Intrinsic connections of the rat amygdaloid complex: Projections originating in the basal nucleus

V. Savander, C. G. Go, Joseph Ledoux, A. Pitkanen

Research output: Contribution to journalArticle

Abstract

The amygdaloid complex is involved in associational processes, such as the formation of emotional memories about sensory stimuli. However, the anatomical connections through which the different amygdaloid nuclei process incoming information and communicate with the other amygdaloid nuclei, is poorly understood. As part of an ongoing project aimed at elucidating the intrinsic connections of the rat amygdaloid complex, we injected the anterograde tracer PHA-L (Phaseolus vulgaris-leucoagglutinin) into different rostrocaudal levels of the basal nucleus of the amygdala in 21 rats and analyzed the distribution of labeled fibers and terminals throughout the amygdaloid complex. The connectional analysis, together with cytoarchitectonic observations, suggested that contrary to previous notions the basal nucleus in the rat has three divisions: magnocellular, intermediate, and parvicellular. The magnocellular division has heavy reciprocal connections with the lateral portion of the parvicellular division and the intermediate division projects weakly to the parvicellular division, whereas the projection from the medial portion of the parvicellular division to the intermediate division is heavy and the lateral and medial portions of the parvicellular division are only weakly interconnected, as are the magnocellular and intermediate divisions. The main intra-amygdaloid targets of the basal nucleus projections are the nucleus of the lateral olfactory tract, the anterior amygdaloid area, the medial and capsular divisions of the central nucleus, the anterior cortical nucleus, and the amygdalohippocampal area. Our findings provide the most detailed understanding of the intra- amygdala connections of the basal nucleus to date and show that the connections within the basal nucleus and between the basal nucleus and other amygdaloid areas are more widespread and topographically organized than previously recognized.

Original languageEnglish (US)
Pages (from-to)345-368
Number of pages24
JournalJournal of Comparative Neurology
Volume361
Issue number2
DOIs
StatePublished - 1995

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Basal Ganglia
Amygdala
Basolateral Nuclear Complex
Corticomedial Nuclear Complex

Keywords

  • amygdala
  • anatomy
  • anterograde tracer
  • memory
  • temporal lobe

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Intrinsic connections of the rat amygdaloid complex : Projections originating in the basal nucleus. / Savander, V.; Go, C. G.; Ledoux, Joseph; Pitkanen, A.

In: Journal of Comparative Neurology, Vol. 361, No. 2, 1995, p. 345-368.

Research output: Contribution to journalArticle

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