Ultrastructure and synaptic associations of auditory thalamo-amygdala projections in the rat

J. E. LeDoux, C. R. Farb, T. A. Milner

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Projections from the acoustic thalamus to the lateral nucleus of the amygdala (AL) have been implicated in the formation of emotional memories. In order to begin elucidating the cellular basis of emotional learning in this pathway, the ultrastructure and synaptic associations of acoustic thalamus efferents terminating in AL were studied using wheat-germ agglutinated horse-radish peroxidase (WGA-HRP) and Phaseolus vulgaris Leucoagglutinin (Pha-L) as ultrastructural anterograde axonal markers. The tracers were injected into those areas of the thalamus (medial division of the medial geniculate body and posterior intralaminar nucleus, MGM/PIN) known both to project to AL and to receive afferents from the inferior colliculus. Terminals labeled with WGA-HRP or Pha-L in AL contained mitochrondria and many small, round clear vesicles and 0-3 large, dense-core vesicles. Most labeled terminals formed asymmetric synapses on unlabeled dendrites; of these the majority were on dendritic spines. These data demonstrate that projections from the acoustic thalamus form synapses in AL and provide the first characterization of the ultrastructure and synaptic associations of sensory afferent projections to the amygdala.

Original languageEnglish (US)
Pages (from-to)577-586
Number of pages10
JournalExperimental Brain Research
Issue number3
StatePublished - Jul 1991


  • Acoustic thalamus
  • Amygdala
  • Emotional memories
  • Rat

ASJC Scopus subject areas

  • General Neuroscience


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