Przybyszewski A W, Lankheet M J, van de Grind W A
Utrecht Biophysics Research Institute, The Netherlands.
Vision Res. 1993 May;33(7):861-75. doi: 10.1016/0042-6989(93)90069-9.
Intracellularly recorded light-responses of X-type ganglion cells in the cat retina were separated, with the help of a wavelet method, into "slow" membrane ("G")-potentials and the corresponding spike trains. In response to sinusoidally modulated high intensity light spots with different sizes and frequencies, X-type ganglion cells show both oscillations correlated with the stimulus frequency and other, faster, oscillations that were not always locked to the stimulus. A forced van der Pol oscillator model with stimulus-dependent coefficients proved to describe the empirical findings quite well. A linearity-coefficient of the equations indicates strong nonlinearity at a temporal frequency of 8 Hz with spot sizes on the order of 0.5-0.7 deg and decreasing nonlinearity at lower temporal frequencies or smaller spot sizes, while the faster oscillations become more prominent. We could not determine whether the oscillations are intrinsic to the cell-membrane or generated by (or in interaction with) the preganglionic retinal meshwork. The results show that X-cell spike-trains can contain oscillations that are not phase-locked to the stimulus and that are therefore virtually invisible after stimulus synchronous averaging. It is not likely that these retinal oscillations directly induce the well described oscillations in cat visual cortex, since they usually fall in a different frequency range.
在小波方法的帮助下，对猫视网膜中X型神经节细胞的细胞内记录光反应进行了分离，分为“慢”膜（“G”）电位和相应的尖峰序列。响应不同大小和频率的正弦调制高强度光斑时，X型神经节细胞既表现出与刺激频率相关的振荡，也表现出其他更快的振荡，这些振荡并不总是与刺激同步。一个具有依赖于刺激系数的强迫范德波尔振荡器模型被证明能很好地描述实验结果。方程的线性系数表明，在时间频率为8Hz、光斑大小约为0.5 - 0.7度时存在强非线性，而在较低时间频率或较小光斑大小时非线性降低，同时更快的振荡变得更加突出。我们无法确定这些振荡是细胞膜固有的，还是由视网膜神经节前网络产生的（或与之相互作用产生的）。结果表明，X细胞尖峰序列可能包含与刺激不同步的振荡，因此在刺激同步平均后实际上是不可见的。这些视网膜振荡不太可能直接诱发猫视觉皮层中描述详尽的振荡，因为它们通常处于不同的频率范围。
