The Science Behind Fear and Anxiety

In a packed theater at the Rubin Museum last Wednesday, Joseph LeDoux, Ph.D., and Mark Epstein, M.D., shared the stage to untangle the mysteries behind two emotions that we are all too familiar with: anxiety and fear. Epstein is a psychiatrist in New York City, who blends Buddhist practices with his work in psychotherapy. Ledoux directs the Emotional Brain Institute of New York University, where he is also University Professor.

Epstein (left) and LeDoux (right) Photo by Lyn Hughes, courtesy Rubin Museum of Art

Epstein (left) and LeDoux (right) Photo by Lyn Hughes, courtesy of the Rubin Museum of Art

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Rethinking Emotion in the Lab

As I started reading Dana Alliance member Joseph LeDoux’s perspective article in the latest issue of Neuron, I had one picture of what the purring cat on my lap was feeling. After finishing the article, I had quite another. What if instead of thinking about whether animals have feelings similar to ours we think about what we have that goes beyond the “survival circuits and functions” seen in animals?

LeDoux, who wrote The Emotional Brain in 1998, has studied the topic for decades; he described his new perspective, a synthesis or rethinking of the field, at the annual meeting of the American Association for the Advancement of Science (AAAS). “Feelings are important, but I think they need to be studied in humans,” not animals, he said.

“Both psychotherapy and drug therapy for psychological issues could be improved by understanding emotions,” but the problem is, we don’t agree on how to define emotion itself. We often use the terms for feelings and emotion interchangeably (emotional pain v. measurable physical pain, for example), and “whatever problems might arise from using ‘feeling’ words to study human emotion, they are greatly compounded by using these words in animal research.”

Should we be looking for happiness, sadness, or love in the animal brain? No, he said. Instead, we should look for “conserved survival circuits”: systems the brain uses for defense, to manage energy and nutrition, to balance fluids and body temperature, and to procreate. "You're not going to find a joy or pleasure circuit of the brain,” for example, he said. "Pleasure is not a function of any one of these systems, but an integrated result of them."

Cleo the CatCleo is feeling…sleepy?

In the Neuron paper, 14 pages of clear, thorough text with another almost 8 pages of references, LeDoux sets his thinking out step-by-step. His main examples are of defense and reactions to fear; that has been the focus of his decades of research. Table 1 (page 661) suggests the many roles so-called emotional stimuli could play in circuits: “triggers” that activate them, “incentives” that could modify behavior, and “reinforcers” that support learning and memory. I also found Figure 2 useful, illustrating how a conditioned stimulus could travel a survival circuit to lead to innate behavior and perhaps through more paths to lead to learned, goal-directed actions.

LeDoux writes: “Consciousness and feelings are topics that are best studied in humans. Research on the neural basis of feelings in humans is in its infancy. We will never know what an animal feels. But if we can find neural correlates of conscious feelings in humans (and distinguish them from correlates of unconscious emotional computations in survival circuits), and show that similar correlates exists in homologous brain regions in animals, then some basis for speculating about animal feelings and their nature would exist.”

I can know that Cleo’s purring is a direct result of my petting her, but, I must remind myself, what she is feeling remains a mystery.

— Nicky Penttila

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