Mesopic and Photopic Rod and Cone Photoreceptor-Driven Visual Processes in Mice With Long-Wavelength–Shifted Cone Pigments

Abstract

Employing the silent substitution method with stimuli of appropriate luminance on the LIAIS mouse (as on human observers) increases the specificity, robustness, and scope to which photoreceptor-driven responses can be reliably assayed compared to the standard photoreceptor isolation methods.

Electrophysiological Studies on The Dynamics of Luminance Adaptation in the Mouse Retina

“…This large phase change is possibly caused by a change from cone- to rod-driven responses and vice versa. Recently, we indeed found that the rod-driven responses are particularly large at luminances below approximately 7 cd/m 2 and mainly cone-driven for higher mean luminances [40]. Again, the phase changes described here for mice, are not consistent with previous findings for human subjects.…”

“…However, the mutations lead to structural changes in the retina which probably also affect the ERG recordings. A third possibility to examine rod- and cone-mediated responses separately would be by using the silent substitution method, in animals that have L/M cone pigments with long wavelength-shifted absorption spectra [1,40,48,49]. In contrast to the other mouse mutants, these animals can be considered to be physiologically normal.…”

Mouse Cones Adapt Fast, Rods Slowly In Vivo

“…Figure 5B shows the first harmonic amplitudes of the 8-and 12-Hz responses plotted versus recording time, showing that generally the responses to 8-Hz stimuli were larger than those to 12-Hz stimuli over the whole recording period (directly after luminance increase to 8.8 cd/m 2 : P ¼ 0.034, unpaired t-test; after 10 minutes of 8.8 cd/m 2 : P ¼ 0.030, unpaired t-test; directly after luminance decrease to 0.4 cd/m 2 : P ¼ 0.344, unpaired t-test; after 32 minutes of 0.4 cd/m 2 : P ¼ 0.040, unpaired t-test; see Table 4). This is agreement with previous data, 11 where it was found that rod-and cone-driven responses have low pass characteristics (more pronounced in rod-driven than in cone-driven responses).…”

“…However, the luminance levels were deliberately chosen so the responses driven by cones (at 0.4 cd/m 2 ) and rods (at 8.8 cd/ m 2 ) were negligible at steady state. 11 Therefore, with these luminances, interactions between rod-and cone-driven signals are not expected. At intermediate luminances, combined rodand cone-driven responses can be expected.…”

“…Most ERG studies are performed at a steady adaptation state. [11][12][13][14][15][16][17][18][19][20] The dynamics of adaptation in ERG responses has not been studied intensively in vivo. In most of these studies, the alterations in responses to single flashes or trains of flashes were described.…”