Sherman S M, Friedlander M J
Department of Neurobiology and Behavior, State University of New York, Stony Brook 11794-5230.
Exp Brain Res. 1988;73(2):384-92. doi: 10.1007/BF00248231.
Roughly 25% of the neurons in the A-laminae of the cat's lateral geniculate nucleus are local interneurons, while the remaining 75% are relay cells that project to the visual cortex. The interneurons form the focus of our study. The relay cells are either X or Y cells and are thereby integral links in the parallel and independent retino-geniculo-cortical X and Y pathways. Little is known about the response properties of interneurons, largely because it is difficult to identify them clearly during electrophysiological recording. However, they can be identified by morphological criteria. We thus studied their response properties by recording intracellularly from geniculate neurons to characterize them and then injecting them with horseradish peroxidase (HRP); the HRP labeling subsequently allowed us to distinguish relay cells from interneurons. In this manner, we studied 171 relay cells (83 X and 88 Y) and 15 interneurons. The response properties tested for each of the interneurons were indistinguishable from those of the relay X cells. We conclude that these interneurons are directly innervated by retinogeniculate X axons and are firmly embedded in the X pathway. We found no evidence for interneurons in the Y pathway.
猫外侧膝状核A层中约25%的神经元是局部中间神经元，其余75%是投射到视觉皮层的中继细胞。中间神经元是我们研究的重点。中继细胞要么是X细胞，要么是Y细胞，因此是平行且独立的视网膜 - 膝状体 - 皮层X和Y通路中的重要环节。人们对中间神经元的反应特性知之甚少，主要是因为在电生理记录过程中很难清晰地识别它们。然而，可以通过形态学标准来识别它们。因此，我们通过对膝状核神经元进行细胞内记录来研究它们的反应特性以对其进行表征，然后向它们注射辣根过氧化物酶（HRP）；随后的HRP标记使我们能够区分中继细胞和中间神经元。通过这种方式，我们研究了171个中继细胞（83个X细胞和88个Y细胞）和15个中间神经元。对每个中间神经元测试的反应特性与中继X细胞的反应特性没有区别。我们得出结论，这些中间神经元直接由视网膜 - 膝状体X轴突支配，并牢固地嵌入X通路中。我们没有发现Y通路中存在中间神经元的证据。
