TY - JOUR
T1 - Properties of rat cone-mediated electroretinograms during light adaptation
AU - Goto, Yoshinobu
AU - Tobimatsu, Shozo
AU - Shigematsu, Junya
AU - Akazawa, Kohei
AU - Kato, Motohiro
N1 - Funding Information:
The authors thank Neal S. Peachey, Ph.D. and Mitchell G. Brigell, Ph.D. for their comments on this manuscript. We also thank Dr. Brian Quinn for checking the English of this manuscript. This study was partly supported by Kaibara Morikazu Medical Science Promotion Foundation.
PY - 1999/9
Y1 - 1999/9
N2 - Purpose. 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. Methods. 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/m2) with a combination of 3 stimulus flash intensities (0.86, 1.30 or 2.03 log cd sec/m2). The responses were obtained at 2 minute intervals for 25 minutes of light adaptation. Results. 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. Conclusions. 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.
AB - Purpose. 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. Methods. 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/m2) with a combination of 3 stimulus flash intensities (0.86, 1.30 or 2.03 log cd sec/m2). The responses were obtained at 2 minute intervals for 25 minutes of light adaptation. Results. 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. Conclusions. 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.
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U2 - 10.1076/ceyr.19.3.248.5313
DO - 10.1076/ceyr.19.3.248.5313
M3 - Article
C2 - 10487963
AN - SCOPUS:0032748940
SN - 0271-3683
VL - 19
SP - 248
EP - 253
JO - Current Eye Research
JF - Current Eye Research
IS - 3
ER -