of physiological response, and it regulates our lives. Emotion is expressed largely in the theater of the body, through posture and facial expression as well as through such internal processes as heart rate and blood pressure. Moreover, all of these bodily responses are fed back to the brain through neural channels as well as humoral channels, which bypass neural signaling.
To understand how emotion works on the body, we must differentiate emotion from feeling. When we experience any of the primary emotions--sadness, happiness, anger, fear, surprise, disgust--our experiences express themselves physically, in ways that can be observed by another person.
Feelings, by contrast, are our conscious perception of all those changes happening in the body, and of very subtle changes that are happening in the way our cognitive apparatus functions.
Most of what happens when an emotion is elicited happens nonconsciously. Often our body may already be in a state that represents anger before we know what is making us angry. The creation of this body state is automatic, largely preset by our genes to respond not to a particular thing but to certain categories of things.
For instance, when we generate states of fear or anger or disgust or happiness, we produce withdrawal behaviors or approach behaviors that have been preserved through evolution because they have proved advantageous to survival. We have inherited this system for sorting out what is good and what is bad, automatically, in order to preserve ourselves.
The power of such nonconscious processing is enormous. Many studies have shown that in normal individuals, the amygdala--a brain structure intimately involved in the fear response and in recognizing fear--will be activated even when a person is not consciously aware of having been presented with a fearful stimulus. The brain can pick up a signal that is well masked at the conscious level. Conversely, individuals with damage to the amygdala may lose the ability to detect negative stimuli, with unfortunate results in their lives.
Similarly, patients with damage to certain regions of the frontal lobe also suffer from an inability to appreciate negative outcomes. Despite maintaining normal intelligence and knowledge, they no longer can run their lives effectively. They cannot learn from their mistakes or think about future consequences. Though they can reason logically, their decision-making ability is flawed. They have lost emotional reactivity at a high level; they can no longer sense, for instance, embarrassment or guilt or pride or shame. They have lost their ability to feel emotion relative to the future consequences of their actions and thus are no longer able to qualify their choices as "potentially good" or "potentially bad."
What we have learned, then, is that the brain has at least two systems for assessing the value of events. One system leads to a conscious recall, through memory, of options for action and of representations of future outcomes. Then we use logical reasoning and knowledge to decide that we will do X instead of Y. Another system, probably evolutionarily far older, acts even before the first one. It activates biases related to our previous emotional experience in comparable situations. These nonconscious biases affect the options and reasoning strategies that we present to our conscious selves.
We do ourselves a disservice when we think of human beings as exclusively logic- or knowledge-driven, and fail to pay attention to the role of the emotions. The two systems are enmeshed because that is the way our brain and our organism have been put together by evolution.
If you have questions or comments on the LC/NIMH Decade of the Brain Project, please contact: [email protected].
Library of Congress Library of Congress Help Desk (01/03/2000)