Werner Birgit, Cook Paul B, Passaglia Christopher L
Program in Neuroscience, Boston University, Boston, MA, USA.
J Neurophysiol. 2008 Aug;100(2):1087-97. doi: 10.1152/jn.90527.2008. Epub 2008 Jun 25.
The retina can respond to a wide array of features in the visual input. It was recently reported that the retina can even recognize complicated temporal input patterns and signal violations in the patterns. When a sequence of flashes was presented, ganglion cells exhibited a variety of firing profiles and many cells showed an "omitted stimulus response" (OSR), in which they fired strongly if a flash in the sequence was omitted. We examined the synaptic origins of the OSR by recording excitatory synaptic currents from ganglion cells in the salamander retina in response to periodic flash sequences. Consistent with previous spike recordings, ganglion cells exhibited an OSR in their current response and the OSR shifted in time with a change in flash frequency such that it could predict when the next flash should have occurred. Although the behavior may seem sophisticated, we show that a simple linear-nonlinear model with a spike threshold can account for the OSR in on ganglion cells and that the variety of complex firing profiles seen in other ganglion cells can be explained by adding contributions from the off pathway. We discuss the physiological and simulation results and their implications for understanding retinal mechanisms of visual information processing.
视网膜能够对视觉输入中的多种特征做出反应。最近有报道称，视网膜甚至能够识别复杂的时间输入模式并发出模式中的信号违规情况。当呈现一系列闪光时，神经节细胞表现出多种放电模式，许多细胞表现出“遗漏刺激反应”（OSR），即如果序列中的一次闪光被遗漏，它们会强烈放电。我们通过记录蝾螈视网膜中神经节细胞对周期性闪光序列的兴奋性突触电流，研究了OSR的突触起源。与之前的放电记录一致，神经节细胞在其电流反应中表现出OSR，并且OSR会随着闪光频率的变化而在时间上发生偏移，从而能够预测下一次闪光应该出现的时间。尽管这种行为看似复杂，但我们表明，一个具有放电阈值的简单线性 - 非线性模型可以解释ON神经节细胞中的OSR，并且通过添加OFF通路的贡献，可以解释在其他神经节细胞中看到的各种复杂放电模式。我们讨论了生理和模拟结果及其对理解视觉信息处理的视网膜机制的意义。
