Matelli M, Camarda R, Glickstein M, Rizzolatti G
J Comp Neurol. 1986 Sep 15;251(3):281-98. doi: 10.1002/cne.902510302.
The rostral part of the agranular frontal cortex (area 6) can be subdivided on the basis of its cytoarchitecture, enzymatic properties, and connections into two large sectors: a superior region, lying medial to the spur of the arcuate sulcus, and an inferior region, lying lateral to it. In this study we traced the afferent and efferent connections of the inferior region of area 6 by injecting small amounts of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) and fluorescent tracers (fast blue and diamidino yellow) into restricted parts of inferior area 6 and in physiologically determined fields of area 4. There is an ordered topographic pattern of connections between inferior area 6 and area 4. The region near the spur of the arcuate sulcus (hand field) projects to the area 4 hand field while the lateral part of inferior area 6 (mouth field) is connected with the corresponding field in area 4. The organization of the connections between the two fields is, however, different. The hand fields in area 6 and 4 have direct reciprocal projections, whereas the mouth field in the postarcuate cortex relays information to area 4 via a zone intermediate between the arcuate and the central sulcus. This zone corresponds to the cytochrome oxidase area F4 (Matelli, Luppino, and Rizzolatti: Behav. Brain Res. 18: 125-137, '85). The inferior area 6 also has topographically organized connections with the supplementary motor area. The inferior area 6 receives and sends fibers to a series of discrete cortical areas located in the lower cortical moiety (Sanides: The Structure and Function of the Nervous Tissue, Vol. 5. New York: Academic Press, pp 329-453, '72). These areas that form a broad ring around the central sulcus are the ventral bank of the principal sulcus and the adjacent area 46, the precentral operculum (PrOC), area SII (Jones and Burton: J. Comp. Neurol. 168:197-248, '76), the parietal operculum, and the rostral part of the inferior parietal lobule including the lower bank of the intraparietal sulcus. Finally, the inferior area 6 has sparse but consistent connections with insular and cingulate cortices. The functional significance of this complex pattern of connections is discussed.
无颗粒额叶皮质（6区）的嘴侧部分可根据其细胞结构、酶学特性及连接情况分为两个大的区域：一个位于弓形沟嵴内侧的上部区域，以及一个位于其外侧的下部区域。在本研究中，我们通过将少量与辣根过氧化物酶结合的小麦胚芽凝集素（WGA-HRP）和荧光示踪剂（快蓝和双脒基黄）注入6区下部区域的特定部位以及4区的生理确定区域，追踪了6区下部区域的传入和传出连接。6区下部区域与4区之间存在有序的拓扑连接模式。弓形沟嵴附近的区域（手部区域）投射到4区的手部区域，而6区下部区域外侧部分（嘴部区域）则与4区的相应区域相连。然而，这两个区域之间连接的组织方式有所不同。6区和4区的手部区域有直接的相互投射，而后弓形皮质中的嘴部区域则通过弓形沟和中央沟之间的一个中间区域将信息传递至4区。该区域对应于细胞色素氧化酶F4区（马特利、卢皮诺和里佐拉蒂：《行为脑研究》18: 125 - 137, '85）。6区下部区域与辅助运动区也有拓扑组织化的连接。6区下部区域接收并向位于皮质下部的一系列离散皮质区域发送纤维（萨尼德斯：《神经组织的结构与功能》，第5卷。纽约：学术出版社，第329 - 453页，'72）。这些围绕中央沟形成一个宽环的区域包括中央沟主沟的腹侧缘和相邻的46区、中央前岛盖（PrOC）、SII区（琼斯和伯顿：《比较神经学杂志》168:197 - 248, '76）、顶岛盖以及顶下小叶的嘴侧部分，包括顶内沟的下缘。最后，6区下部区域与岛叶和扣带回皮质有稀疏但稳定的连接。本文讨论了这种复杂连接模式的功能意义。
