The Retina: A Window into the Brain

Abstract

In the course of evolution, animals have obtained the capacity to perceive and encode their environment via the development of sensory systems such as touch, olfaction, audition, and vision [...].

Figure 1

Snapshots of the habitat of different species along with their representative RGC density distribution across their retinal surfaces. (Left) Habitat of simians (jungle) and the RGC density distribution in the human retina. (Center) example of a typical habitat of the hawk (sky) and its retina RGC density distribution. (Right) example of a typical habitat of the mouse (ground) and its retina RGC density distribution. D, dorsal; N, nasal; T, temporal; V, ventral. Redrawn from [1].

Figure 2

The eye and the retinal mosaic. (A) A sagittal section of the eye (created with Biorender.com) and an Optical Coherence Tomography (OCT) scan of the central retina. The yellow arrow represents the path of the light rays entering the eye. (B) An H&E-stained transverse section of a human retina. Adapted from [15]. (C) Schematic organization of retinal cells from the retinal pigment epithelium to the nerve fiber layer. (D) Density of cones and rods throughout the retinal surface. Adapted from [16]. OCT, optical coherence tomography; R, rod; C, cone; H, horizontal cells; B, bipolar cells; A, amacrine cells; G, retinal ganglion cells; RPE, retinal pigment epithelium; PL, photoreceptor layer; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer; NFL, nerve fiber layer.

Figure 3

The vertical pathway of the retina. (A) Schematic organization of retinal cells. (B) Subtypes of photoreceptors (redrawn from von Greef, 1900). (C) Subtypes of bipolar cells. Redrawn from [26]. (D) Subtypes of retinal ganglion cells (RGCs) (redrawn from [38]). PL, photoreceptor layer; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer; NFL, nerve fiber layer; R, rod; C, cone; H, horizontal cells; B, bipolar cells; A, amacrine cells; G, RGCs; DSRGCs, direction selective retinal ganglion cells; J-RGCs, junctional adhesion molecule B-positive retinal ganglion cells; αRGCs, alpha RGCs; LED, local edge detector; iPRGCs, intrinsically photosensitive RGCs.

Figure 4

The retina horizontal pathway. (A) schematic organization of retinal cells. (B) Subtypes of horizontal cells. Redrawn from [60]. (C) Subtypes of narrow-field, medium-field and wide-field amacrine cells. Redrawn from [60,61]. PL, photoreceptor layer; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer; NFL, nerve fiber layer; R, rod; C, cone; H, horizontal cells; B, bipolar cells; A, amacrine cells; G, retinal ganglion cells.