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After studying this chapter, the student should be able to:

  • Know how emotion is defined and manipulated for study.

  • Understand the usefulness of emotion in guiding behavior.

  • Know more about the limbic system and other brain areas important for generating emotion.

  • Recount recent evidence about the crucial role of the amygdala in emotional processing and learning.

  • Understand the role of the ventromedial prefrontal cortex in high-level emotional intelligence.

  • Understand the physiologic changes associated with emotional states and the role of the autonomic nervous system.

  • Understand the brain mechanisms thought to underlie some emotional disorders such as sociopathy and autism.


Emotions are the feelings generated by basic instincts and drives and by the assessment of progress or frustration of those drives. Emotions depend on the limbic system. The limbic system, in turn, interacts with the autonomic nervous system to control whether the body should be in the sympathetic fight/flight body state or oriented toward homeostasis. The limbic system also interacts with sensory organs that assess the state of the environment and with the neocortex, which modulates behavior based on contextual memories. A particularly important part of the brain related to emotion and limbic function is the amygdala–ventromedial frontal lobe system that is responsible for assessing emotionally salient risks, such as those associated with living in social groups.


Basic instincts and drives make their presence felt by generating emotions that motivate the organism toward some action. Emotional drive is both generated by and produced from the state of the autonomic nervous system. Emotional drives are typically based on immediate survival needs such as thirst, hunger, reproductive activity, and social rank maintenance. Note that some of these are internally generated, such as thirst and hunger, whereas others are externally triggered, such as the appearance, sound, or smell of a potential mate or predator. External emotion-generating inputs are transmitted from cephalic sensory organs. The behaviors triggered by external sensory input often depend on learned associations from previous experience.

Emotions can be described as existing along dimensions such as approach/withdrawal and intensity. Fear and disgust are emotions that are associated with withdrawal behavior, whereas happiness promotes approach. Each type of emotion has an associated intensity that is also experienced. Emotions are associated with body states mediated by different relative levels of sympathetic versus parasympathetic neurotransmitters as well as other neurotransmitters and neuromodulators. According to the James-Lange theory of emotion, emotional responses are processed initially at limbic brain levels and the autonomic nervous system, with cognitive responses occurring later along a slower pathway involving higher brain areas. By this theory, the initial emotional reaction to sensory input should be similar in humans to that of primates and other mammals because we share similar, phylogenetically older limbic brain structures. The cognitive human overlay would be unique because of unique human consciousness and language. It is also clearly the ...

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