König P, Engel A K, Roelfsema P R, Singer W
Max-Planck-Institut für Hirnforschung, Frankfurt, Germany.
Neural Comput. 1995 May;7(3):469-85. doi: 10.1162/neco.1995.7.3.469.
Recent work suggests that synchronization of neuronal activity could serve to define functionally relevant relationships between spatially distributed cortical neurons. At present, it is not known to what extent this hypothesis is compatible with the widely supported notion of coarse coding, which assumes that features of a stimulus are represented by the graded responses of a population of optimally and suboptimally activated cells. To resolve this issue we investigated the temporal relationship between responses of optimally and suboptimally stimulated neurons in area 17 of cat visual cortex. We find that optimally and suboptimally activated cells can synchronize their responses with a precision of a few milliseconds. However, there are consistent and systematic deviations of the phase relations from zero phase lag. Systematic variation of the orientation of visual stimuli shows that optimally driven neurons tend to lead over suboptimally activated cells. The observed phase lag depends linearly on the stimulus orientation and is, in addition, proportional to the difference between the preferred orientations of the recorded cells. Similar effects occur when testing the influence of the movement direction and the spatial frequency of visual stimuli. These results suggest that binding by synchrony can be used to define assemblies of neurons representing a coarse-coded stimulus. Furthermore, they allow a quantitative test of neuronal network models designed to reproduce physiological results on stimulus-specific synchronization.
近期的研究表明，神经元活动的同步化可能有助于定义空间分布的皮层神经元之间功能相关的关系。目前，尚不清楚这一假设在多大程度上与广泛支持的粗略编码概念相兼容，粗略编码假设刺激的特征由一群最优和次优激活细胞的分级反应来表示。为了解决这个问题，我们研究了猫视觉皮层17区最优和次优刺激神经元反应之间的时间关系。我们发现，最优和次优激活的细胞能够以几毫秒的精度同步它们的反应。然而，相位关系存在一致且系统的偏离零相位滞后的情况。视觉刺激方向的系统变化表明，最优驱动的神经元往往领先于次优激活的细胞。观察到的相位滞后线性依赖于刺激方向，此外，还与记录细胞的偏好方向之间的差异成正比。在测试视觉刺激的运动方向和空间频率的影响时也会出现类似的效应。这些结果表明，同步结合可用于定义代表粗略编码刺激的神经元集合。此外，它们还允许对旨在重现关于刺激特异性同步的生理结果的神经网络模型进行定量测试。
