Evaluation of micro Electroretinograms Recorded with Multiple Electrode Array to Assess Focal Retinal Function.

Momo Fujii,Genshiro A Sunagawa,Mineo Kondo,Michiko Mandai,Masayo Takahashi

doi:10.1038/srep30719

Abstract

Full-field electroretinograms (ERGs) are used to objectively assess the mass function of the retina, whereas focal ERGs are used to evaluate the focal retinal function. The purpose of this study was to determine the usefulness of a multiple electrode array (MEA) system for recording ex vivo micro ERGs (mERGs) together with multiunit spike responses of the retinal ganglion cells (RGCs) to assess focal retinal function in isolated mouse retinas. The a- and b-waves of the full-field ERGs were present in the mERG. The b-wave was blocked by L-AP4, an inhibitor of the mGluR6 receptor, and the OFF-component was blocked by exposure to PDA, an antagonist of ionotropic glutamate receptors, with a corresponding RGC responses. mERGs were also recorded from mice with progressive retinal degeneration, the C57BL/6J-Pde6brd1-2J/J (rd1) mice, from which conventional full-field ERGs are non-recordable. A blockade of the glutamate receptors indicated that the negative wave of rd1 mice do not originate from the photoreceptors but from the second or third order neurons. This technique of recording mERGs will be useful in assessing the focal properties of the retinas obtained from eyes with pathology and also to follow the recovery of the physiology of the retina in regenerative studies.

Highlights

In focusing the stimuli on focal areas in small eyes in situ and in eliminating the effects of stray light, recording mfERGs from mice and rats are still challenging
The results of an earlier study[16] and our study[17] demonstrated that an multiple electrode array (MEA) can be used to record focal ERGs from isolated mouse retinas. We showed that this method was more sensitive than full-field ERGs in detecting the acute alterations of the ERGs induced by methyl–N-nitrosourea in a mouse retinal degeneration model[17]
We determined which weight of anchor will be better to record stable and repeatable micro ERGs (mERGs) (Fig. 1a)

Summary

Introduction

In focusing the stimuli on focal areas in small eyes in situ and in eliminating the effects of stray light, recording mfERGs from mice and rats are still challenging. A multiple electrode array (MEA) system is an effective in vitro method of recording and studying focal neuronal networks and has been used in many research fields[5,6,7,8]. In the retina, this system has been used to assess the spontaneous and light-evoked retinal ganglion cell (RGC) activities[9,10,11,12,13,14,15]. The negative wave did not originate from the photoreceptors as normally observed in wild type retina, but from the OFF bipolar cells and/or third order neurons

Objectives

Methods

Results

Conclusion