Limits...
Feedback from horizontal cells to cones mediates color induction and may facilitate color constancy in rainbow trout.

Sabbah S, Zhu C, Hornsby MA, Kamermans M, Hawryshyn CW - PLoS ONE (2013)

Bottom Line: Color vision is most beneficial when the visual system is color constant and can correct the excitations of photoreceptors for differences in environmental irradiance.We found that the efficiency of color induction in the cone output and optic nerve decreased significantly with the inhibition of HC-cone feedback.Therefore, our findings suggest not only that color induction originates as a result of HC-cone feedback, but also that this effect of HC-cone feedback is further amplified at downstream retinal elements, possibly through feedback mechanisms at the inner plexiform layer.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Queen's University, Kingston, Ontario, Canada. shai_sabbah@brown.edu

ABSTRACT
Color vision is most beneficial when the visual system is color constant and can correct the excitations of photoreceptors for differences in environmental irradiance. A phenomenon related to color constancy is color induction, where the color of an object shifts away from the color of its surroundings. These two phenomena depend on chromatic spatial integration, which was suggested to originate at the feedback synapse from horizontal cells (HC) to cones. However, the exact retinal site was never determined. Using the electroretinogram and compound action potential recordings, we estimated the spectral sensitivity of the photoresponse of cones, the output of cones, and the optic nerve in rainbow trout. Recordings were performed before and following pharmacological inhibition of HC-cone feedback, and were repeated under two colored backgrounds to estimate the efficiency of color induction. No color induction could be detected in the photoresponse of cones. However, the efficiency of color induction in the cone output and optic nerve was substantial, with the efficiency in the optic nerve being significantly higher than in the cone output. We found that the efficiency of color induction in the cone output and optic nerve decreased significantly with the inhibition of HC-cone feedback. Therefore, our findings suggest not only that color induction originates as a result of HC-cone feedback, but also that this effect of HC-cone feedback is further amplified at downstream retinal elements, possibly through feedback mechanisms at the inner plexiform layer. This study provides evidence for an important role of HC-cone feedback in mediating color induction, and therefore, likely also in mediating color constancy.

Show MeSH
Waveforms for ERG of ASP-treated retina, and for ERG and CAP of saline-treated retina.(A) Waveforms of electroretinogram (ERG) of aspartate (ASP)-treated retina, (B) ERG of saline (S)-treated retina, and (C) compound action potential (CAP) of S-treated retina at increasing irradiance levels. Stimulus irradiance was incremented in 0.3 log unit steps. The ERG a-wave from ASP-treated retina was used to estimate the photoresponse of cones; the ERG b-wave from S-treated retina was used to estimate the light-evoked response of the output of cones; and the ON response of CAP from S-treated retina was used to estimate the light-evoked response of the optic nerve. Note that individual waveforms were vertically displaced for clarity of presentation. Horizontal thick lines indicate the time and duration of the light stimulus.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3672170&req=5

pone-0066216-g001: Waveforms for ERG of ASP-treated retina, and for ERG and CAP of saline-treated retina.(A) Waveforms of electroretinogram (ERG) of aspartate (ASP)-treated retina, (B) ERG of saline (S)-treated retina, and (C) compound action potential (CAP) of S-treated retina at increasing irradiance levels. Stimulus irradiance was incremented in 0.3 log unit steps. The ERG a-wave from ASP-treated retina was used to estimate the photoresponse of cones; the ERG b-wave from S-treated retina was used to estimate the light-evoked response of the output of cones; and the ON response of CAP from S-treated retina was used to estimate the light-evoked response of the optic nerve. Note that individual waveforms were vertically displaced for clarity of presentation. Horizontal thick lines indicate the time and duration of the light stimulus.

Mentions: Spectral sensitivity was measured at different processing stages in the retina of rainbow trout. Sensitivity of the photoresponse of cones was estimated from the ERG a-wave of retina treated with aspartate (ASP) in saline (Ringer's solution); the sensitivity of the output of cones was estimated from the ERG b-wave of saline-treated retina; and the sensitivity of the optic nerve was estimated from the ON response of the compound action potential (CAP) of the optic nerve, projecting from saline-treated retina. See Figure 1 for ERG waveforms recorded from ASP-treated and saline-treated retina, as well as for CAP waveforms recorded from the optic nerve projecting from saline-treated retina.


Feedback from horizontal cells to cones mediates color induction and may facilitate color constancy in rainbow trout.

Sabbah S, Zhu C, Hornsby MA, Kamermans M, Hawryshyn CW - PLoS ONE (2013)

Waveforms for ERG of ASP-treated retina, and for ERG and CAP of saline-treated retina.(A) Waveforms of electroretinogram (ERG) of aspartate (ASP)-treated retina, (B) ERG of saline (S)-treated retina, and (C) compound action potential (CAP) of S-treated retina at increasing irradiance levels. Stimulus irradiance was incremented in 0.3 log unit steps. The ERG a-wave from ASP-treated retina was used to estimate the photoresponse of cones; the ERG b-wave from S-treated retina was used to estimate the light-evoked response of the output of cones; and the ON response of CAP from S-treated retina was used to estimate the light-evoked response of the optic nerve. Note that individual waveforms were vertically displaced for clarity of presentation. Horizontal thick lines indicate the time and duration of the light stimulus.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672170&req=5

pone-0066216-g001: Waveforms for ERG of ASP-treated retina, and for ERG and CAP of saline-treated retina.(A) Waveforms of electroretinogram (ERG) of aspartate (ASP)-treated retina, (B) ERG of saline (S)-treated retina, and (C) compound action potential (CAP) of S-treated retina at increasing irradiance levels. Stimulus irradiance was incremented in 0.3 log unit steps. The ERG a-wave from ASP-treated retina was used to estimate the photoresponse of cones; the ERG b-wave from S-treated retina was used to estimate the light-evoked response of the output of cones; and the ON response of CAP from S-treated retina was used to estimate the light-evoked response of the optic nerve. Note that individual waveforms were vertically displaced for clarity of presentation. Horizontal thick lines indicate the time and duration of the light stimulus.
Mentions: Spectral sensitivity was measured at different processing stages in the retina of rainbow trout. Sensitivity of the photoresponse of cones was estimated from the ERG a-wave of retina treated with aspartate (ASP) in saline (Ringer's solution); the sensitivity of the output of cones was estimated from the ERG b-wave of saline-treated retina; and the sensitivity of the optic nerve was estimated from the ON response of the compound action potential (CAP) of the optic nerve, projecting from saline-treated retina. See Figure 1 for ERG waveforms recorded from ASP-treated and saline-treated retina, as well as for CAP waveforms recorded from the optic nerve projecting from saline-treated retina.

Bottom Line: Color vision is most beneficial when the visual system is color constant and can correct the excitations of photoreceptors for differences in environmental irradiance.We found that the efficiency of color induction in the cone output and optic nerve decreased significantly with the inhibition of HC-cone feedback.Therefore, our findings suggest not only that color induction originates as a result of HC-cone feedback, but also that this effect of HC-cone feedback is further amplified at downstream retinal elements, possibly through feedback mechanisms at the inner plexiform layer.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Queen's University, Kingston, Ontario, Canada. shai_sabbah@brown.edu

ABSTRACT
Color vision is most beneficial when the visual system is color constant and can correct the excitations of photoreceptors for differences in environmental irradiance. A phenomenon related to color constancy is color induction, where the color of an object shifts away from the color of its surroundings. These two phenomena depend on chromatic spatial integration, which was suggested to originate at the feedback synapse from horizontal cells (HC) to cones. However, the exact retinal site was never determined. Using the electroretinogram and compound action potential recordings, we estimated the spectral sensitivity of the photoresponse of cones, the output of cones, and the optic nerve in rainbow trout. Recordings were performed before and following pharmacological inhibition of HC-cone feedback, and were repeated under two colored backgrounds to estimate the efficiency of color induction. No color induction could be detected in the photoresponse of cones. However, the efficiency of color induction in the cone output and optic nerve was substantial, with the efficiency in the optic nerve being significantly higher than in the cone output. We found that the efficiency of color induction in the cone output and optic nerve decreased significantly with the inhibition of HC-cone feedback. Therefore, our findings suggest not only that color induction originates as a result of HC-cone feedback, but also that this effect of HC-cone feedback is further amplified at downstream retinal elements, possibly through feedback mechanisms at the inner plexiform layer. This study provides evidence for an important role of HC-cone feedback in mediating color induction, and therefore, likely also in mediating color constancy.

Show MeSH