Doctoral Dissertation Research: Evolution of the Hominoid Striate and Extrastriate Visual Cortex

George Washington University, Washington DC

Investigators

Abstract

The size and organization of the cerebral cortex has played a fundamental role in studies of human and primate brain evolution. Yet little information exists about the cerebral cortex in modern humans and closely related ape species. Differences between the modern human cortex and that of the usual primate model, the macaque, have largely been ignored by the neurosciences, and there is a dearth of useful comparative data. This dissertation research project will study functionally distinct, hierarchically organized, cerebral cortical areas involved in the processing of visual information. These cortical areas, which make up the visual cortex, comprise the largest sensory domain of the primate cerebral cortex. Visual areas will be investigated across modern humans, apes and Old World monkeys. The student will use modern microanatomical techniques to identify and describe visual areas according to consistent quantitative and qualitative microanatomical criteria. Detailed cortical maps will be generated for each species investigated. Visual area volumes will be estimated for each specimen. The data obtained during the course of the study will provide a framework for further research on the higher primate visual cortex. Specific questions about brain organization and behavior will also be addressed. For example, the study will test the hypothesis that the human lineage has experienced a unique increase in the proportion of visual cortex that is allocated to higher level processing. Important broader impacts of the new data generated here are 1) information about the visual cortices of apes will be made available for the first time, 2) they will enable human and monkey visual areas to be interpreted within a phylogenetic perspective, and, 3) the data will improve our understanding of how modern human visual areas should be defined. The database created by this project, including images and comparative descriptions of visual areas, will be made available on a website. Researchers from diverse fields will be able to use this information to locate these visual areas in studies of higher primate brains. These data will also make it possible to determine genetic profiles of specific cortical areas, and then compare these profiles across higher primate species. Finally, this project will encourage interdisciplinary science by enabling a physical anthropologist to become trained in neurobiological laboratory techniques.