Variable temporoinsular cortex neuroanatomy in primates suggests a bottleneck effect in eastern gorillas |
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| Authors: | Sarah K. Barks Amy L. Bauernfeind Christopher J. Bonar Michael R. Cranfield Alexandra A. de Sousa Joseph M. Erwin William D. Hopkins Albert H. Lewandowski Antoine Mudakikwa Kimberley A. Phillips Mary Ann Raghanti Cheryl D. Stimpson Patrick R. Hof Karl Zilles Chet C. Sherwood |
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| Affiliation: | 1. Center for the Advanced Study of Hominid Paleobiology and Department of Anthropology, The George Washington University, Washington, DC;2. Dallas Zoo, Dallas, Texas;3. Mountain Gorilla Veterinary Project, School of Veterinary Medicine, University of California Davis, Davis, California;4. Department of Life Sciences, University of Coimbra, Coimbra, Portugal;5. Neuroscience Institute, Georgia State University, Atlanta, Georgia;6. Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center, Atlanta, Georgia;7. Cleveland Metroparks Zoo, Cleveland, Ohio;8. Rwanda Development Board, Department of Tourism and Conservation, Kigale, Rwanda;9. Department of Psychology, Trinity University, San Antonio, Texas;10. Department of Anthropology and School of Biomedical Sciences, Kent State University, Kent, Ohio;11. Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York;12. New York Consortium in Evolutionary Primatology, New York, New York;13. Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany;14. C.&O. Vogt Institute of Brain Research, Heinrich‐Heine University Düsseldorf, Düsseldorf, Germany;15. Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University, Aachen, Germany |
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| Abstract: | We describe an atypical neuroanatomical feature present in several primate species that involves a fusion between the temporal lobe (often including Heschl's gyrus in great apes) and the posterior dorsal insula, such that a portion of insular cortex forms an isolated pocket medial to the Sylvian fissure. We assessed the frequency of this fusion in 56 primate species (including apes, Old World monkeys, New World monkeys, and strepsirrhines) by using either magnetic resonance images or histological sections. A fusion between temporal cortex and posterior insula was present in 22 species (seven apes, two Old World monkeys, four New World monkeys, and nine strepsirrhines). The temporoinsular fusion was observed in most eastern gorilla (Gorilla beringei beringei and G. b. graueri) specimens (62% and 100% of cases, respectively) but was seen less frequently in other great apes and was never found in humans. We further explored the histology of this fusion in eastern gorillas by examining the cyto‐ and myeloarchitecture within this region and observed that the degree to which deep cortical layers and white matter are incorporated into the fusion varies among individuals within a species. We suggest that fusion between temporal and insular cortex is an example of a relatively rare neuroanatomical feature that has become more common in eastern gorillas, possibly as the result of a population bottleneck effect. Characterizing the phylogenetic distribution of this morphology highlights a derived feature of these great apes. J. Comp. Neurol. 522:844–860, 2014. © 2013 Wiley Periodicals, Inc. |
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| Keywords: | cerebral cortex cortical fusion auditory cortex ape |
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