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Related Experiment Video

Updated: Jul 9, 2026

Multifocal Electroretinograms

Multifocal Electroretinograms

Published on: December 4, 2011

The multifocal pattern electroretinogram (mfPERG) and cone-isolating stimuli.

Hana Langrová¹, Herbert Jägle, Eberhart Zrenner

¹University Eye Hospital, Hradec Králové, Czech RepublicCenter for Ophthalmology, University of Tübingen, Germany.

Visual Neuroscience

|December 21, 2007

Summary

This summary is machine-generated.

Retinal signals undergo gain adjustment at the ganglion cell layer, not the cortex. This study reveals the L:M cone ratio changes with eccentricity, suggesting a key role for retinal processing in color vision.

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Last Updated: Jul 9, 2026

Multifocal Electroretinograms

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Published on: December 4, 2011

Simultaneous ex vivo Functional Testing of Two Retinas by in vivo Electroretinogram System

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Transretinal ERG Recordings from Mouse Retina: Rod and Cone Photoresponses

Transretinal ERG Recordings from Mouse Retina: Rod and Cone Photoresponses

Published on: March 14, 2012

Area of Science:

Ophthalmology
Neuroscience
Vision Science

Background:

The number of L cones typically exceeds M cones in the human retina.
Normal color vision suggests a gain alteration of L- and M-cone signals before cortical analysis.
Previous research indicates this gain adjustment occurs post-retinal bipolar/amacrine cell layer but pre-cortex.

Purpose of the Study:

To investigate the topographical distribution of L- and M-cone activity at the retinal ganglion cell layer.
To determine the L:M cone amplitude ratio across different retinal eccentricities using multifocal pattern electroretinography (mfPERG).

Main Methods:

Utilized multifocal pattern electroretinography (mfPERG) with standard, L-cone isolating, and M-cone isolating stimuli.
Calculated the L:M cone amplitude ratio from mfPERG responses in 10 trichromats.
Analyzed both positive and negative waveform components and recorded single cone-modulated mfERGs.

Main Results:

In trichromats, the L:M cone amplitude ratio was near unity (medians 1.18 and 1.16) in the central 8 degrees of the retina.
In the peripheral retina (12.8–26 degrees), the ratio increased to 1.42 (positive component) and 1.37 (negative component).
Median L:M ratios ranged from 1.00–2.78 centrally and 1.29–2.78 peripherally, indicating higher ratios in eccentric locations.

Conclusions:

A significant gain adjustment of retinal signals occurs at the ganglion cell layer.
The L:M cone amplitude ratio is not uniform across the retina, being higher in peripheral areas.
These findings highlight the role of retinal processing, specifically at the ganglion cell level, in modulating cone signals for color vision.