Comparative analysis of the dendritic organization of principal neurons in the lateral and central nuclei of the rhesus macaque and rat amygdala

ABSTRACT The amygdala plays a critical role in emotional processing and has been implicated in the etiology of numerous psychiatric disorders. It is an evolutionarily ancient structure that is enlarged in primates relative to rodents. Certain amygdala nuclei, such as the lateral nucleus, show relati...

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Veröffentlicht in:Journal of comparative neurology (1911) 2014-02, Vol.522 (3), p.689-716
Hauptverfasser: Morgan, John T., Amaral, David G.
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Sprache:eng
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Zusammenfassung:ABSTRACT The amygdala plays a critical role in emotional processing and has been implicated in the etiology of numerous psychiatric disorders. It is an evolutionarily ancient structure that is enlarged in primates relative to rodents. Certain amygdala nuclei, such as the lateral nucleus, show relatively greater phylogenetic expansion than other nuclei. However, it is unknown whether there is also differential alteration in neuronal features. To address this question, we examined the dendritic arbors of principal neurons, visualized by using the Golgi method, in the lateral and central nuclei of young adult rhesus macaques and rats. Total dendritic length is greater in the macaque than in the rat. Dendritic trees are increased by 250% in length in the lateral nucleus of the monkey compared with the rat (6,009 μm vs. 2,473 μm); dendritic tree length in the central nucleus is increased by 50% (1,786 μm vs. 1,232 μm). Somal volume is increased 62% between species in the lateral nucleus and 48% in the central nucleus. Spine density is lower on macaque lateral nucleus dendrites compared with rat (−22%) but equivalent in the central nucleus. Spines are equally long in the lateral nucleus of rat and macaque, but spines are longer by about 20% in the central nucleus of the macaque. The alterations in dendritic structure that we observed between the two species suggest differences in the number and spacing of inputs into these nuclei that undoubtedly influence amygdala function. J. Comp. Neurol. 522:689–716, 2014. © 2013 Wiley Periodicals, Inc. Are there differences between mammalian species in dendritic arbor size and structure? If so, are those differences consistent across brain regions? We examined dendritic arbor features in the lateral nucleus and medial division of the central nucleus of the amygdala in rhesus macaque and rat. Dendritic arbors were enlarged in the macaque, with greater expansion in the lateral nucleus, which receives inputs primarily from many neocortical regions that have expanded greatly in the primate brain relative to the rodent brain.
ISSN:0021-9967
1096-9861
DOI:10.1002/cne.23467