Ferster D
J Neurosci. 1987 Jun;7(6):1780-91. doi: 10.1523/JNEUROSCI.07-06-01780.1987.
According to current theory, orientation selectivity in cortical simple cells is critically dependent on intracortical synaptic inhibition. In particular, it is thought that IPSPs evoked by stimuli of the nonpreferred orientation are required to prevent a neuron from responding to a broadly tuned excitatory input at any but the preferred orientation. Yet EPSPs recorded in simple cells are in themselves highly orientation-selective. How is this possible, when excitation arises primarily from relay cells of the lateral geniculate nucleus (LGN), which are largely insensitive to orientation? In this paper, the properties of EPSPs are compared with the predictions of a model of geniculate excitation of simple cells. The model, which is derived from the suggestions of Hubel and Wiesel (1962), relies on the now familiar arrangement of the receptive fields of presynaptic geniculate cells into lines parallel to the axis of orientation of the postsynaptic cell. Several properties of the EPSPs observed in simple cells, and the orientation tuning of simple cells observed in extracellular experiments, can be accounted for without resorting to intracortical inhibition.
根据当前理论，皮层简单细胞的方向选择性关键取决于皮层内突触抑制。具体而言，人们认为非偏好方向刺激引发的抑制性突触后电位（IPSP）对于防止神经元在除偏好方向以外的任何方向对广泛调谐的兴奋性输入产生反应是必需的。然而，在简单细胞中记录到的兴奋性突触后电位（EPSP）本身就具有高度的方向选择性。当兴奋主要源于外侧膝状体核（LGN）的中继细胞，而这些中继细胞在很大程度上对方向不敏感时，这怎么可能呢？在本文中，将EPSP的特性与简单细胞膝状体兴奋模型的预测进行了比较。该模型源自Hubel和Wiesel（1962）的观点，依赖于现在熟知的将突触前膝状体细胞的感受野排列成与突触后细胞方向轴平行的线。在简单细胞中观察到的EPSP的几个特性，以及在细胞外实验中观察到的简单细胞的方向调谐，可以在不诉诸皮层内抑制的情况下得到解释。
