Distinct responses of cones and melanopsin-expressing retinal ganglion cells in the human electroretinogram

Abstract

BackgroundThe discovery of the novel photoreceptor, melanopsin-expressing retinal ganglion cells (mRGCs), has raised researchers’ interest in photoreceptive tasks performed by the mRGC, especially in non-image-forming visual functions. In a prior study, we investigated the mRGC response to light stimuli independent of rods and cones with the four-primary illumination system, which modulates stimulus levels to the mRGC and cones independently, and mRGC baseline responses were recorded in the electroretinogram (ERG).MethodsIn the present study, we used the same illumination system to compare independent responses of the mRGC and cones in five subjects (mean ± SD age, 23.0 ± 1.7 years). The ERG waveforms were examined as direct measurements of responses of the mRGCs and cones to stimulation (250 msec). Implicit times (the time taken to peaks) and peak values from 30 stimuli given to each subject were analyzed.ResultsTwo distinct positive peaks appeared in the mRGC response, approximately 80 msec after the onset of the stimuli and 30 msec after their offset, while no such peaks appeared in the cone response. The response to the mRGC stimulus was significantly higher than that to the cone stimulus at approximately 80 msec (P < 0.05) and tended to be higher than the cone stimulus at approximately 280 msec (P = 0.08).ConclusionsImplicit time of the first peak was much longer than that to the b-wave and this delay might reflect mRGC’s sluggish responses. This is the first report of amplitudes and implicit time in the ERG from the response of the mRGC that is independent of rods and cones, and obtained using the four-primary illumination system.

Electrophysiological responses from intrinsically photosensitive retinal ganglion cells are diminished in glaucoma patients

“…The ERG illumination system was custom built (Fukuoka Women's University, Fukuoka, Japan) to achieve receptor-silent substitution, as described in detail elsewhere. 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 Briefly, this system consisted of an optical diffuser, a light-emitting diode (LED) projector and its controller, and a personal computer to acquire responses. The red, green, blue, and white LEDs had peak wavelengths of 635, 525, 460, and 445/555 nm, respectively, and were used to build the projector.…”

“…The electroretinogram (ERG) is an established electrophysiological technique to evaluate the activity of individual retinal components and structures, and we have provided data on the direct electrical responses of ipRGCs in previous studies. 21 , 22 Because the ipRGC population is very small and its response reflects the neural activities of other photoreceptors, rods, and cones, it is difficult to record and identify the components of the electrical response derived from ipRGCs. Taking these difficulties into consideration, we used the silent-substitution technique 23 , 24 , 25 , 26 , 27 , 28 in the present study, which enabled us to control stimulus levels to the ipRGC and cones based on calculations of the spectral power distribution and α-opic sensitivity curve.…”

Device for silent substitution excitation of melanopsin for human eye

“…Light stimuli are usually presented homogeneously over a given area of the retina, either in an annulus or in a given circle centered on the fovea or outside of the fovea. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] For silent substitution devices, instruments with Newtonian view are more common and are used in a larger number of studies than those with Maxwellian view. For the latter, out of five publications, three are based on the same instrumentation.…”

The Verriest Lecture: Visual properties of metameric blacks beyond cone vision

“…Isolating responses of one or another type of photoreceptor requires specific paradigms. The time taken to reach peak in the electroretinogram (ERG) from the responses of the ipRGCs significantly differs from that of rods and cones [5]. Nevertheless, due to overlap of spectral sensitivity for cones, rods, and melanopsin cells, assessing the relative contribution of the receptor types to image and nonimage visual functions is difficult.…”