Gilbert C D, Wiesel T N
J Neurosci. 1983 May;3(5):1116-33. doi: 10.1523/JNEUROSCI.03-05-01116.1983.
The intrinsic connections of the cortex have long been known to run vertically, across the cortical layers. In the present study we have found that individual neurons in the cat primary visual cortex can communicate over suprisingly long distances horizontally (up to 4 mm), in directions parallel to the cortical surface. For all of the cells having widespread projections, the collaterals within their axonal fields were distributed in repeating clusters, with an average periodicity of 1 mm. This pattern of extensive clustered projections has been revealed by combining the techniques of intracellular recording and injection of horseradish peroxidase with three-dimensional computer graphic reconstructions. The clustering pattern was most apparent when the cells were rotated to present a view parallel to the cortical surface. The pattern was observed in more than half of the pyramidal and spiny stellate cells in the cortex and was seen in all cortical layers. In our sample, cells made distant connections within their own layer and/or within another layer. The axon of one cell had clusters covering the same area in two layers, and the clusters in the deeper layer were located under those in the upper layer, suggesting a relationship between the clustering phenomenon and columnar cortical architecture. Some pyramidal cells did not project into the white matter, forming intrinsic connections exclusively. Finally, the axonal fields of all our injected cells were asymmetric, extending for greater distances along one cortical axis than along the orthogonal axis. The axons appeared to cover areas of cortex representing a larger part of the visual field than that covered by the excitatory portion of the cell's own receptive field. These connections may be used to generate larger receptive fields or to produce the inhibitory flanks in other cells' receptive fields.
长期以来，人们一直知道皮质的内在连接是垂直穿过皮质各层的。在本研究中，我们发现猫初级视觉皮质中的单个神经元能够在平行于皮质表面的方向上进行令人惊讶的远距离水平通信（可达4毫米）。对于所有具有广泛投射的细胞，其轴突场中的侧支呈重复簇状分布，平均周期为1毫米。通过将细胞内记录和辣根过氧化物酶注射技术与三维计算机图形重建相结合，揭示了这种广泛的簇状投射模式。当细胞旋转至呈现与皮质表面平行的视图时，簇状模式最为明显。在皮质中超过一半的锥体细胞和棘状星状细胞中观察到了这种模式，并且在所有皮质层中都可见。在我们的样本中，细胞在其自身层内和/或另一层内建立远距离连接。一个细胞的轴突在两层中具有覆盖相同区域的簇，较深层中的簇位于上层簇的下方，这表明簇状现象与皮质柱状结构之间存在关联。一些锥体细胞不投射到白质中，仅形成内在连接。最后，我们所有注射细胞的轴突场都是不对称的，沿着一个皮质轴的延伸距离比沿着正交轴的延伸距离更长。轴突似乎覆盖了代表比细胞自身感受野的兴奋部分所覆盖的更大视野部分的皮质区域。这些连接可能用于产生更大的感受野或在其他细胞的感受野中产生抑制侧翼。
