Chimpanzees’ personality traits are linked to the anatomy of specific brain structures, according to researchers at Georgia State University, The University of Texas MD Anderson Cancer Center and University of Copenhagen.

The findings, published online in the journal NeuroImage in August, reveal that both gray- matter volumes of various frontal cortex regions and gray-matter volume asymmetries (larger right versus left or vice versa) are associated with various personality traits. The results suggest the frontal cortex and asymmetries in this region of the brain play an important role in the neurobiological foundation of broad personality traits.

“Our results confirm the importance of neuroscientific approaches to the study of basic personalities and suggest that when compared to humans many of these associations are comparable in chimpanzees,” said Robert Latzman, assistant professor in the Department of Psychology at Georgia State.

The researchers studied 107 chimpanzees’ brains using magnetic resonance image (MRI) scans and also assessed each chimpanzee’s personality by using a 41-item personality questionnaire. They found chimpanzees who were rated as higher for the personality traits of openness and extraversion had greater gray-matter volumes in the anterior cingulate cortex in both hemispheres of the brain. Chimpanzees who were rated as higher on dominance had larger gray-matter volumes in the left anterior cingulate cortex and right prefrontal cortex. Chimpanzees who rated higher on reactivity/unpredictability had higher gray-matter volumes in the right mesial prefrontal cortex.

All chimpanzees received MRI scans during their annual physical examination. For the personality questionnaire, the chimpanzees were rated by staff members who had worked with the animals for an extended period and felt they had enough experience for an accurate rating. Each item consisted of a single trait with a behavioral definition and a scale ranging from “least descriptive of the chimpanzee” to “most descriptive of the chimpanzee.” The instrument consisted of five dimensions: extraversion, openness, agreeableness, dominance (opposite to the human trait of neuroticism) and reactivity/undependability (a dimension that includes content from the opposite side of the human traits of conscientiousness, agreeableness and extraversion).

Previous studies by this group suggest the existence of largely similar personality traits in humans and chimpanzees, but until this study, researchers had not explored the neuroanatomical basis of these traits in nonhuman primates.

About this neuroscience research

Collaborators for the project include William Hopkins and Lisa Hecht of Georgia State, Hani Freeman of the University of Texas MD Anderson Cancer Center and Steven Schapiro of the University of Texas MD Anderson Cancer Center and University of Copenhagen in Denmark.

Funding: The research was funded by the National Institutes of Health.

Source: LaTina Emerson – Georgia State University

Image Credit: The image is adapted from the Georgia State University press release

Original Research: Abstract for “Neuroanatomical correlates of personality in chimpanzees (Pan troglodytes): Associations between personality and frontal cortex” by Robert D. Latzman, Lisa K. Hecht, Hani D. Freeman, Steven J. Schapiro, and William D. Hopkins in NeuroImage. Published online August 23 2015 doi:10.1016/j.neuroimage.2015.08.041

Abstract

Neuroanatomical correlates of personality in chimpanzees (Pan troglodytes): Associations between personality and frontal cortex

Converging empirical data suggests that a set of largely consistent personality traits exist in both human and nonhuman primates; despite these similarities, almost nothing is known concerning the neurobiological basis of these traits in nonhuman primates. The current study examined associations between chimpanzee personality traits and the grey matter volume and asymmetry of various frontal cortex regions in 107 captive chimpanzees. Chimpanzees rated as higher on Openness and Extraversion had greater bilateral grey matter volumes in the anterior cingulate cortex. Further, chimpanzee rated as higher on Dominance had larger grey volumes in the left anterior cingulate cortex and right Prefrontal Cortex (PFC). Finally, apes rated higher on Reactivity/Unpredictability had higher grey matter volumes in the right mesial PFC. All associations survived after applying False Discovery Rate (FDR) thresholds. Results are discussed in terms of current neuroscientific models of personality which suggest that the frontal cortex, and asymmetries in this region, play an important role in the neurobiological foundation of broad dispositional traits.

“Neuroanatomical correlates of personality in chimpanzees (Pan troglodytes): Associations between personality and frontal cortex” by Robert D. Latzman, Lisa K. Hecht, Hani D. Freeman, Steven J. Schapiro, and William D. Hopkins in NeuroImage. Published online August 23 2015 doi:10.1016/j.neuroimage.2015.08.041

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