Purpose

Human oscillatory potentials (OPs) are derived from dark-adapted (DA) electroretinograms (ERGs) with fixed frequency cutoff filters while light-adapted (LA) OPs are generally not isolated from ERGs. Our purpose was to analyze the effect of cutoff frequencies on DA and LA ERG components using a series of fixed and variable filters.

Methods

DA and LA ERGs were recorded from 10 healthy eyes of 10 subjects (mean age = 20.5 ± 6.7 years) following ISCEV standards. Each signal was filtered in the Fourier domain to acquire slow (a- and b-waves; below cutoff frequency) and fast (OPs; above cutoff frequency) components. Fixed cutoff frequencies ranged from 60 to 105 Hz and a variable cutoff frequency was calculated. Results were analyzed with statistical tests and specific models.

Results

DA ERG components were slightly influenced by the filter cutoff frequency. In contrast, fixed and variable filters significantly changed LA components: the lower the cutoff frequency the smaller the b-wave and OP3 and the higher the OP2/OP4 amplitudes. Analyzing the filter frequency limits a transition range between 68.9 Hz and 83.9 Hz was observed where amplitudes vary.

Conclusions

The present report shows that DA OPs may be isolated from ERGs using filtering procedures with high-pass cutoff frequency at about 75 Hz as recommended by ISCEV. On the other hand, the spectral distribution of low-frequency and high-frequency LA ERG components may overlap. Accordingly, filtering the signal using different cutoff frequencies is not necessarily separating b-wave and OPs.

中文翻译：

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固定截止滤波对暗适应和光适应ERG分量的影响及可变截止滤波的应用

目的

人体振荡电位 (OPs) 源自具有固定频率截止滤波器的暗适应 (DA) 视网膜电图 (ERG)，而光适应 (LA) OP 通常不与 ERG 隔离。我们的目的是使用一系列固定和可变滤波器分析截止频率对 DA 和 LA ERG 分量的影响。

方法

按照 ISCEV 标准，从 10 名受试者（平均年龄 = 20.5 ± 6.7 岁）的 10 只健康眼睛中记录 DA 和 LA ERG。在傅立叶域中对每个信号进行滤波，以获取慢速（a 波和 b 波；低于截止频率）和快速（OPs；高于截止频率）分量。固定截止频率范围为 60 至 105 Hz，并计算了可变截止频率。使用统计检验和特定模型对结果进行分析。

结果

DA ERG 分量受滤波器截止频率的轻微影响。相比之下，固定和可变滤波器显着改变了 LA 分量：截止频率越低，b 波和 OP3 越小，OP2/OP4 幅度越高。分析滤波器频率限制了 68.9 Hz 和 83.9 Hz 之间的过渡范围，其中幅度变化。

结论

本报告显示 DA OP 可以使用 ISCEV 推荐的高通截止频率约为 75 Hz 的滤波程序与 ERG 分离。另一方面，低频和高频 LA ERG 分量的频谱分布可能重叠。因此，使用不同截止频率对信号进行滤波不一定将 b 波和 OP 分开。