Robson J A, Hall W C
J Comp Neurol. 1977 May 15;173(2):355-88. doi: 10.1002/cne.901730210.
The posterior neocortex in the grey squirrel, Sciurus carolinensis, includes an extensive region which receives projections from the pulvinar. Previous studies have demonstrated that this cortical region can be subdivided on the basis of differences in cytoarchitecture and electrophysiologically defined representations of the visual field. The main purpose of the present paper was to determine whether these cortical subdivisions could be related to corresponding subdivisions in the pulvinar. The methods used to trace connections included anterograde degeneration, anterograde axonal transport of tritiated amino acids and the retrograde axonal transport of horseradish peroxidase. The results indicate that the pulvinar in this species contains at least three main subdivisions which can be distinguished by their cytoarchitecture and their patterns of connections. A caudal subdivision contains large, evenly-spaced neurons and receives bilateral input from the superficial, retinal-recipient layers of the superior colliculus. This caudal subdivision has reciprocal interconnections with a cytoarchitectonically distinct area in the temporal cortex. A rostro-lateral subdivision contains smaller, more lightly stained neurons which tend to form clusters. This subdivision receives only ipsilateral tectal input and projects to occipital area 18. This subdivision does not receive input from areas 17, 18, and 19, or from the temporal cortex. Finally, a rostro-medial subdivision is cytoarchitectonically similar to the rostro-lateral subdivision but receives little, if any, input from the superior colliculus. This rostro-medial area does, however, receive corticofugal projections from occipital areas 17, 18, and 19, and projects to area 19. These patterns of connections suggest that each of these subdivisions has close associations with the visual system. The question of whether similar subdivision are present in the visual thalamus of other species is discussed.
灰松鼠（Sciurus carolinensis）的后新皮质包含一个广泛的区域，该区域接受来自丘脑枕的投射。先前的研究表明，这个皮质区域可以根据细胞结构的差异以及视野的电生理定义表征进行细分。本文的主要目的是确定这些皮质细分是否与丘脑枕中的相应细分相关。用于追踪连接的方法包括顺行性变性、氚标记氨基酸的顺行轴突运输以及辣根过氧化物酶的逆行轴突运输。结果表明，该物种的丘脑枕至少包含三个主要细分，可通过其细胞结构和连接模式加以区分。一个尾侧细分包含大的、间距均匀的神经元，并接受来自上丘浅表视网膜接受层的双侧输入。这个尾侧细分与颞叶皮质中一个细胞结构不同的区域有相互连接。一个 rostro - lateral 细分包含较小的、染色较浅的神经元，这些神经元倾向于形成簇。这个细分仅接受同侧顶盖输入，并投射到枕叶 18 区。这个细分不接受来自 17、18 和 19 区或颞叶皮质的输入。最后，一个 rostro - medial 细分在细胞结构上与 rostro - lateral 细分相似，但几乎不接受来自上丘的输入（如果有的话）。然而，这个 rostro - medial 区域确实接受来自枕叶 17、18 和 19 区的皮质离心投射，并投射到 19 区。这些连接模式表明，这些细分中的每一个都与视觉系统有密切关联。本文还讨论了其他物种的视觉丘脑是否存在类似细分的问题。
