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

Anneka Joachimsthaler,Jan Kremers,Tina Tsai

doi:10.3390/vision1040023

Anneka Joachimsthaler, Jan Kremers + Show 1 more

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https://doi.org/10.3390/vision1040023

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Abstract

To date, most studies involving in vivo electroretinography in mice are performed on steady state adapted animals. In this study, we focused on the dynamics of adaptation to high and low light levels in the mouse retina. Two flash electroretinogram (ERG) protocols and one flicker ERG protocol were employed. In the two flash ERG protocols, the animals were adapted to either 25 or 40 cd/m2 white light and ERGs were recorded for up to 15 min of adaptation. Afterwards, flash ERGs were recorded for up to 45 min of dark adaptation. Amplitudes of the flash ERG increased during light adaptation, while implicit times of the different wave components decreased. During subsequent dark adaptation, the amplitudes further increased. The increase in a-to-b-wave ratio indicated adaptational processes at the photoreceptor synapse. In the flicker ERG protocol, the responses to 12 Hz sinusoidal luminance modulation during the adaptation to 25 cd/m2 and a 1 cd/m2 mean luminances were recorded. The amplitudes of the first harmonic components in the flicker protocol decreased during light adaptation but increased during dark adaptation. This is at odds with the changes in the flash ERG, indicating that adaptation may be different in different retinal pathways.

Highlights

The electroretinogram (ERG) is a non-invasive in vivo electrophysiological method that enables the analysis of physiology and the functional integrity of the retina
The components were rather small in amplitude compared to those recorded during steady state light adaptation
All animal experiments were performed in accordance with the principles regarding the care and use of animals adopted by the Association for Research in Vision and Ophthalmology and the Society for Neuroscience, and complied with the guidelines for the welfare of experimental animals issued by the Federal Government of Germany and the University of Erlangen–Nürnberg

Summary

Introduction

The electroretinogram (ERG) is a non-invasive in vivo electrophysiological method that enables the analysis of physiology and the functional integrity of the retina. When the white adapting light, prior to the dark adaptation period, was 25 cd/m2 (protocol 1), responses to two flashes were recorded and averaged. The measurements were repeated every 30 s (first measurement directly after offset of the white background) during the first 4 min. Thereafter, the responses to four flashes were averaged and recorded every 60 s. After the 40 cd/m2 white adaptation (protocol 2), responses to one flash were measured every 60 s (first measurement started 5 s after offset of the white background) for the first 4 min, followed by a period where the averaged responses to two flashes were measured every 120 s. The ERG responses did not change strongly, indicating that the recordings were stable and any change in ERGs afterwards were caused by the adaptation paradigms

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