Laboratory of Quantitative Neuromorphology, Psychology, The Colorado College, 14 E. Cache La Poudre, Colorado Springs, CO 80903, USA.
Brain Struct Funct. 2011 Jan;215(3-4):273-98. doi: 10.1007/s00429-010-0288-3. Epub 2010 Nov 16.
Virtually nothing is known about the morphology of cortical neurons in the elephant. To this end, the current study provides the first documentation of neuronal morphology in frontal and occipital regions of the African elephant (Loxodonta africana). Cortical tissue from the perfusion-fixed brains of two free-ranging African elephants was stained with a modified Golgi technique. Neurons of different types (N=75), with a focus on superficial (i.e., layers II-III) pyramidal neurons, were quantified on a computer-assisted microscopy system using Neurolucida software. Qualitatively, elephant neocortex exhibited large, complex spiny neurons, many of which differed in morphology/orientation from typical primate and rodent pyramidal neurons. Elephant cortex exhibited a V-shaped arrangement of bifurcating apical dendritic bundles. Quantitatively, the dendrites of superficial pyramidal neurons in elephant frontal cortex were more complex than in occipital cortex. In comparison to human supragranular pyramidal neurons, elephant superficial pyramidal neurons exhibited similar overall basilar dendritic length, but the dendritic segments tended to be longer in the elephant with less intricate branching. Finally, elephant aspiny interneurons appeared to be morphologically consistent with other eutherian mammals. The current results thus elaborate on the evolutionary roots of Afrotherian brain organization and highlight unique aspects of neural architecture in elephants.
关于大象皮质神经元的形态学几乎一无所知。为此，本研究首次记录了非洲象（Loxodonta africana）额叶和枕叶皮质区域的神经元形态。使用改良的高尔基技术对来自两只自由放养的非洲象灌注固定脑的皮质组织进行染色。使用 Neurolucida 软件，在计算机辅助显微镜系统上对不同类型的神经元（N=75）进行了定量分析，重点是浅层（即 II-III 层）的锥体细胞。从定性上看，大象新皮质具有大而复杂的多棘突神经元，其中许多神经元的形态/方向与典型的灵长类和啮齿类锥体细胞不同。大象皮层表现出分叉的顶树突束呈 V 形排列。从定量上看，象额叶皮质中的浅层锥体细胞的树突比枕叶皮质中的更复杂。与人类颗粒上层锥体细胞相比，大象浅层锥体细胞的基底树突总长度相似，但在大象中，树突段往往更长，分支更简单。最后，大象无棘突中间神经元在形态上似乎与其他真兽类哺乳动物一致。因此，目前的结果详细阐述了非洲兽类大脑组织的进化根源，并强调了大象神经结构的独特方面。
