Spekreijse H, van Dijk B W, Kalitzin S N, Vijn P C
The Netherlands Ophthalmic Research Institute, Department of Visual System Analysis, Amsterdam.
Ciba Found Symp. 1994;184:88-99; discussion 99-103, 120-8. doi: 10.1002/9780470514610.ch5.
Correlation images were derived from simultaneous recordings of 12 signals representing the synaptic activity at different layers of a column in cat visual cortex (area 18) and 12 signals representing the local average spiking activity at the same locations. Because the ongoing activity and the activity evoked by stroboscopic flashes yielded the same correlation image, ongoing activity is caused by an input to a column similar to flash-evoked activity and is thus not endogenous. Moving bar stimuli evoked bursts of oscillations (25-75 Hz band) in the correlation image. The rhythm of these oscillations was not related to any frequency component in the stimulus. In all correlation images we observed that synaptic activity in one layer resulted in simultaneous spiking activity in all layers with latency differences smaller than 2 ms (the sample interval used). Similar behaviour was observed in a simulation experiment where we 'realistically' modelled one column of visual cortex with 1000 three-compartmental neurons in 11 functional layers. When such a model column was tuned to yield a stable and excitable system with low ongoing activity, activation of any of the layers caused simultaneous activity in all 11 layers. Both the simulation and the experimental results suggest that a column can be regarded as a basic processing element sending the same information over all its outputs to other columns within the same cortical region, other visual areas and subcortical structures.
相关图像来自于对代表猫视觉皮层（18区）某一柱状结构不同层突触活动的12个信号以及代表相同位置局部平均脉冲发放活动的12个信号的同步记录。由于持续活动和频闪闪光诱发的活动产生了相同的相关图像，所以持续活动是由类似于闪光诱发活动的输入到柱状结构的信号引起的，因此不是内源性的。移动条形刺激在相关图像中诱发了振荡爆发（25 - 75赫兹频段）。这些振荡的节律与刺激中的任何频率成分均无关。在所有相关图像中，我们观察到一层中的突触活动会导致所有层同时出现脉冲发放活动，潜伏期差异小于2毫秒（所用的采样间隔）。在一个模拟实验中也观察到了类似行为，在该实验中，我们用11个功能层中的1000个三室神经元对视觉皮层的一个柱状结构进行了“逼真”建模。当这样一个模型柱状结构被调整以产生一个具有低持续活动的稳定且可兴奋的系统时，激活任何一层都会导致所有11层同时活动。模拟和实验结果均表明，一个柱状结构可被视为一个基本处理单元，它在其所有输出上向同一皮层区域内的其他柱状结构、其他视觉区域和皮层下结构发送相同的信息。
