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

Fukuda Y, Higuchi S, Yasukouchi A, Morita T - J Physiol Anthropol (2012)

Bottom Line: Two 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).Implicit time of the first peak was much longer than that to the b-wave and this delay might reflect mRGC's sluggish responses.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Living Environmental Science, Fukuoka Women's University, 1-1-1, Kasumigaoka, Higashi-ku, Fukuoka 813-8529, Japan. fukuda@fwu.ac.jp

ABSTRACT

Background: The 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).

Methods: In 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.

Results: Two 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).

Conclusions: Implicit 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.

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A diagram illustrating the experimental set-up, the integrating sphere exposure and the monitor array.
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Figure 1: A diagram illustrating the experimental set-up, the integrating sphere exposure and the monitor array.

Mentions: Figure1 illustrates the apparatus used in the experiment. A personal computer controlled the four-primary illumination system [9]. It consisted of an optical diffuser and an integrating sphere. Four types of light-emitting diode (LED; peak wavelengths: 633 nm, 593 nm, 508 nm and 468 nm; and half-height bandwidth: 13 to 32 nm) were used. The light emitted from four types of LED, which were embedded in the inner wall of the integrating sphere, projected as the internally-synthesized test stimuli. The luminance output of each LED was controlled by both pulse-width modulation units and an embedded controller (H8/3052, Renesas Technology, Tokyo, Japan). A detailed description of the illumination system has previously been published [9,11].


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

Fukuda Y, Higuchi S, Yasukouchi A, Morita T - J Physiol Anthropol (2012)

A diagram illustrating the experimental set-up, the integrating sphere exposure and the monitor array.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475092&req=5

Figure 1: A diagram illustrating the experimental set-up, the integrating sphere exposure and the monitor array.
Mentions: Figure1 illustrates the apparatus used in the experiment. A personal computer controlled the four-primary illumination system [9]. It consisted of an optical diffuser and an integrating sphere. Four types of light-emitting diode (LED; peak wavelengths: 633 nm, 593 nm, 508 nm and 468 nm; and half-height bandwidth: 13 to 32 nm) were used. The light emitted from four types of LED, which were embedded in the inner wall of the integrating sphere, projected as the internally-synthesized test stimuli. The luminance output of each LED was controlled by both pulse-width modulation units and an embedded controller (H8/3052, Renesas Technology, Tokyo, Japan). A detailed description of the illumination system has previously been published [9,11].

Bottom Line: Two 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).Implicit time of the first peak was much longer than that to the b-wave and this delay might reflect mRGC's sluggish responses.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Living Environmental Science, Fukuoka Women's University, 1-1-1, Kasumigaoka, Higashi-ku, Fukuoka 813-8529, Japan. fukuda@fwu.ac.jp

ABSTRACT

Background: The 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).

Methods: In 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.

Results: Two 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).

Conclusions: Implicit 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.

Show MeSH
Related in: MedlinePlus