Winfield D A, Rivera-Dominguez M, Powell T P
Brain Res. 1982 Jan 7;231(1):19-32. doi: 10.1016/0006-8993(82)90004-x.
The termination of geniculocortical fibres within the different subdivisions of lamina IV in area 17 of the visual cortex of the monkey has been studied quantitatively with the electron microscope. In lamina IVC alpha the axon terminals of fibres coming from the magnocellular layers of the lateral geniculate nucleus (LGN) make significantly more synapses per bouton than those of fibres arising from the parvocellular layers and terminating in laminae IVA and IVC beta. In all parts of area 17 examined there was a clear difference in the relative proportions of multisynaptic geniculocortical boutons between the alpha and beta divisions of lamina IVC. Calculations have shown that a single cell in the magnocellular laminae of the LGN may make about 6 times as many synaptic contacts within lamina IV of the visual cortex than one in the parvocellular laminae. It has also been estimated that there are at least 500 million geniculocortical boutons, or 1200 million synapses, in lamina IVC alpha and 100 million boutons, 1200 million synapses, in lamina IVC beta for one hemisphere, giving an approximate total number of 1500 million boutons and 2400 million synapses.
利用电子显微镜对猴视觉皮层17区IV层不同亚层内膝状皮质纤维的终末进行了定量研究。在IVCα层，来自外侧膝状核大细胞层的纤维的轴突终末每个终扣形成的突触明显多于来自小细胞层并终止于IVA层和IVCβ层的纤维的轴突终末。在17区所有检查部位，IVC层α和β亚层之间多突触膝状皮质终扣的相对比例存在明显差异。计算表明，外侧膝状核大细胞层中的一个细胞在视觉皮层IV层内形成的突触联系数量可能是小细胞层中一个细胞的6倍左右。据估计，一个半球的IVCα层至少有5亿个膝状皮质终扣，即12亿个突触，IVCβ层有1亿个终扣，12亿个突触，膝状皮质终扣总数约为15亿个，突触总数约为24亿个。
