Closing Session"The Future of the Study of Emotion"
Joseph LeDoux, Ph.D., the Henry and Lucy Moses Professor of Science at New York University's Center for Neural Science, is the author of The Emotional Brain.
Emotions define who we are to ourselves as well as to others. They are at the core of many psychiatric disorders, and they can also alter our physical well-being.
As we contemplate the study of emotion, we need to make several distinctions.
Consciousness and cognition. Cognition is our ability to process and store information about the world. We are not necessarily conscious of those activities as they occur.
Emotion and cognition. We also must distinguish between cognition and emotion, recognizing that many aspects of emotion rely on cognition and cognition similarly depends on emotion.
Implicit and explicit memory. Our ability to consciously remember something is not necessarily the same as our ability to respond to something on the basis of past learning. The emotional system of the brain is one of the most powerful learning systems that we have, but it is an implicit learning system. It can contribute to explicit memory, so that we have memories about emotional situations that are explicit and consciously available. But the many systems involved in implicit learning are what give rise to physiological and other responses in the presence of stimuli associated with past pleasure or danger.
Nature and nurture. We come into the world capable of being afraid and capable of being happy, but we must learn which things make us afraid and which make us happy.
Fear is the emotion most responsible for reinvigorating the study of emotion. Our studies have led us to understand that the amygdala is the key, no matter how the stimulus comes into the brain: through the eyes, the nose, the ears.
The amygdala is programmed to react without benefit of input from the thinking part of the brain, the cortex. Eventually the cortex gets involved, but this processing takes longer.
We also know that the amygdala's input to the cortex is much stronger than communication the other way. An emotional reaction like fear can more easily gain control over the cortex and influence cortical processes than the cortex can gain control over the amygdala. This may explain why psychotherapy is such a difficult process.
Thus, it is possible for emotions to be triggered in us without the cortex knowing exactly what is going on. For many of us, this happens all the time. In some people, this may be especially strong, so their emotions are being triggered in ways that prevent them from having insight into what they are doing.
Given the social and personal cost of mental illness, and especially anxiety and mood disorders, we need to understand much more about the pharmacology and biochemistry and molecular biology of these systems. We need to be able to target drugs to the specific brain systems involved in a particular disorder, but we need to know which parts those are.
There are some pitfalls we must avoid as we begin to study emotion in new and different ways. First, there is a strong tendency now to talk about the amygdala as the key to everything about emotion. I think that is not the case, but if it is the case, we should discover it through research rather than simply assume it. Most of what we know about the amygdala and emotion comes from fear research. While some research has been done on the amygdala's role in positive affect, we will not understand its role until we map the networks involved.
Second, we need to recognize the complexity of emotion and keep in mind the underlying processes. We made progress because we took a very simple task and mapped that out in the brain. If we generalize too much on the basis of that set of data, we are going to be back in the trap of trying to explain too much.
Finally, we need to recognize the diversity of emotions. We should assume that there are multiple emotion systems in the brain: that joy, for example, is not mediated by the fear system, unless and until we have evidence that proves otherwise.
My wish list for the future of emotion research would include four items.
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