Broca's area homologue in chimpanzees (Pan troglodytes): probabilistic mapping, asymmetry, and comparison to humans.

Bibliographic Collection: 
MOCA Reference, APE
Publication Type: Journal Article
Authors: Schenker, N. M.; Hopkins, W. D.; Spocter, M. A.; Garrison, A. R.; Stimpson, C. D.; Erwin, J. M.; Hof, P. R.; Sherwood, C. C.
Year of Publication: 2010
Journal: Cereb Cortex
Volume: 20
Issue: 3
Pagination: 730-42
Date Published: 03/2010
Publication Language: eng
ISSN: 1460-2199
Keywords: Animals, Brain Mapping, Cell Count, Female, Frontal Lobe, Functional Laterality, Humans, Magnetic Resonance Imaging, Male, Neurofilament Proteins, Neurons, Pan troglodytes, Probability, Reproducibility of Results, Statistics, Nonparametric, Stereotaxic Techniques

Neural changes that occurred during human evolution to support language are poorly understood. As a basis of comparison to humans, we used design-based stereological methods to estimate volumes, total neuron numbers, and neuron densities in Brodmann's areas 44 and 45 in both cerebral hemispheres of 12 chimpanzees (Pan troglodytes), one of our species' closest living relatives. We found that the degree of interindividual variation in the topographic location and quantitative cytoarchitecture of areas 44 and 45 in chimpanzees was comparable to that seen in humans from previous studies. However, in contrast to the documented asymmetries in humans, we did not find significant population-level hemispheric asymmetry for any measures of areas 44 and 45 in chimpanzees. Furthermore, there was no relationship between asymmetries of stereological data and magnetic resonance imaging-based measures of inferior frontal gyrus morphology or hand preference on 2 different behavioral tasks. These findings suggest that Broca's area in the left hemisphere expanded in relative size during human evolution, possibly as an adaptation for our species' language abilities.

DOI: 10.1093/cercor/bhp138
Alternate Journal: Cereb. Cortex
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