Species differences in executive function correlate with hippocampus volume and neocortex ratio across nonhuman...

Area of Science:

• Neuroscience
• Comparative Psychology
• Primatology

Background:

• The relationship between brain size/architecture and cognitive abilities is a long-standing debate in behavioral research.
• Previous studies show correlations between brain size and ecological/behavioral tasks, but empirical backing for a causal link is limited.

Purpose of the Study:

• To investigate the relationship between brain size, brain architecture, and executive function performance across primate species.
• To identify specific brain regions that predict cognitive performance.

Main Methods:

• Assessed cognitive performance on eight executive function tasks in 46 species from 17 primate genera.
• Utilized a model selection approach to analyze correlations between cognitive performance and various brain measures (total brain size, component volumes, absolute vs. relative sizes).

Main Results:

• Cognitive task performance correlated across tasks and with brain size and architecture across species.
• Hippocampus size was the strongest predictor of overall executive function performance.
• The best predictive model included total brain size and relative neocortex size; absolute brain measures were more predictive than relative ones.

Conclusions:

• Findings support the role of the hippocampus in learning and the neocortex in problem-solving and consolidation.
• Clarifies the relationship between overall brain size and specific regional volumes in predicting cognitive function.
• Suggests that traditional encephalization indices may obscure rather than reveal meaningful relationships.