Preuss T M, Beck P D, Kaas J H
Department of Psychology, Vanderbilt University, Nashville, Tenn. 37240.
Brain Behav Evol. 1993;42(6):321-35. doi: 10.1159/000114169.
Slow lorises (Nycticebus coucang) are nocturnal prosimian (i.e. strepsirhine) primates, closely related to bushbabies (Galago spp.). We examined the organization of visual cortex in four hemispheres from two slow lorises, using connectional and architectonic techniques. All hemispheres were flattened and sections stained for myelin and cytochrome oxidase (CO). Our results indicate, first, that the primary visual area (V1) in slow lorises has a system of small CO-dense blobs, as has been described in most other anthropoid and prosimian primates examined to date. The second visual area (V2) is characterized by broad, stripe-like zones of dense CO staining separated by zones of lighter staining. Loris V2 stripes are less distinct than those of anthropoid primates, and separate classes of thin and thick dark stripes are not apparent. However, V2 stripes are much better developed than in Galago, where they are virtually absent. Injections of wheat-germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) in area V1 revealed reciprocal connections with area V2, and the middle temporal (MT) and dorsolateral (DL) extrastriate areas. Area MT was also identified by its distinctive, dense myelination. As has been reported in anthropoids, DL can be divided into separate caudal and rostral divisions, which differ in myelin and CO staining, and in the strength of their connections with V1. Taken together, our results suggest that many of the features that characterize visual cortex organization in anthropoid primates are present in prosimians and thus probably evolved early in primate history, prior to the diversification of modern primate groups.
懒猴（蜂猴属）是夜行性原猴亚目（即湿鼻猴）灵长类动物，与丛猴（婴猴属）亲缘关系密切。我们使用连接和架构技术，对两只懒猴的四个脑半球的视觉皮层组织进行了研究。所有脑半球均被展平，切片用髓磷脂和细胞色素氧化酶（CO）染色。我们的研究结果表明，首先，懒猴的初级视觉区（V1）有一个由小的CO密集斑组成的系统，这与迄今为止研究的大多数其他类人猿和原猴亚目灵长类动物中所描述的情况一致。第二视觉区（V2）的特征是有宽的、条纹状的密集CO染色区，被较浅染色的区域隔开。懒猴的V2条纹不如类人猿灵长类动物的明显，且薄暗条纹和厚暗条纹的不同类别不明显。然而，V2条纹比婴猴的发达得多，婴猴的V2条纹几乎不存在。在V1区注射与辣根过氧化物酶结合的小麦胚芽凝集素（WGA-HRP），显示与V2区、颞中（MT）区和背外侧（DL）纹外区有相互连接。MT区也因其独特的密集髓鞘形成而被识别。正如在类人猿中所报道的那样，DL区可分为单独的尾侧和吻侧部分，它们在髓鞘和CO染色以及与V1区连接的强度方面存在差异。综合来看，我们的研究结果表明，类人猿灵长类动物视觉皮层组织的许多特征在原猴亚目灵长类动物中也存在，因此可能早在灵长类动物历史早期，在现代灵长类群体分化之前就已经进化出来了。
