Abstract
Purpose:
Electroretinography (ERG) is used to assess retinal function in disease as well as functional recovery following a therapeutic intervention. In these cases, vision-related retinal electrical activity may be rather low, and light-independent but event-related responses become influential in the recordings. Here, we examine the impact of ERG-like potentials triggered by the sound associated with the Xenon flash discharge in mice.
Methods:
Functionally normal wild-type mice (C57Bl/6), mice with rod function only (Cnga3-/-), mice lacking any photoreceptor function (Cnga3-/-rho-/-), and mice with no auditory function (Cdh23 vAlb/vAlb), were examined in vivo with Xenon flash ERG systems. In some of the experiments, event-related acoustic stimulation was suppressed with a white noise generator.
Results:
Small signals, featuring an initial a-wave like deflection at about 20 ms, and a subsequent b-wave like deflection peaking at about 40 ms after the flash, were present in different mouse lines under conditions where usually no ERG responses can be detected: in Cnga3-/- mice under photopic conditions, in C57Bl/6 mice at very low stimulus intensities under photopic conditions, and in Cnga3-/-rho-/- mice under both scotopic and photopic conditions. In contrast, such signals could not be elicited in Cdh23 vAlb/vAlb mice. Furthermore, by masking the click sound of the Xenon flash discharge using continuous white noise, we were able to suppress the event-related signals in a reversible manner.
Conclusions:
In this study, we identified non-visual but event-related signals that contribute to the ERG in mice. The waveform and timing of these signals suggests that they resemble auditory evoked potentials. This finding may be of particular importance for the analysis and interpretation of ERG data in mice with reduced light-evoked responses.
Keywords: 510 electroretinography: non-clinical •
689 retina: distal (photoreceptors, horizontal cells, bipolar cells)