Saini K, Kretz R, Rager G
J Comp Neurol. 1987 May 1;259(1):31-49. doi: 10.1002/cne.902590104.
We used the rapid Golgi and horseradish peroxidase (HRP) techniques to study the dendritic spread of relay neurons in functionally distinct laminae of the tree shrew dorsal lateral geniculate nucleus (LGNd). On the basis of their dendritic spread in relation to laminar and interlaminar zones, we describe three classes of relay neurons. Unilaminar neurons with multipolar radiate, bitufted, and intermediate types of dendrites. Dendrites of these neurons are confined to one lamina only, but also can have some of their segments in adjacent interlaminar zones. Multilaminar neurons with multipolar radiate, bitufted, and intermediate types of dendrites. Independent of the site of their cell bodies in a laminar or interlaminar zone, these neurons spread their dendrites over two or more laminae. Interlaminar neurons whose cell bodies and dendrites are confined to a single interlaminar zone. Unilaminar neurons are found in all the laminae. In the medial three laminae, they are more of the radiate type, whereas in laminae 4 and 5 their dendrites tend to be more of a tufted nature. Lamina 6 shows a preponderance of the elongated bitufted type. Multilaminar neurons, although less common as compared to the unilaminar, are also observed in all the laminae. Some neurons have their dendrites confined to an interlaminar zone. By retrograde transport of HRP injected into the visual cortex, we have shown that these neurons are, in fact, relay neurons. In addition to relay neurons, there are small interneurons with "axoniform" dendrites and an unmyelinated axon whose arborization is confined within the limits of the neuron's dendritic spread. Neurons of this type are not labeled with HRP injected into the visual cortex. We conclude that although each lamina is functionally specialized by input from ipsilateral or contralateral retina and by segregation of neurons responding to on or off stimuli, some multilaminar neurons can be found in each lamina. Thus, laminar as well as interlaminar zones contain a class of neurons that could provide a cross-talk between the functionally specialized laminae. Most relay neurons in all the laminae, however, confine their dendrites to their home lamina. Thus, the dendritic architecture of relay neurons allows for processing of information both within channels and between channels.
我们运用快速高尔基染色法和辣根过氧化物酶（HRP）技术，研究树鼩背外侧膝状核（LGNd）功能不同层中中继神经元的树突分布。根据它们在层内和层间区域的树突分布情况，我们描述了三类中继神经元。单层层神经元，具有多极辐射状、双簇状和中间型树突。这些神经元的树突仅局限于一层，但也可能有一些树突段位于相邻的层间区域。多层层神经元，具有多极辐射状、双簇状和中间型树突。无论其胞体位于层内还是层间区域的何处，这些神经元的树突都会延伸至两层或更多层。层间神经元，其胞体和树突局限于单个层间区域。单层层神经元在所有层中均有发现。在内侧的三层中，它们多为辐射型，而在第4层和第5层中，其树突往往更呈簇状。第6层中细长双簇状类型占优势。多层层神经元虽然比单层层神经元少见，但在所有层中也都能观察到。一些神经元的树突局限于层间区域。通过将HRP注入视皮层进行逆行运输，我们已表明这些神经元实际上是中继神经元。除了中继神经元外，还有小型中间神经元，其具有“轴突样”树突和无髓轴突，其分支局限于神经元树突分布的范围内。这类神经元不会被注入视皮层的HRP标记。我们得出结论，尽管每层在功能上通过同侧或对侧视网膜的输入以及对开或关刺激做出反应的神经元的分离而具有特异性，但在每层中都能发现一些多层层神经元。因此，层内以及层间区域都包含一类神经元，它们可以在功能特异的层之间提供相互交流。然而，所有层中的大多数中继神经元将其树突局限于其所在的层。因此，中继神经元的树突结构允许在通道内和通道间处理信息。
