Article

Projections from the lateral, basal, and accessory basal nuclei of the amygdala to the hippocampal formation in rat.

A.I. Virtanen Institute, University of Kuopio, Finland.
The Journal of Comparative Neurology (impact factor: 3.81). 02/1999; 403(2):229-60. pp.229-60
Source: PubMed

ABSTRACT The amygdaloid complex and hippocampal formation mediate functions involving emotion and memory. To investigate the connections that regulate the interactions between these regions, we injected the anterograde tracer Phaseolus vulgaris-leucoagglutinin into various divisions of the lateral, basal, and accessory basal nuclei of the rat amygdala. The heaviest projection to the entorhinal cortex originates in the medial division of the lateral nucleus which innervates layer III of the ventral intermediate and dorsal intermediate subfields. In the basal nucleus, the heaviest projection arises in the parvicellular division and terminates in layer III of the amygdalo-entorhinal transitional subfield. In the accessory basal nucleus, the parvicellular division heavily innervates layer V of the ventral intermediate subfield. The most substantial projection to the hippocampus originates in the basal nucleus. The caudomedial portion of the parvicellular division projects heavily to the stratum oriens and stratum radiatum of CA3 and CA1. The accessory basal nucleus projects to the stratum lacunosum-moleculare of CA1. The subiculum receives a substantial input from the caudomedial parvicellular division. The parasubiculum receives dense projections from the caudal portion of the medial division of the lateral nucleus, the caudomedial parvicellular division of the basal nucleus, and the parvicellular division of the accessory basal nucleus. Our data show that select nuclear divisions of the amygdala project to the entorhinal cortex, hippocampus, subiculum, and parasubiculum in segregated rather than overlapping terminal fields. These data suggest that the amygdaloid complex is in a position to modulate different stages of information processing within the hippocampal formation.

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Keywords

accessory basal nucleus
 
accessory basal nucleus projects
 
amygdalo-entorhinal transitional subfield
 
amygdaloid complex
 
anterograde tracer Phaseolus vulgaris-leucoagglutinin
 
caudal portion
 
caudomedial parvicellular division
 
caudomedial portion
 
dorsal intermediate subfields
 
heaviest projection
 
innervates layer III
 
layer III
 
medial division
 
parvicellular division
 
parvicellular division projects
 
select nuclear divisions
 
stratum lacunosum-moleculare
 
substantial projection
 
various divisions
 
ventral intermediate subfield