title: Neocortical neuron morphology in Afrotheria: comparing the rock hyrax with the African elephant.
abstract: The mammalian neocortex contains a great variety of neuronal types. In particular, recent studies have shown substantial morphological diversity among spiny projecting neurons in species that diverged close to the base of the mammalian radiation (e.g., monotremes, afrotherians, and xenarthrans). Here, we used a Golgi technique to examine different neuronal morphologies in an afrotherian species, the rock hyrax (Procavia capensis), and provide a comparison with the related African elephant (Loxodonta africana). Results showed that spiny neurons in the rock hyrax neocortex exhibit less morphological variation than in elephants, displaying a higher frequency of relatively "typical" pyramidal neurons. A quantitative comparison of rock hyrax pyramidal neuron morphology between frontal and visual areas, moreover, revealed greater spine density of neurons in frontal cortex, but no differences in other morphological aspects. Regional variations in pyramidal structure have also been observed in the African elephant, as well as a number of primate species.
authors.affiliation: Department of Anthropology, The George Washington University, Washington, DC, USA. bianchi.serena80@gmail.com
authors.forename: Serena
authors.initials: S
authors.lastname: Bianchi
authors.forename: Amy L
authors.initials: AL
authors.lastname: Bauernfeind
authors.forename: Kanika
authors.initials: K
authors.lastname: Gupta
authors.forename: Cheryl D
authors.initials: CD
authors.lastname: Stimpson
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Spocter
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Bonar
authors.forename: Paul R
authors.initials: PR
authors.lastname: Manger
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Hof
authors.forename: Bob
authors.initials: B
authors.lastname: Jacobs
authors.forename: Chet C
authors.initials: CC
authors.lastname: Sherwood
mesh_terms: D000717:Anatomy, Comparative; D000818:Animals; D002452:Cell Count; D048430:Cell Shape; D048429:Cell Size; D003712:Dendrites / Q000502:physiology; D004606:Elephants / Q000033:anatomy & histology*; D005260:Female; D007043:Hyraxes / Q000033:anatomy & histology*; D008297:Male; D019579:Neocortex / Q000033:anatomy & histology* / Q000166:cytology* / Q000648:ultrastructure; D009474:Neurons / Q000166:cytology*; D017966:Pyramidal Cells / Q000166:cytology