Parcellation and volumetry of the amygdala in four primate species
Description
The amygdala is a cellularly diverse structure located in the temporal lobe of the brain and known to play a key role in emotional response. This subcortical structure is a prime target for ongoing studies of social and emotional complexity due to its role as a signaler for anger, fear, and reward-based learning which shape primate behavior. Of the growing list of socially complex animals, non-human primates (NHPs) are of increasing interest due to their relation to humans as well as the opportunity to gain insight into NHP’s socioemotional lives and the shared neural machinery governing complex behavior. To investigate potential species-specific differences in the relative size of the amygdala in NHPs, we quantitatively compared rostro-caudal histological sections through the amygdala of four primate species (Squirrel monkey, Howler monkey, northern plains langur, mandrill). Using cytoarchitectural criteria, we parcellated the nuclear group of the pallial amygdala into its lateral, basal and antero-basal components and assessed the size of these nuclei relative to whole amygdala and brain size as well as hemispheric asymmetry. Our results revealed a consistent pattern of positive scaling in amygdala subcomponent size related to both amygdala volume and brain volume as well as evidence for anatomical asymmetry in the volume of the amygdaloid sub-nuclei. In conclusion, while preliminary we suspect that further development of this work to include more species will help provide unique insight into the anatomical restructuring of the amygdala to support the arrangement of complex social behavior associated with non-human primates.
Citation Information
Wall, Marlee and Spocter, Muhammad A., "Parcellation and volumetry of the amygdala in four primate species" (2026). Office of Research DMU Research Symposium. 101.
https://digitalcommons.dmu.edu/researchsymposium/2025rs/2025abstracts/101
Parcellation and volumetry of the amygdala in four primate species
The amygdala is a cellularly diverse structure located in the temporal lobe of the brain and known to play a key role in emotional response. This subcortical structure is a prime target for ongoing studies of social and emotional complexity due to its role as a signaler for anger, fear, and reward-based learning which shape primate behavior. Of the growing list of socially complex animals, non-human primates (NHPs) are of increasing interest due to their relation to humans as well as the opportunity to gain insight into NHP’s socioemotional lives and the shared neural machinery governing complex behavior. To investigate potential species-specific differences in the relative size of the amygdala in NHPs, we quantitatively compared rostro-caudal histological sections through the amygdala of four primate species (Squirrel monkey, Howler monkey, northern plains langur, mandrill). Using cytoarchitectural criteria, we parcellated the nuclear group of the pallial amygdala into its lateral, basal and antero-basal components and assessed the size of these nuclei relative to whole amygdala and brain size as well as hemispheric asymmetry. Our results revealed a consistent pattern of positive scaling in amygdala subcomponent size related to both amygdala volume and brain volume as well as evidence for anatomical asymmetry in the volume of the amygdaloid sub-nuclei. In conclusion, while preliminary we suspect that further development of this work to include more species will help provide unique insight into the anatomical restructuring of the amygdala to support the arrangement of complex social behavior associated with non-human primates.
