Holdefer R N, Norton T T
Department of Physiological Optics, School of Optometry, Medical Center, University of Alabama, Birmingham 35294, USA.
J Comp Neurol. 1995 Jul 31;358(3):401-13. doi: 10.1002/cne.903580307.
A laminar analysis of the receptive field properties of relay cells in the binocular region of the tree shrew dorsal lateral geniculate nucleus (LGN) found three main subdivisions. Lamina 1 (receiving ipsilateral eye input) and lamina 2 (contralateral) comprise a pair of layers that contain only ON-center neurons. Laminae 4 (contralateral) and 5 (ipsilateral) comprise a pair of layers with mostly OFF-center cells (86%). Laminae 3 and 6 (both contralaterally innervated) also form a distinct pair, although lamina 3 contains a mixture of cells with ON-centers (43%) or OFF-centers (57%), and lamina 6 contains mostly cells with ON-OFF centers and suppressive surrounds (81%). Cells located in the interlaminar zones resembled neurons in laminae 3 and 6. In comparison with the cells in the OFF-center laminae 4 and 5, the ON-center cells in laminae 1 and 2 had smaller, more elliptical receptive field centers with stronger responses to flashed visual stimuli. In addition, cells in the ipsilateral eye laminae 1 and 5 showed a greater change in center diameter, with eccentricity from the area centralis, than cells in the contralateral eye laminae 2 and 4. Principal components analysis using six receptive field properties (latency to optic chiasm stimulation, receptive field center diameter, maintained discharge rate, response onset latency, peak spike density, and phasic-tonic index) suggested that the cells in laminae 3 and 6 and the interlaminar zones are W-like. Principal components analysis of the same receptive field properties in laminae 1, 2, 4, and 5 did not reveal differences clearly related to X-like (parvocellular) and Y-like (magnocellular) categories. Ninety-seven percent of the cells tested for linearity of spatial summation in laminae 1, 2, 4, and 5 were linear. We conclude that the dominant organizational features of the tree shrew LGN are the ON-center, OFF-center, and W pairs of layers that project to different regions within the striate cortex.
对树鼩背外侧膝状核（LGN）双眼区域中继细胞的感受野特性进行分层分析，发现了三个主要亚区。第1层（接受同侧眼输入）和第2层（对侧眼输入）构成一对仅包含ON中心神经元的层。第4层（对侧眼输入）和第5层（同侧眼输入）构成一对主要为OFF中心细胞的层（86%）。第3层和第6层（均由对侧支配）也形成一个独特的对，尽管第3层包含ON中心细胞（43%）或OFF中心细胞（57%）的混合，而第6层主要包含具有ON-OFF中心和抑制性周边的细胞（81%）。位于层间区的细胞类似于第3层和第6层中的神经元。与OFF中心的第4层和第5层中的细胞相比，第1层和第2层中的ON中心细胞具有更小、更椭圆的感受野中心，对闪光视觉刺激的反应更强。此外，同侧眼第1层和第5层中的细胞与对侧眼第2层和第4层中的细胞相比，其中心直径随与中央凹的偏心度变化更大。使用六种感受野特性（视交叉刺激的潜伏期、感受野中心直径、持续放电率、反应起始潜伏期、峰值放电密度和相位-紧张性指数）进行主成分分析表明，第3层和第6层以及层间区的细胞为W样细胞。对第1、2、4和5层相同感受野特性进行主成分分析，未发现与X样（小细胞）和Y样（大细胞）类别明显相关的差异。在第1、2、4和5层中测试空间总和线性的细胞中有97%是线性的。我们得出结论，树鼩LGN的主要组织特征是投射到纹状体内不同区域的ON中心、OFF中心和W层对。
