The amygdala: Contributions to fear and stress

Research output: Contribution to journalArticlepeer-review

Abstract

Recent studies have identified major components of the neural system mediating the classical conditioning of defense or fear responses to sensory stimuli. The pathways involve transmission to the amygdala from sensory processing areas in the thalamus and cortex. Within the amygdala, the lateral nucleus receives the sensory inputs and the central nucleus provides the interface with motor systems controlling specific defense responses. Internal connections between the lateral and central nuclei allow the structures involved in receiving inputs and generating outputs to communicate. This circuitry contributes to stress reactions in two important ways. First, by way of these pathways environmental events that are interpreted as threatening activate the hypothalamic-pituitary-adrenal axis and thereby initiate so-called stress reactions. Second, nuclear regions of the amygdala contain receptors for adrenal steroids. Steroids released from the adrenal gland as a result of amygdala activty can therefore influence the processing of the environment by the amygdala. Although the amygdala is likely to play a major role in stress responses, relatively little work has been done to elucidate the nature of its role. This is an important topic for future research aimed at understanding how the biological cascade that constitutes the stress response fits into a broader network involved in emotional and cognitive information processing functions. In contrast to other models of stress, fear conditioning allows us to approach this complex problem armed with a clear understanding of major aspects of the circuitry involved in processing stress-inducing stimuli.

Original languageEnglish (US)
Pages (from-to)231-237
Number of pages7
JournalSeminars in the Neurosciences
Volume6
Issue number4
DOIs
StatePublished - 1994

Keywords

  • Classical conditioning
  • Defense
  • Emotion
  • Learning
  • Limbic system
  • Memory

ASJC Scopus subject areas

  • Neuroscience(all)

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