Symonds L L, Rosenquist A C
J Comp Neurol. 1984 Oct 10;229(1):39-47. doi: 10.1002/cne.902290104.
The interconnections among visual areas in cat cortex were studied with respect to the specific laminae in which the cortically projecting neurons are located. Single injections of HRP were made through recording micropipettes into nine different visual areas. In 15 cortical areas the laminar distribution of neurons which were retrogradely filled with HRP was plotted. In this way we determined the laminar origins of the cortical projections to the nine separate cortical visual areas which were injected. There are three major observations. First, areas 17 and 18 are the only two visual areas in which layers II and III are the primary site of cortically projecting cells; in the other 13 areas the deeper layers of cortex provide a large percentage of such neurons. Second, within any one cortical area, cortically projecting neurons may be distributed among different layers; the specific layer depends upon the cortical target of those neurons. Third, any one cortical area receives projections from several different cortical layers, the specific layers being dependent upon the area from which the projection originates. An individual cortical area, therefore, contributes to several different cortical visual circuits, with each of these circuits defined by the laminar connections of its neurons.
针对猫皮层视觉区域中皮层投射神经元所在的特定层，对这些区域之间的相互连接进行了研究。通过记录微电极将HRP单次注射到九个不同的视觉区域。在15个皮层区域绘制了被HRP逆行填充的神经元的层状分布。通过这种方式，我们确定了向九个单独注射的皮层视觉区域进行皮层投射的层状起源。有三个主要观察结果。第一，17区和18区是仅有的两个视觉区域，其中II层和III层是皮层投射细胞的主要位点；在其他13个区域，皮层较深的层提供了很大比例的此类神经元。第二，在任何一个皮层区域内，皮层投射神经元可能分布在不同的层中；具体的层取决于这些神经元的皮层靶点。第三，任何一个皮层区域都接收来自几个不同皮层层的投射，具体的层取决于投射起源的区域。因此，一个单独的皮层区域参与了几个不同的皮层视觉回路，这些回路中的每一个都由其神经元的层状连接所定义。
