Neuronal populations in the basolateral nuclei of the amygdala are differentially increased in humans compared with apes: A stereological study

Nicole Barger, Lisa Stefanacci, Cynthia Schumann, Chet C. Sherwood, Jacopo Annese, John M. Allman, Joseph A. Buckwalter, Patrick R. Hof, Katerina Semendeferi

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

In human and nonhuman primates, the amygdala is known to play critical roles in emotional and social behavior. Anatomically, individual amygdaloid nuclei are connected with many neural systems that are either differentially expanded or conserved over the course of primate evolution. To address amygdala evolution in humans and our closest living relatives, the apes, we used design-based stereological methods to obtain neuron counts for the amygdala and each of four major amygdaloid nuclei (the lateral, basal, accessory basal, and central nuclei) in humans, all great ape species, lesser apes, and one monkey species. Our goal was to determine whether there were significant differences in the number or percent of neurons distributed to individual nuclei among species. Additionally, regression analyses were performed on independent contrast data to determine whether any individual species deviated from allometric trends. There were two major findings. In humans, the lateral nucleus contained the highest number of neurons in the amygdala, whereas in apes the basal nucleus contained the highest number of neurons. Additionally, the human lateral nucleus contained 59% more neurons than predicted by allometric regressions on nonhuman primate data. Based on the largest sample ever analyzed in a comparative study of the hominoid amygdala, our findings suggest that an emphasis on the lateral nucleus is the main characteristic of amygdala specialization over the course of human evolution.

Original languageEnglish (US)
Pages (from-to)3035-3054
Number of pages20
JournalJournal of Comparative Neurology
Volume520
Issue number13
DOIs
StatePublished - Sep 1 2012

Keywords

  • Amygdala
  • Ape
  • Comparative neuroanatomy
  • Human evolution
  • Lateral nucleus
  • Stereology

ASJC Scopus subject areas

  • Neuroscience(all)

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    Barger, N., Stefanacci, L., Schumann, C., Sherwood, C. C., Annese, J., Allman, J. M., Buckwalter, J. A., Hof, P. R., & Semendeferi, K. (2012). Neuronal populations in the basolateral nuclei of the amygdala are differentially increased in humans compared with apes: A stereological study. Journal of Comparative Neurology, 520(13), 3035-3054. https://doi.org/10.1002/cne.23118