Saam M, Eckhorn R
Biol Cybern. 2000 Jul;83(1):L1-9. doi: 10.1007/PL00022918.
Classical receptive fields (cRF) increase in size from the retina to higher visual centers. The present work shows how temporal properties, in particular lateral spike velocity and spike input correlation, can affect cRF size and position without visual experience. We demonstrate how these properties are related to the spatial range of cortical synchronization if Hebbian learning dominates early development. For this, a largely reduced model of two successive levels of the visual cortex is developed (e.g., areas V1 and V2). It consists of retinotopic networks of spiking neurons with constant spike velocity in lateral connections. Feedforward connections between level 1 and 2 are additive and determine cRF size and shape, while lateral connections within level 1 are modulatory and affect the cortical range of synchronization. Input during development is mimicked by spike trains with spatially homogeneous properties and a confined temporal correlation width. During learning, the homogeneous lateral coupling shrinks to limited coupling structures defining synchronization and related association fields (AF). The size of level-1 synchronization fields determines the lateral coupling range of developing level-1-to-2 connections and, thus, the size of level-2 cRFs, even if the feedforward connections have distance-independent delays. AFs and cRFs increase with spike velocity in the lateral network and temporal correlation width of the input. Our results suggest that AF size of V1 and cRF size of V2 neurons are confined during learning by the temporal width of input correlations and the spike velocity in lateral connections without the need of visual experience. During learning from visual experience, a similar influence of AF size on the cRF size may be operative at successive levels of processing, including other parts of the visual system.
经典感受野（cRF）从视网膜到更高视觉中枢，其大小逐渐增大。目前的研究表明，时间特性，特别是侧向尖峰速度和尖峰输入相关性，如何在没有视觉经验的情况下影响cRF的大小和位置。我们证明，如果赫布学习在早期发育中占主导地位，这些特性如何与皮质同步的空间范围相关。为此，构建了一个大幅简化的视觉皮质两个连续层次（如V1和V2区）的模型。它由在侧向连接中具有恒定尖峰速度的发放神经元的视网膜拓扑网络组成。第1层和第2层之间的前馈连接是相加性的，决定了cRF的大小和形状，而第1层内的侧向连接是调制性的，影响皮质同步范围。发育期间的输入由具有空间均匀特性和有限时间相关宽度的尖峰序列模拟。在学习过程中，均匀的侧向耦合收缩为定义同步和相关关联场（AF）的有限耦合结构。第1层同步场的大小决定了发育中的第1层到第2层连接的侧向耦合范围，从而决定了第2层cRF的大小，即使前馈连接具有与距离无关的延迟。AF和cRF随着侧向网络中的尖峰速度和输入的时间相关宽度而增加。我们的结果表明，V1的AF大小和V2神经元的cRF大小在学习过程中受到输入相关性的时间宽度和侧向连接中尖峰速度的限制，而无需视觉经验。在从视觉经验学习的过程中，AF大小对cRF大小的类似影响可能在包括视觉系统其他部分在内的连续处理层次上起作用。
