scholarly journals Bilateral visual projections exist in non-teleost bony fish and predate the emergence of tetrapods

Science ◽  
2021 ◽  
Vol 372 (6538) ◽  
pp. 150-156
Author(s):  
Robin J. Vigouroux ◽  
Karine Duroure ◽  
Juliette Vougny ◽  
Shahad Albadri ◽  
Peter Kozulin ◽  
...  

In most vertebrates, camera-style eyes contain retinal ganglion cell neurons that project to visual centers on both sides of the brain. However, in fish, ganglion cells were thought to innervate only the contralateral side, suggesting that bilateral visual projections appeared in tetrapods. Here we show that bilateral visual projections exist in non-teleost fishes and that the appearance of ipsilateral projections does not correlate with terrestrial transition or predatory behavior. We also report that the developmental program that specifies visual system laterality differs between fishes and mammals, as the Zic2 transcription factor, which specifies ipsilateral retinal ganglion cells in tetrapods, appears to be absent from fish ganglion cells. However, overexpression of human ZIC2 induces ipsilateral visual projections in zebrafish. Therefore, the existence of bilateral visual projections likely preceded the emergence of binocular vision in tetrapods.

2019 ◽  
Vol 20 (13) ◽  
pp. 3282 ◽  
Author(s):  
Verónica Murcia-Belmonte ◽  
Lynda Erskine

Retinal ganglion cells (RGCs) extend axons out of the retina to transmit visual information to the brain. These connections are established during development through the navigation of RGC axons along a relatively long, stereotypical pathway. RGC axons exit the eye at the optic disc and extend along the optic nerves to the ventral midline of the brain, where the two nerves meet to form the optic chiasm. In animals with binocular vision, the axons face a choice at the optic chiasm—to cross the midline and project to targets on the contralateral side of the brain, or avoid crossing the midline and project to ipsilateral brain targets. Ipsilaterally and contralaterally projecting RGCs originate in disparate regions of the retina that relate to the extent of binocular overlap in the visual field. In humans virtually all RGC axons originating in temporal retina project ipsilaterally, whereas in mice, ipsilaterally projecting RGCs are confined to the peripheral ventrotemporal retina. This review will discuss recent advances in our understanding of the mechanisms regulating specification of ipsilateral versus contralateral RGCs, and the differential guidance of their axons at the optic chiasm. Recent insights into the establishment of congruent topographic maps in both brain hemispheres also will be discussed.


2018 ◽  
Vol 115 (50) ◽  
pp. E11817-E11826 ◽  
Author(s):  
Nina Milosavljevic ◽  
Riccardo Storchi ◽  
Cyril G. Eleftheriou ◽  
Andrea Colins ◽  
Rasmus S. Petersen ◽  
...  

Information transfer in the brain relies upon energetically expensive spiking activity of neurons. Rates of information flow should therefore be carefully optimized, but mechanisms to control this parameter are poorly understood. We address this deficit in the visual system, where ambient light (irradiance) is predictive of the amount of information reaching the eye and ask whether a neural measure of irradiance can therefore be used to proactively control information flow along the optic nerve. We first show that firing rates for the retina’s output neurons [retinal ganglion cells (RGCs)] scale with irradiance and are positively correlated with rates of information and the gain of visual responses. Irradiance modulates firing in the absence of any other visual signal confirming that this is a genuine response to changing ambient light. Irradiance-driven changes in firing are observed across the population of RGCs (including in both ON and OFF units) but are disrupted in mice lacking melanopsin [the photopigment of irradiance-coding intrinsically photosensitive RGCs (ipRGCs)] and can be induced under steady light exposure by chemogenetic activation of ipRGCs. Artificially elevating firing by chemogenetic excitation of ipRGCs is sufficient to increase information flow by increasing the gain of visual responses, indicating that enhanced firing is a cause of increased information transfer at higher irradiance. Our results establish a retinal circuitry driving changes in RGC firing as an active response to alterations in ambient light to adjust the amount of visual information transmitted to the brain.


Science ◽  
2018 ◽  
Vol 360 (6396) ◽  
pp. 1447-1451 ◽  
Author(s):  
Guosong Hong ◽  
Tian-Ming Fu ◽  
Mu Qiao ◽  
Robert D. Viveros ◽  
Xiao Yang ◽  
...  

The retina, which processes visual information and sends it to the brain, is an excellent model for studying neural circuitry. It has been probed extensively ex vivo but has been refractory to chronic in vivo electrophysiology. We report a nonsurgical method to achieve chronically stable in vivo recordings from single retinal ganglion cells (RGCs) in awake mice. We developed a noncoaxial intravitreal injection scheme in which injected mesh electronics unrolls inside the eye and conformally coats the highly curved retina without compromising normal eye functions. The method allows 16-channel recordings from multiple types of RGCs with stable responses to visual stimuli for at least 2 weeks, and reveals circadian rhythms in RGC responses over multiple day/night cycles.


2005 ◽  
Vol 80 (5) ◽  
pp. 663-670 ◽  
Author(s):  
Hana Levkovitch-Verbin ◽  
Harry A. Quigley ◽  
Keith R.G. Martin ◽  
Noga Harizman ◽  
Danielle F. Valenta ◽  
...  

Author(s):  
Baptiste Coudrillier ◽  
Kristin M. Myers ◽  
Thao D. Nguyen

By 2010, 60 million people will have glaucoma, the second leading cause of blindness worldwide [1]. The disease is characterized by a progressive degeneration of the retinal ganglion cells (RGC), a type of neuron that transmits visual information to the brain. It is well know that elevated intraocular pressure (IOP) is a risk factor in the damage to the RGCs [3–5], but the relationship between the mechanical properties of the ocular connective tissue and how it affects cellular function is not well characterized. The cornea and the sclera are collage-rich structures that comprise the outer load-bearing shell of the eye. Their preferentially aligned collagen lamellae provide mechanical strength to resist ocular expansion. Previous uniaxial tension studies suggest that altered viscoelastic material properties of the eye wall play a role in glaucomatous damage [6].


Author(s):  
C. Ross Ethier ◽  
Richie Abel ◽  
E. A. Sander ◽  
John G. Flanagan ◽  
Michael Girard

Glaucoma describes a group of potentially blinding ocular disorders, afflicting c. 60 million people worldwide. Of these, c. 8 million are bilaterally blind, estimated to increase to 11 million by 2020. The central event in glaucoma is slow and irreversible damage of retinal ganglion cells, responsible for carrying visual information from the retina to the brain (Figure 1). Intraocular pressure (IOP) is a risk factor for glaucoma1–4, and significant, sustained IOP reduction is unequivocally beneficial in the clinical management of glaucoma patients2, 3, 5. Unfortunately, we do not understand how elevated IOP leads to the loss of retinal ganglion cells.


2017 ◽  
Vol 114 (20) ◽  
pp. E3974-E3983 ◽  
Author(s):  
Szilard Sajgo ◽  
Miruna Georgiana Ghinia ◽  
Matthew Brooks ◽  
Friedrich Kretschmer ◽  
Katherine Chuang ◽  
...  

Visual information is conveyed from the eye to the brain by distinct types of retinal ganglion cells (RGCs). It is largely unknown how RGCs acquire their defining morphological and physiological features and connect to upstream and downstream synaptic partners. The three Brn3/Pou4f transcription factors (TFs) participate in a combinatorial code for RGC type specification, but their exact molecular roles are still unclear. We use deep sequencing to define (i) transcriptomes of Brn3a- and/or Brn3b-positive RGCs, (ii) Brn3a- and/or Brn3b-dependent RGC transcripts, and (iii) transcriptomes of retinorecipient areas of the brain at developmental stages relevant for axon guidance, dendrite formation, and synaptogenesis. We reveal a combinatorial code of TFs, cell surface molecules, and determinants of neuronal morphology that is differentially expressed in specific RGC populations and selectively regulated by Brn3a and/or Brn3b. This comprehensive molecular code provides a basis for understanding neuronal cell type specification in RGCs.


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