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Evolution of Specialized Pyramidal Neurons in Primate Visual and Motor Cortex

Sherwood, Chet C. and Lee, Paula W. H. and Rivara, Claire-Benedicte and Holloway, Ralph L. and Gilissen, Emmanuel P. E. and Simmons, Robert M. T. and Hakeem, Atiya and Allman, John M. and Erwin, Joseph M. and Hof, Patrick R. (2003) Evolution of Specialized Pyramidal Neurons in Primate Visual and Motor Cortex. Brain Behavior And Evolution, 61 (1). pp. 28-44. ISSN 1421-9743. doi:10.1159/000068879.

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The neocortex of primates contains several distinct neuron subtypes. Among these, Betz cells of primary motor cortex and Meynert cells of primary visual cortex are of particular interest for their potential role in specialized sensorimotor adaptations of primates. Betz cells are involved in setting muscle tone prior to fine motor output and Meynert cells participate in the processing of visual motion. We measured the soma volumes of Betz cells, Meynert cells, and adjacent infragranular pyramidal neurons in 23 species of primate and two species of non-primate mammal (Tupaia glis and Pteropus poliocephalus) using unbiased stereological techniques to examine their allometric scaling relationships and socioecological correlations. Results show that Betz somata become proportionally larger with increases in body weight, brain weight, and encephalization whereas Meynert somata remain a constant proportion larger than other visual pyramidal cells. Phylogenetic variance in the volumetric scaling of these neuronal subtypes might be related to species-specific adaptations. Enlargement of Meynert cells in terrestrial anthropoids living in open habitats, for example, might serve as an anatomical substrate for predator detection. Modification of the connectional and physiological properties of these neurons could constitute an important evolutionary mode for species-specific adaptation.

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Additional Information:© 2003 S. Karger AG. Received: October 1, 2002. Returned for revision: November 11, 2002. Accepted after revision: November 2002. We thank Drs. E.A. Nimchinsky and P.J. Gannon, and E.C. Kirk, E. Bush, and S.C. McFarlin for helpful discussion, Drs. K. Zilles and H.D. Frahm for help with the Stephan collection, and C. Buitron and V.V. Oruganti for expert technical assistance. Great ape specimens used in this study were on loan to the Comparative Neurobiology of Aging Resource supported by NIH AG14308. This work was supported by the Leakey Foundation, the Wenner-Gren Foundation, NSF BCS0121286, NSF DBI9602234 (to NYCEP), and the Mount Sinai School of Medicine. P.R. Hof is the Regenstreif Professor of Neuroscience.
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Leakey FoundationUNSPECIFIED
Wenner-Gren FoundationUNSPECIFIED
Mount Sinai School of MedicineUNSPECIFIED
Subject Keywords:Mammals; Primates; Brain evolution; Betz cell; Meynert cell; Motor cortex; Visual cortex
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Record Number:CaltechAUTHORS:20170408-141758235
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75919
Deposited By: 1Science Import
Deposited On:19 Apr 2017 22:26
Last Modified:15 Nov 2021 16:56

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