Document Type
Article
Publication Date
2-1-2021
Publication Title
Journal of Comparative Neurology
Abstract
Vertebrate retinas contain circuits specialized to encode light level decrements. This information is transmitted to the brain by dimming-sensitive OFF retinal ganglion cells (OFF-RGCs) that respond to light decrements with increased firing. It is known that OFF-RGCs with distinct photosensitivity profiles form parallel visual channels to the vertebrate brain, yet how these channels are processed by first- and higher order brain areas has not been well characterized in any species. To address this question in the larval zebrafish visual system, we examined the visual response properties of a genetically identified population of tectal neurons with a defined axonal projection to a second-order visual area: id2b:gal4-positive torus longitudinalis projection neurons (TLPNs). TLPNs responded consistently to whole-field dimming stimuli and exhibited the strongest responses when dimming was preceded by low light levels. Functional characterization of OFF-RGC terminals in tectum revealed responses that varied in their photosensitivities: (a) low-sensitivity OFF-RGCs that selectively respond to large light decrements, (b) high-sensitivity OFF-RGCs that selectively encode small decrements, and (c) broad sensitivity OFF-RGCs that respond to a wide range of light decrements. Diverse photosensitivity profiles were also observed using pan-neuronal calcium imaging to identify dimming-responsive neurons in both tectum and torus longitudinalis. Together, these data support a model in which parallel OFF channels generated in the retina remain segregated across three stages of visual processing. Segregated OFF channels with different sensitivities may allow specific aspects of dimming-evoked behaviors to be modulated by ambient light levels.
Keywords
dimming, functional imaging, larval visual motor response, multiphoton, OFF pathway, RRID:ZFIN_ZDB-ALT-090116-2, RRID:ZFIN_ZDB-ALT-090715-16, RRID:ZFIN_ZDB-GENO-140811-5
Volume
529
Issue
3
First Page
539
Last Page
552
DOI
10.1002/cne.24964
ISSN
00219967
Recommended Citation
Robles, Estuardo; Fields, Nicholas P.; and Baier, Herwig, "The Zebrafish Visual System Transmits Dimming Information via Multiple Segregated Pathways" (2021). Neuroscience: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/nsc_facpubs/66
Comments
Archived as published. Open access article.