Cerebral Cortex Advance Access published online on September 23, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp158
Comparative Cytoarchitectural Analyses of Striate and Extrastriate Areas in Hominoids
1 Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, Washington, DC 20052, USA, 2 C. and O. Vogt Institute of Brain Research, Heinrich Heine University, Düsseldorf, D-40225 Düsseldorf, Germany, 3 Institute of Neuroscience and Medicine, INM-1, INM-2, Research Center Jülich, D-52525 Jülich, Germany, 4 Department of Psychiatry and Psychotherapy, Rheinisch-Westfälische Technische Hochschule, RWTH Aachen University, D-52074 Aachen, Germany, 5 Anthropology Department, Langara College, Vancouver, BC V5Y 2Z6, Canada, 6 Department of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA
Address correspondence to Alexandra A. de Sousa, PhD, AHRC Centre for the Evolution of Cultural Diversity, Institute of Archaeology, University College London, 31--34 Gordon Square, London, WC1H 0PY, UK. Email: a.sousa{at}ucl.ac.uk.
The visual cortex is the largest sensory modality representation in the neocortex of humans and closely related species, and its size and organization has a central role in discussions of brain evolution. Yet little is known about the organization of visual brain structures in the species closest to humans—the apes—thus, making it difficult to evaluate hypotheses about recent evolutionary changes. The primate visual cortex is comprised of numerous cytoarchitectonically distinct areas, each of which has a specific role in the processing of visual stimuli. We examined the histological organization of striate (V1) and 2 extrastriate (V2 and ventral posterior) cortical areas in humans, 5 ape species, and a macaque. The cytoarchitectural patterns of visual areas were compared across species using quantitative descriptions of cell volume densities and laminar patterns. We also investigated potential scaling relationships between cell volume density and several brain, body, and visual system variables. The results suggest that interspecific variability in the cytoarchitectural organization of visual system structures can arise independently of global brain and body size scaling relationships. In particular, species-specific differences in cell volume density seem to be most closely linked to the size of structures in the visual system.
Key Words: allometry • evolution • gray level index • hominoids • visual cortex