title: The neocortex of cetartiodactyls. II. Neuronal morphology of the visual and motor cortices in the giraffe (Giraffa camelopardalis).
abstract: The present quantitative study extends our investigation of cetartiodactyls by exploring the neuronal morphology in the giraffe (Giraffa camelopardalis) neocortex. Here, we investigate giraffe primary visual and motor cortices from perfusion-fixed brains of three subadults stained with a modified rapid Golgi technique. Neurons (n = 244) were quantified on a computer-assisted microscopy system. Qualitatively, the giraffe neocortex contained an array of complex spiny neurons that included both "typical" pyramidal neuron morphology and "atypical" spiny neurons in terms of morphology and/or orientation. In general, the neocortex exhibited a vertical columnar organization of apical dendrites. Although there was no significant quantitative difference in dendritic complexity for pyramidal neurons between primary visual (n = 78) and motor cortices (n = 65), there was a significant difference in dendritic spine density (motor cortex > visual cortex). The morphology of aspiny neurons in giraffes appeared to be similar to that of other eutherian mammals. For cross-species comparison of neuron morphology, giraffe pyramidal neurons were compared to those quantified with the same methodology in African elephants and some cetaceans (e.g., bottlenose dolphin, minke whale, humpback whale). Across species, the giraffe (and cetaceans) exhibited less widely bifurcating apical dendrites compared to elephants. Quantitative dendritic measures revealed that the elephant and humpback whale had more extensive dendrites than giraffes, whereas the minke whale and bottlenose dolphin had less extensive dendritic arbors. Spine measures were highest in the giraffe, perhaps due to the high quality, perfusion fixation. The neuronal morphology in giraffe neocortex is thus generally consistent with what is known about other cetartiodactyls.
authors.affiliation: Laboratory of Quantitative Neuromorphology, Psychology, Colorado College, 14 E. Cache La Poudre, Colorado Springs, CO, 80903, USA, bjacobs@coloradocollege.edu.
authors.forename: Bob
authors.initials: B
authors.lastname: Jacobs
authors.forename: Tessa
authors.initials: T
authors.lastname: Harland
authors.forename: Deborah
authors.initials: D
authors.lastname: Kennedy
authors.forename: Matthew
authors.initials: M
authors.lastname: Schall
authors.forename: Bridget
authors.initials: B
authors.lastname: Wicinski
authors.forename: Camilla
authors.initials: C
authors.lastname: Butti
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Hof
authors.forename: Chet C
authors.initials: CC
authors.lastname: Sherwood
authors.forename: Paul R
authors.initials: PR
authors.lastname: Manger
mesh_terms: D000818:Animals; D002591:Cetacea; D003712:Dendrites / Q000473:pathology* / Q000502:physiology; D000068276:Giraffes; D008297:Male; D009044:Motor Cortex / Q000473:pathology*; D019579:Neocortex / Q000473:pathology*; D009474:Neurons / Q000473:pathology*; D014793:Visual Cortex / Q000473:pathology*