Goto Y, Tobimatsu S, Shigematsu J, Akazawa K, Kato M
Kyushu University Neurological Institute Department of Clinical Neurophysiology Fukuoka, Japan.
Curr Eye Res. 1999 Sep;19(3):248-53. doi: 10.1076/ceyr.19.3.248.5313.
Our aim was to better understand how to isolate the cone-mediated response in rats. Therefore, we studied the difference of ERGs in the course of light adaptation between 2 and 20 Hz stimulus frequencies.
A total of 90 rats divided into 18 different groups were used following overnight dark adaptation. ERGs were recorded against 3 different adapting field luminances (1.15, 1. 50 or 1.75 log cd/m(2)) with a combination of 3 stimulus flash intensities (0.86, 1.30 or 2.03 log cd sec/m( 2)). The responses were obtained at 2 minute intervals for 25 minutes of light adaptation.
The response of the rat cone ERG was large despite the small number of cones. The mean amplitude increased systematically from the dark-adapted value requiring more than 15 minutes to reach an asymptote at 2 Hz stimulation, but only 10 minutes at 20 Hz stimulation. The 2 Hz adaptation curves had biphasic pattern compared to the monophasic 20 Hz curve. This second increase in the amplitude at 2 Hz appeared at around 7-8 minutes as a function of adaptation time. This tendency was most evident when using a low adapting field luminance with a high flash intensity.
Our results suggest that the rods intrude much more during light adaptation at 2 Hz stimulation in rodents than in humans. Therefore, 20 Hz flicker stimulation can better isolate more the cone-mediated function than 2 Hz stimulation during the course of light adaptation in rats. Furthermore, the functional characteristics of the cone in rats may be different from that in humans.
我们的目的是更好地了解如何分离大鼠的视锥细胞介导的反应。因此，我们研究了在2至20赫兹刺激频率的光适应过程中视网膜电图（ERG）的差异。
90只大鼠被分为18个不同组，经过一夜暗适应后使用。在3种不同的适应场亮度（1.15、1.50或1.75 log cd/m²）下，结合3种刺激闪光强度（0.86、1.30或2.03 log cd·sec/m²）记录ERG。在光适应的25分钟内，每隔2分钟获取一次反应。
尽管大鼠视锥细胞数量较少，但其ERG反应较大。平均振幅从暗适应值开始系统性增加，在2赫兹刺激下需要超过15分钟达到渐近线，而在20赫兹刺激下仅需10分钟。与单相的20赫兹曲线相比，2赫兹的适应曲线呈双相模式。在2赫兹时，振幅的第二次增加出现在约7 - 8分钟，是适应时间的函数。当使用低适应场亮度和高闪光强度时，这种趋势最为明显。
我们的结果表明，在啮齿动物中，与人类相比，在2赫兹刺激的光适应过程中，视杆细胞的干扰要多得多。因此，在大鼠光适应过程中，20赫兹闪烁刺激比2赫兹刺激能更好地分离更多视锥细胞介导的功能。此外，大鼠视锥细胞的功能特性可能与人类不同。
