Song Xue-Mei, Li Chao-Yi
Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Cereb Cortex. 2008 Feb;18(2):331-6. doi: 10.1093/cercor/bhm057. Epub 2007 May 10.
Recent studies have reported that the size of the classical receptive field (CRF) and the extent of spatial summation of V1 neurons depend on stimulus contrast. We reexamined these properties for 48 V1 neurons in the cat and found that all the cells had a constant CRF size, whereas their spatial summation properties can be contrast dependent (CD) or contrast independent (CID). Of the 29 CD cells, 17 showed facilitatory summation at low contrast (10%), but suppressive summation at high contrast (80%); the other 12 showed weak suppressive summation at low contrast, whereas the strength of suppression increased significantly at high contrast. The 19 CID cells showed similar facilitative (CIDf) or suppressive (CIDs) summation at low and high contrast, without changes in shape and/or peak location. We successfully labeled 11 CD cells and 10 CID cells with biocytin. The morphological results demonstrated that all the labeled CD cells were pyramidal cells, whereas all labeled CID cells were nonpyramidal cells, in which the CIDf cells were spiny stellates and the CIDs cells, smooth interneurons. There is thus a global distinction between summation properties of pyramidal and nonpyramidal cells, and between the smooth and spiny nonpyramidal cells as well.
最近的研究报告称，经典感受野（CRF）的大小以及V1神经元的空间总和程度取决于刺激对比度。我们重新检查了猫的48个V1神经元的这些特性，发现所有细胞的CRF大小恒定，而它们的空间总和特性可能依赖于对比度（CD）或不依赖于对比度（CID）。在29个CD细胞中，17个在低对比度（10%）时表现出易化性总和，但在高对比度（80%）时表现出抑制性总和；另外12个在低对比度时表现出弱抑制性总和，而在高对比度时抑制强度显著增加。19个CID细胞在低对比度和高对比度时表现出相似的易化性（CIDf）或抑制性（CIDs）总和，形状和/或峰值位置没有变化。我们用生物素成功标记了11个CD细胞和10个CID细胞。形态学结果表明，所有标记的CD细胞都是锥体细胞，而所有标记的CID细胞都是非锥体细胞，其中CIDf细胞是棘状星型细胞，CIDs细胞是平滑中间神经元。因此，锥体细胞和非锥体细胞的总和特性之间存在整体差异，平滑和棘状非锥体细胞之间也存在差异。
