Survival Circuits In Animal Brains: What Can They Tell Us About Human Emotion?

New York University neuroscientist Joseph LeDoux, author of "The Emotional Brain", has come up with a new theory called "the survival circuit concept" that he outlines in Wednesday's issue of the journal Neuron. He suggests that instead of asking whether the feelings and emotions we humans experience are also present in other animals, we should ask to what extent the survival circuits present in other animals are also present in humans, and then consider how they contribute to emotions.

The basis for his reasoning, drawn from twenty years researching emotion and memory in the brain, is the neurological common ground that exists between humans and other animals: we both have brain functions used for survival, these include "circuits" responsible for defense, managing energy and nutrition, fluid balance, regulating heat, and reproduction.

LeDoux, a professor in New York University's Center for Neuroscience and Department of Psychology, says in a press statement released earlier this week that while the functions of these "survival circuits" are not causally related to emotional feelings, they will contribute to them indirectly.

"The survival circuit concept integrates ideas about emotion, motivation, reinforcement, and arousal in the effort to understand how organisms survive and thrive by detecting and responding to challenges and opportunities in daily life," he explains.

LeDoux, who is also director of the Emotional Brain Institute, part of the Nathan S. Kline Institute for Psychiatric Research, is fully aware of the difficulty of researching feelings and emotions. It is not easy, he says, because you can't measure them directly, you have to rely on "outward expression of emotional responses, or on verbal declarations by the person experiencing the feeling, as ways of assessing what that person is feeling".

"This is true both when scientists do research on emotions and when people judge emotions in their social interactions with one another," he adds.

As if that is not complicated enough, we are even more limited when we try to interpret the emotions and feelings of animals.

LeDoux says we tend to ascribe human subjective feelings to explain what we see when animals behave in ways we can relate to:

"When a deer freezes to the sound of a shotgun we say it is afraid, and when a kitten purrs or a dog wags its tail, we say it is happy."

Although LeDoux accepts that we may probably never know what animals truly "feel", he thinks we could improve the way we try to understand and interpret their emotions. One way to do this is to look at the brain, and he suggests:

"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."

LeDoux has done a lot of work on fear, and his research shows we can respond to danger before we even "know" consciously what we are responding to. He has also discovered a lot about how we form and store emotional memories in the brain.

His research has helped us to map the brain's neural circuits for fear and fear memory, to the point of identifying cells, synapses and molecules that make emotional learning and memory possible.