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2000 Emotion and the Brain
Chapter 74
2000 Emotion and the Brain THE CONCEPT Emotion is not a function of the primitive brain, sometimes called the limbic system, and can be studied as discrete functions, such as fear, that are assignable to specific anatomical regions of the brain.
THE EXPLANATION LeDoux’s 2000 paper on emotion and the brain is a turning point in understanding animal behavior because he clearly expresses a modern view of the neuroscience of emotions. Many concepts of brain function were developed essentially as metaphors (see Chapter 67: 1992 Working Memory) for poorly understood neural systems. This included emotions, which had been considered by scientists at least as far back as Darwin. Emotions are difficult to define. If they are only considered as subjective experiences they remain the realm of theory and metaphor rather than objective investigation. LeDoux (2000) focused primarily on fear and the role of the amygdala in regulating fearful responses and organizing memories associated with fear or with trauma that induces fear. LeDoux (2000) also provides an excellent argument for abandoning the concept of the limbic system. The limbic system is the aggregate of the evolutionarily older parts of the brain including the hypothalamus, amygdala, hippocampus, and the olfactory bulbs. Because mammals have the evolutionarily more recent neocortex laid over the limbic system, some influential psychologists believed that primitive noncognitive behavior—impulse and emotion—was based in the limbic system and that mammals had exclusive possession of cognitive abilities residing in the neocortex. This point of attention relates in interesting ways to Lima and Dill’s (1990, see Chapter 63: 1990 Fear) exploration of the evolutionary ecology of fear a decade earlier. It also plays forward to the more recent concept of behavioral syndromes, for which behavior along a shy bold continuum has been a central research focus (see Chapter 77: 2004 Behavioral Syndromes—Personality in Animals). Worth considering is the idea that fear is somewhat unique Conceptual Breakthroughs in Ethology and Animal Behavior. DOI: http://dx.doi.org/10.1016/B978-0-12-809265-1.00074-5 © 2017 Elsevier Inc. All rights reserved.
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among emotions as its evolutionary value is clear, its ecological consequences are well understood, and we have good knowledge of its neural underpinnings. Can other emotions, for which characterizations are still more subjective, be resolved in the same way? Love, for example, is an extremely subjective concept and it is hard to know whether the bond a companion animal such as a dog or cat feels with its human is love or exploitation. Nevertheless, social bonding—mate with mate, parent with offspring, offspring with sibs, and so on—is common in the animal world and in vertebrates the roles of vasopressin, oxytocin, and dopamine in bonding are well established. So perhaps love will always remain subjective but bonding can be understood in concrete terms. And it might be so for any emotion that can be semantically disentangled from subjectivity. Even contemporary scientists sometimes refer to ‘higher functions’ in the neocortex, despite the fact that we now know that a very broad range of animals have abilities for cognition, calculation, and manipulation even though some lack a neocortex. Current knowledge supports the conclusion that at least some aspects of mental higher functions, including emotion, are present in diverse animal taxa outside the birds and mammals.
IMPACT: 8 LeDoux’s (2000) paper is widely cited because it combines well-argued theory about emotions, the limbic system, and cognition with detailed experimental findings concerning fear. It represents a turning point at which a neurobiological approach to a problem in animal behavior came into congruence with thought about the evolution and ecology of behavior.
SEE ALSO Chapter 27, 1964 Dopamine and Reward Reinforcement; Chapter 37, 1973 Episodic Memory; Chapter 52, 1978 Theory of Mind; Chapter 63; 1990 Fear; Chapter 51, 1978 Animal Models for Depression; Chapter 61, 1985 An Animal Model for Anxiety; Chapter 65, 1991 Pain in Animals.
REFERENCES AND SUGGESTED READING Brown, J.S., Laundre, J.W., Garung, M., 1999. The ecology of fear: optimal foraging, game theory, and trophic interactions. J. Mammal. 80, 385 399. Cardinal, R.N., Parkinson, J.A., Hall, J., Everitt, B.J., 2002. Emotion and motivation: the role of the amygdala, ventral striatum, and prefrontal cortex. Neurosci. Biobehav. Rev. 26, 321 352. LeDoux, J.E., 2000. Emotion circuits in the brain. Ann. Rev. Neurosci. 23, 155 184. Lima, S.L., Dill, L.M., 1990. Behavioral decisions made under the risk of predation: a review and prospectus. Canadian J. Zool. 68, 619 640. Phelps, E.A., LeDoux, J.E., 2005. Contributions of the amygdala to emotion processing: from animal models to human behavior. Neuron 48, 175 187. Young, L.J., Zuoxin Wang, Z., 2004. The neurobiology of pair bonding. Nat. Neurosci. 7, 1048 1054.
2000 Emotion and the Brain THE CONCEPT Emotion is not a function of the primitive brain, sometimes called the limbic system, and can be studied as discrete functions, such as fear, that are assignable to specific anatomical regions of the brain.
THE EXPLANATION LeDoux’s 2000 paper on emotion and the brain is a turning point in understanding animal behavior because he clearly expresses a modern view of the neuroscience of emotions. Many concepts of brain function were developed essentially as metaphors (see Chapter 67: 1992 Working Memory) for poorly understood neural systems. This included emotions, which had been considered by scientists at least as far back as Darwin. Emotions are difficult to define. If they are only considered as subjective experiences they remain the realm of theory and metaphor rather than objective investigation. LeDoux (2000) focused primarily on fear and the role of the amygdala in regulating fearful responses and organizing memories associated with fear or with trauma that induces fear. LeDoux (2000) also provides an excellent argument for abandoning the concept of the limbic system. The limbic system is the aggregate of the evolutionarily older parts of the brain including the hypothalamus, amygdala, hippocampus, and the olfactory bulbs. Because mammals have the evolutionarily more recent neocortex laid over the limbic system, some influential psychologists believed that primitive noncognitive behavior—impulse and emotion—was based in the limbic system and that mammals had exclusive possession of cognitive abilities residing in the neocortex. This point of attention relates in interesting ways to Lima and Dill’s (1990, see Chapter 63: 1990 Fear) exploration of the evolutionary ecology of fear a decade earlier. It also plays forward to the more recent concept of behavioral syndromes, for which behavior along a shy bold continuum has been a central research focus (see Chapter 77: 2004 Behavioral Syndromes—Personality in Animals). Worth considering is the idea that fear is somewhat unique Conceptual Breakthroughs in Ethology and Animal Behavior. DOI: http://dx.doi.org/10.1016/B978-0-12-809265-1.00074-5 © 2017 Elsevier Inc. All rights reserved.
225
226
Conceptual Breakthroughs in Ethology and Animal Behavior
among emotions as its evolutionary value is clear, its ecological consequences are well understood, and we have good knowledge of its neural underpinnings. Can other emotions, for which characterizations are still more subjective, be resolved in the same way? Love, for example, is an extremely subjective concept and it is hard to know whether the bond a companion animal such as a dog or cat feels with its human is love or exploitation. Nevertheless, social bonding—mate with mate, parent with offspring, offspring with sibs, and so on—is common in the animal world and in vertebrates the roles of vasopressin, oxytocin, and dopamine in bonding are well established. So perhaps love will always remain subjective but bonding can be understood in concrete terms. And it might be so for any emotion that can be semantically disentangled from subjectivity. Even contemporary scientists sometimes refer to ‘higher functions’ in the neocortex, despite the fact that we now know that a very broad range of animals have abilities for cognition, calculation, and manipulation even though some lack a neocortex. Current knowledge supports the conclusion that at least some aspects of mental higher functions, including emotion, are present in diverse animal taxa outside the birds and mammals.
IMPACT: 8 LeDoux’s (2000) paper is widely cited because it combines well-argued theory about emotions, the limbic system, and cognition with detailed experimental findings concerning fear. It represents a turning point at which a neurobiological approach to a problem in animal behavior came into congruence with thought about the evolution and ecology of behavior.
SEE ALSO Chapter 27, 1964 Dopamine and Reward Reinforcement; Chapter 37, 1973 Episodic Memory; Chapter 52, 1978 Theory of Mind; Chapter 63; 1990 Fear; Chapter 51, 1978 Animal Models for Depression; Chapter 61, 1985 An Animal Model for Anxiety; Chapter 65, 1991 Pain in Animals.
REFERENCES AND SUGGESTED READING Brown, J.S., Laundre, J.W., Garung, M., 1999. The ecology of fear: optimal foraging, game theory, and trophic interactions. J. Mammal. 80, 385 399. Cardinal, R.N., Parkinson, J.A., Hall, J., Everitt, B.J., 2002. Emotion and motivation: the role of the amygdala, ventral striatum, and prefrontal cortex. Neurosci. Biobehav. Rev. 26, 321 352. LeDoux, J.E., 2000. Emotion circuits in the brain. Ann. Rev. Neurosci. 23, 155 184. Lima, S.L., Dill, L.M., 1990. Behavioral decisions made under the risk of predation: a review and prospectus. Canadian J. Zool. 68, 619 640. Phelps, E.A., LeDoux, J.E., 2005. Contributions of the amygdala to emotion processing: from animal models to human behavior. Neuron 48, 175 187. Young, L.J., Zuoxin Wang, Z., 2004. The neurobiology of pair bonding. Nat. Neurosci. 7, 1048 1054.