June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
In vivo and ex vivo characterization of macaque ganglion cells projecting to the superior colliculus
Author Affiliations & Notes
  • Kendall Kohout
    Center for Visual Science, University of Rochester, Rochester, New York, United States
  • Sara S Patterson
    Center for Visual Science, University of Rochester, Rochester, New York, United States
  • Amber Walker
    Center for Visual Science, University of Rochester, Rochester, New York, United States
  • Jennifer M. Strazzeri
    Center for Visual Science, University of Rochester, Rochester, New York, United States
    David & Ilene Flaum Eye Institute, University of Rochester, Rochester, New York, United States
  • David R Williams
    Center for Visual Science, University of Rochester, Rochester, New York, United States
    Institute of Optics, University of Rochester, Rochester, New York, United States
  • William Merigan
    Center for Visual Science, University of Rochester, Rochester, New York, United States
    David & Ilene Flaum Eye Institute, University of Rochester, Rochester, New York, United States
  • Footnotes
    Commercial Relationships   Kendall Kohout None; Sara Patterson University of Washington, Code P (Patent); Amber Walker None; Jennifer Strazzeri None; David Williams Warby Parker, Code F (Financial Support), Alcon, Code F (Financial Support), University of Rochester, Code P (Patent); William Merigan Alcon, Code F (Financial Support)
  • Footnotes
    Support  NIH Grant P30 EY001319, R01 EY021166, R01 EY031467, F32 EY032318, Research to Prevent Blindness
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 4573 – F0435. doi:
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    • Get Citation

      Kendall Kohout, Sara S Patterson, Amber Walker, Jennifer M. Strazzeri, David R Williams, William Merigan; In vivo and ex vivo characterization of macaque ganglion cells projecting to the superior colliculus. Invest. Ophthalmol. Vis. Sci. 2022;63(7):4573 – F0435.

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

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Abstract

Purpose : The macaque retina conveys visual information to the brain via ~20 anatomically distinct retinal ganglion cell (RGC) types. Yet only the most common LGN-projecting types have been characterized physiologically. Many of the remaining RGCs project to the superior colliculus (SC), an evolutionarily ancient region implicated in eye movements and, most recently, perceptual decision making. Here we catalog SC-projecting RGC types in the macaque retina and develop an approach to anatomically identify and physiologically characterize them in the living eye.

Methods : Injections of the retrograde tracer rhodamine dextran were aimed at the foveal SC in two macaques. Two stereotaxic-coordinate based injections were made in one macaque, and one MRI-guided injection was made in the second. Rhodamine expression was mapped with a fundus camera, then imaged in detail with adaptive optics scanning light ophthalmoscopy (AOSLO). The second macaque also expressed the genetically-encoded, calcium indicator GCaMP6s in the ganglion cell layer (Fig. 1). In the first macaque, post-mortem ex vivo imaging with a confocal microscope supplemented the in vivo imaging of rhodamine expression.

Results : Each injection labeled a sparse population of SC-projecting RGCs, consistent with earlier reports. We imaged the rhodamine-labeled RGCs in vivo with AOSLO, and some could be coaligned with GCaMP6s-expressing RGCs. The calcium responses of RGCs in rhodamine-labeled regions did not differ from areas without rhodamine expression. We traced the dendritic fields of 64 rhodamine-labeled RGCs that were imaged ex vivo with a confocal microscope, identifying parasol, smooth monostratified, large sparse, broad thorny and narrow thorny RGCs.

Conclusions : A complete account of the retinal input to the SC has been elusive since the rarity of many SC-projecting RGC types makes them difficult to target for physiological investigation. The anatomical approach developed here could address this gap in knowledge, laying the foundation for subsequent in vivo measurements of the response properties of these rare and understudied RGC types.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Fig. 1 Fundus images of A. rhodamine expression and B. GCaMP6s expression. Asterisk marks center of the fovea

Fig. 1 Fundus images of A. rhodamine expression and B. GCaMP6s expression. Asterisk marks center of the fovea

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