Purpose

To study the effect of stimulus size and temporal frequency on the relative contribution of luminance and L-/M-cone opponent signals in the ERG.

Methods

In four healthy, color normal subjects, ERG responses to heterochromatic stimuli with sinusoidal, counter-phase modulation of red and green LEDs were measured. By inverse variation of red and green contrasts, we varied luminance contrast while keeping L-/M-cone opponent chromatic contrast constant. The first harmonic components in the full field ERGs are independent of stimulus contrast at 12 Hz, while responses to 36 Hz stimuli vary, reaching a minimum close to isoluminance. It was assumed that ERG responses reflect L-/M-cone opponency at 12 Hz and luminance at 36 Hz. In this study, we modeled the influence of temporal frequency on the relative contribution of these mechanisms at intermediate frequencies, measured the influence of stimulus size on model parameters, and analyzed the second harmonic component at 12 Hz.

Results

The responses at all frequencies and stimulus sizes could be described by a linear vector addition of luminance and L-/M-cone opponent reflecting ERGs. The contribution of the luminance mechanism increased with increasing temporal frequency and with increasing stimulus size, whereas the gain of the L-/M-cone opponent mechanism was independent of stimulus size and was larger at lower temporal frequencies. Thus, the luminance mechanism dominated at lower temporal frequencies with large stimuli. At 12 Hz, the second harmonic component reflected the luminance mechanism.

Conclusions

The ERGs to heterochromatic stimuli can be fully described in terms of linear combinations of responses in the (magnocellular) luminance and the (parvocellular) L-/M-opponent retino-geniculate pathways. The non-invasive study of these pathways in human subjects may have implications for basic research and for clinical research.

中文翻译：

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时间频率和刺激大小对异色闪烁 ERG 中亮度和 L-/M-锥对抗机制的相对贡献的影响

目的

研究刺激大小和时间频率对 ERG 中亮度和 L-/M-cone 对立信号的相对贡献的影响。

方法

在四名健康、颜色正常的受试者中，测量了 ERG 对红色和绿色 LED 的正弦反相位调制对异色刺激的反应。通过红色和绿色对比度的反向变化，我们改变了亮度对比度，同时保持 L-/M-cone 对手色度对比度恒定。全场 ERG 中的一次谐波分量独立于 12 Hz 的刺激对比度，而对 36 Hz 刺激的响应各不相同，达到接近等亮度的最小值。假设 ERG 响应反映了 12 Hz 的 L-/M-锥体对立性和 36 Hz 的亮度。在这项研究中，我们模拟了时间频率对这些机制在中频的相对贡献的影响，测量了刺激大小对模型参数的影响，并分析了 12 Hz 的二次谐波分量。

结果

所有频率和刺激大小的响应都可以通过亮度和 L-/M-cone 对手反映 ERG 的线性向量相加来描述。亮度机制的贡献随着时间频率的增加和刺激大小的增加而增加，而 L-/M-锥对立机制的增益与刺激大小无关，并且在较低的时间频率下更大。因此，亮度机制在具有大刺激的较低时间频率下占主导地位。在 12 Hz 时，二次谐波分量反映了亮度机制。

结论

异色刺激的 ERG 可以用（大细胞）亮度和（小细胞）L-/M-对手视网膜原状通路中的响应的线性组合来充分描述。在人类受试者中对这些途径进行非侵入性研究可能对基础研究和临床研究产生影响。