Gray C M, Engel A K, König P, Singer W
Max-Planck-Institute fur Hirnforschung, Frankfurt a.M., Germany.
Vis Neurosci. 1992 Apr;8(4):337-47. doi: 10.1017/s0952523800005071.
Previously, we have demonstrated that a subpopulation of visual cortical neurons exhibit oscillatory responses to their preferred stimuli at a frequency near 50 Hz (Gray & Singer, 1989). These responses can selectively synchronize over large distances of cortex in a stimulus-specific manner (Gray et al., 1989; Engel et al., 1990 alpha). Here we report the results of a new analysis which reveals the fine temporal structure inherent in these interactions. We utilized pairs of recordings of the local field potential (LFP) activity from area 17 in the anesthetized cat which met two criteria. The LFP was correlated with the underlying unit activity at each site and the recording sites were at least 5 mm apart in cortex. A moving-window technique was applied to compute cross correlograms on 100-ms epochs of data repeated at intervals of 30 ms for a period of 3 s during each direction of stimulus movement. A statistical test was devised to determine the significance of detected correlations. In this way we were able to determine the magnitude, phase difference, frequency, and duration of correlated oscillations as a function of time. The results demonstrate that (1) the duration of synchrony is variable and lasts from 100-900 ms; (2) the phase differences between and the frequencies of synchronized responses are also variable within and between events and range from +3 to -3 ms and 40-60 Hz, respectively; and (3) multiple correlation events often occur within a single stimulus period. These results demonstrate a high degree of dynamic variability and a rapid onset and offset of synchrony among interacting populations of neurons which is consistent with the requirements of a mechanism for feature integration.
此前，我们已经证明，视觉皮层神经元的一个亚群对其偏好刺激会在接近50赫兹的频率上表现出振荡反应（格雷和辛格，1989年）。这些反应能够以刺激特异性的方式在皮层的大范围内选择性地同步（格雷等人，1989年；恩格尔等人，1990年α）。在此，我们报告一项新分析的结果，该分析揭示了这些相互作用中固有的精细时间结构。我们利用了来自麻醉猫17区的局部场电位（LFP）活动的成对记录，这些记录满足两个标准。局部场电位与每个位点的基础单位活动相关，并且记录位点在皮层中至少相距5毫米。应用移动窗口技术，在每个刺激运动方向上，以30毫秒的间隔重复100毫秒的数据段来计算互相关图，持续3秒。设计了一种统计测试来确定检测到的相关性的显著性。通过这种方式，我们能够确定相关振荡的幅度、相位差、频率和持续时间作为时间的函数。结果表明：（1）同步的持续时间是可变的，持续100 - 900毫秒；（2）同步反应之间的相位差和频率在事件内和事件间也都是可变的，分别在 +3到 -3毫秒和40 - 60赫兹范围内；（3）在单个刺激期内经常会发生多个相关事件。这些结果表明，在相互作用的神经元群体之间存在高度的动态变异性以及同步的快速起始和终止，这与特征整合机制的要求是一致的。
