June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Inhibition differentially tunes responses of direction selective retinal ganglion cells near the threshold of vision.
Author Affiliations & Notes
  • Suva Roy
    Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States
  • Xiaoyang Yao
    Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States
  • Jay Rathinavelu
    Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States
  • Greg Field
    Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States
    Ophthalmology, Jules Stein Eye Institute, Los Angeles, California, United States
  • Footnotes
    Commercial Relationships   Suva Roy None; Xiaoyang Yao None; Jay Rathinavelu None; Greg Field None
  • Footnotes
    Support  R01 EY-024567
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 2873. doi:
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    • Get Citation

      Suva Roy, Xiaoyang Yao, Jay Rathinavelu, Greg Field; Inhibition differentially tunes responses of direction selective retinal ganglion cells near the threshold of vision.. Invest. Ophthalmol. Vis. Sci. 2023;64(8):2873.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Detecting movement reliably under dim light conditions is critical for rodents to navigate their environment. Direction selective ganglion cells (DSGCs) in the retina encode information about movements across a broad range of light levels and relay this information to the brain. Previous work has shown that adaptation to low, rod-activating light levels, differentially tunes responses of ON-OFF DSGCs (ooDSGCs), such that superior direction preferring ooDSGCs exhibit broad tuning while ooDSGCs preferring other directions exhibit narrow tuning. Here, we sought to identify other functional asymmetries between the populations of ooDSGCs.

Methods : We used multielectrode array to measure spiking responses of hundreds of retinal ganglion cells in ex vivo retina. Retinas from wild-type mice (C57BL/6J) and conditional knockout mice with Cx36 mediated gap-junctions eliminated specifically in superior ooDSGCs (FACx), were used for experiments. Sparse white noise, dim flashes and moving grating visual stimuli at different light levels were presented, and spiking responses were measured under control condition and condition where GABA receptors were pharmacologically inhibited. Spike sorting was performed using custom written JAVA script.

Results : We found that the absolute sensitivity of superior ooDSGCs is tenfold higher than other ooDSGC subtypes. The higher sensitivity could be explained partly by a larger receptive field size and a difference in GABA mediated inhibition, between superior and non-superior ooDSGCs. Blocking GABA-ergic inhibition largely eliminated the difference in the threshold responses across ooDSGC subtypes. Using conditional knockout mice, we found that gap junction coupling did not significantly contribute to the absolute sensitivity difference between the ooDSGC subtypes. GABA-ergic inhibition was also found to mask the OFF responses of ooDSGCs under scotopic conditions.

Conclusions : This study reveals a functional asymmetry between different types of ON-OFF direction selective retinal ganglion cells (ooDSGCs), near the absolute threshold of vision. This asymmetry arises primarily because of different amounts of GABA mediated inhibition on superior versus non-superior ooDSGC subtypes.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

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