Reiner A
Department of Anatomy and Neurobiology, University of Tennessee-Memphis 38163.
Comp Biochem Physiol Comp Physiol. 1993 Apr;104(4):735-48. doi: 10.1016/0300-9629(93)90149-x.
Telencephalic cortex in turtles is a simple three layered-structure. The dorsal most part of this structure is thought to resemble the reptilian forerunner of at least parts of mammalian isocortex. This dorsal part of turtle cortex contains several functionally distinct regions that show similarity in their connections and function to specific areas in mammalian isocortex. The types of neurons found in turtle dorsal cortex (as defined by their morphology and neurotransmitter content) also show great similarity to those observed in mammals, with the major exception that turtle cortex appears to lack the types of neurons found in granular and supragranular layers of mammalian isocortex. Similar results have also been observed in other living reptiles. Thus, one major step in the evolution of reptilian cortex into mammalian cortex must have been the addition of the types of neurons found in the granular and supragranular layers of mammalian isocortex. These observations for turtles also suggest that turtle cortex in particular and reptilian telencephalic cortex in general must differ functionally from mammalian isocortex with respect to those features associated with the laminar and columnar organization of isocortex. These issues are discussed in more detail below and in Reiner (1991).
龟类的端脑皮层是一种简单的三层结构。该结构的最背侧部分被认为类似于至少部分哺乳动物新皮层的爬行动物前身。龟类皮层的这一背侧部分包含几个功能上不同的区域，这些区域在其连接和功能上与哺乳动物新皮层的特定区域表现出相似性。在龟类背侧皮层中发现的神经元类型（根据其形态和神经递质含量定义）也与在哺乳动物中观察到的神经元类型非常相似，主要的例外是龟类皮层似乎缺乏在哺乳动物新皮层颗粒层和颗粒上层中发现的神经元类型。在其他现存爬行动物中也观察到了类似的结果。因此，爬行动物皮层向哺乳动物皮层进化的一个主要步骤一定是增加了在哺乳动物新皮层颗粒层和颗粒上层中发现的神经元类型。对龟类的这些观察结果还表明，特别是龟类皮层以及一般的爬行动物端脑皮层，在与新皮层分层和柱状组织相关的那些特征方面，其功能必定与哺乳动物新皮层不同。这些问题将在下面以及赖纳（1991年）的著作中进行更详细的讨论。
