In order to determine which changes in the cortical origins of the corticospinal tract (CST) have taken place along the Anthropoid ancestral lineage, the retrograde tracer, horseradish peroxidase was applied to the hemisected spinal cord of 22 carefully selected mammals. Several morphological features of the cells originating the CST were examined in each animal including the number of cells, their distribution across the cortex, their laminar distribution, area, density, concentration and cell type. / The results indicate that two spatially distinct Regions in the neocortex originate corticospinal axons in each of the animals in the sample. In addition to these two Regions probably common to all Therian mammals, the results indicate that a new source of corticospinal axons probably emerged in the Primate Order. This new CST area is located on the lateral surface of the cortex of Prosimians and New World Anthropoids and is buried in the caudal bank of the inferior arcuate sulcus in Old World Anthropoids. / Several strictly quantitative changes in the corticospinal neurons are also described. These quantitative changes can be subdivided into those that occurred in a pre-Prosimian stage (e.g., increase in number, density and column height) and those that occurred in a post-Prosimian stage (e.g., decrease in density, increase in area of origin of the CST). / Finally, these changes, both qualitative and quantitative are discussed with respect to their correspondence with cytoarchitectonically defined and electrophysiologically defined cortical fields. / Source: Dissertation Abstracts International, Volume: 46-10, Section: B, page: 3631. / Thesis (Ph.D.)--The Florida State University, 1985.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75685 |
| Contributors | NUDO, RANDOLPH JOSEPH., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 315 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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