Tanimoto Naoyuki, Seeliger Mathias W
Department of Ophthalmology, University Hospital Schleswig-Holstein, Kiel, Germany.
Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
Methods Mol Biol. 2018;1753:191-202. doi: 10.1007/978-1-4939-7720-8_13.
Electroretinography (ERG) is important for functional diagnostics of the retina. Types of information about retinal function obtainable by ERG differ depending on recording conditions, e.g., a combination of light stimulus and adaptation. In terms of stimulation, single-flash and flicker stimuli are frequently used because response properties have been well investigated, allowing an assessment of fundamental retinal functionality; for example, how photoreceptors and bipolar cells, including signal transmission between them, are affected under pathological conditions. Usually, ERGs are recorded with a nonzero lower cutoff frequency of amplifiers to avoid certain artifacts, and additionally, responses are averaged over time so that non-event-related signals are cancelled out. However, the improved signal quality is associated with a loss of information. Especially in steady-state flicker ERG, information about the absolute baseline of recordings is missing because the prestimulus baseline is not included on the recording trace as well as because a zero response is obtained in all cases in which the signal baseline stays constant for a sufficient amount of time. In other words, it is impossible to tell from the conventional flicker ERG whether a zero signal is obtained under conditions of maximal or no excitation of the visual system. In this chapter, we describe a direct current ERG protocol (featuring a lower cutoff frequency of zero) with repetitive single flashes mimicking conventional flicker that contains a defined onset. Using this recording protocol, it is possible to assess not only the absolute excitatory level of the retina but also the development of steady-state responses from the single flash response.
视网膜电图（ERG）对视网膜的功能诊断很重要。通过ERG可获得的有关视网膜功能的信息类型因记录条件而异，例如光刺激和适应的组合。在刺激方面，经常使用单次闪光和闪烁刺激，因为其反应特性已得到充分研究，有助于评估视网膜的基本功能；例如，在病理条件下光感受器和双极细胞如何受到影响，以及它们之间的信号传递情况。通常，记录ERG时放大器的下限截止频率不为零，以避免某些伪迹，此外，还会对反应进行时间平均，以便消除与事件无关的信号。然而，信号质量的提高伴随着信息的丢失。特别是在稳态闪烁ERG中，记录的绝对基线信息缺失，这是因为刺激前基线未包含在记录轨迹中，而且在信号基线在足够长的时间内保持恒定的所有情况下都得到零反应。换句话说，从传统的闪烁ERG中无法判断在视觉系统最大激发或无激发条件下是否获得零信号。在本章中，我们描述了一种直流ERG协议（下限截止频率为零），该协议使用重复的单次闪光模拟传统闪烁，且包含明确的起始点。使用这种记录协议，不仅可以评估视网膜的绝对兴奋水平，还可以从单次闪光反应评估稳态反应的发展情况。
