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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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Preliminary results showing the ERG with light flux stimulus.
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Figure 3: Preliminary results showing the ERG with light flux stimulus.

Mentions: In order to assess validity of the ERG measurements, preliminary data from two subjects (females, 22 years old) were obtained with a light flux stimulus (often used in conventional ERG measurements). The light flux, with a maximum luminance of 1,132 cd/m2 for 100 msec, was given once to each subject after a 30-minute dark adaptation. The waveforms of the a- and b-waves were consistent with typical dark-adapted ERG characteristics with regard to implicit times: a-wave, about 20 msec; b-wave, about 50 msec (Figure3). The amplitudes of the a-wave and b-wave were approximately −15 μV and 50 to 80 μV, respectively.


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)

Preliminary results showing the ERG with light flux stimulus.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Preliminary results showing the ERG with light flux stimulus.
Mentions: In order to assess validity of the ERG measurements, preliminary data from two subjects (females, 22 years old) were obtained with a light flux stimulus (often used in conventional ERG measurements). The light flux, with a maximum luminance of 1,132 cd/m2 for 100 msec, was given once to each subject after a 30-minute dark adaptation. The waveforms of the a- and b-waves were consistent with typical dark-adapted ERG characteristics with regard to implicit times: a-wave, about 20 msec; b-wave, about 50 msec (Figure3). The amplitudes of the a-wave and b-wave were approximately −15 μV and 50 to 80 μV, respectively.

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