Received: 12 August 2017 | Revised: 3 December 2017 | Accepted: 4 December 2017 DOI: 10.1002/cne.24377 The Journal of RESEARCH ARTICLE Comparative Neurology Distribution and diversity of intrinsically photosensitive retinal ganglion cells in tree shrew Elizabeth N. Johnson1,2 | Teleza Westbrook1 | Rod Shayesteh1 | Emily L. Chen1 | Joseph W. Schumacher3 | David Fitzpatrick3 | Greg D. Field1 1Neurobiology Department, Duke University School of Medicine, Durham, North Carolina Abstract 2Wharton Neuroscience Initiative, The Intrinsically photosensitive retinal ganglion cells (ipRGCs) mediate the pupillary light reflex, circa- Wharton School, University of Pennsylvania, dian entrainment, and may contribute to luminance and color perception. The diversity of ipRGCs Philadelphia, Pennsylvania varies from rodents to primates, suggesting differences in their contributions to retinal output. To 3 Max Planck Florida Institute for further understand the variability in their organization and diversity across species, we used immu- Neuroscience, Jupiter, Florida nohistochemical methods to examine ipRGCs in tree shrew (Tupaia belangeri). Tree shrews share Correspondence membership in the same clade, or evolutionary branch, as rodents and primates. They are highly Greg D. Field, Neurobiology Department, visual, diurnal animals with a cone-dominated retina and a geniculo-cortical organization resem- Duke University School of Medicine, bling that of primates. We identified cells with morphological similarities to M1 and M2 cells Durham, NC. described previously in rodents and primates. M1-like cells typically had somas in the ganglion cell Email:
[email protected] layer, with 23% displaced to the inner nuclear layer (INL). However, unlike M1 cells, they had bis- Funding information tratified dendritic fields ramifying in S1 and S5 that collectively tiled space.