Stuart Trenholm1 and Gautam B. Awatramani2 1Assistant Professor, Montreal Neurological Institute, McGill University, Montreal, Canada: stuart.trenholm@mcgill.ca 2Associate Professor, Department of Biology, University of Victoria, Victoria, Canada: gautam@uvic.ca Abstract Gap junctions are recognized in the electron microscope as dense starchy areas of opposed membrane between two cells. Small tracer molecules such as Neurobiotin pass through the …
Continue reading “Myriad Roles for Gap Junctions in Retinal Circuits by Stuart Trenholm and Gautam B. Awatramani”
Ethan D. Cohen, Ph.D., Abstract Retina prostheses try to reactivate the residual circuitry in a blind patient’s retina to produce a synthetic form of usable vision. Using an array of stimulus electrodes or light-sensitive proteins, the neurons in the degenerate retinal network are activated to elicit a series of light percepts termed “phosphenes”. If …
Continue reading “Retinal Prostheses by Ethan D. Cohen”
Bryan William Jones, Robert E. Marc and Rebecca L. Pfeiffer 1. Introduction Retinal degeneration and remodeling encompasses a group of pathologies at the molecular, cellular and tissue levels that are initiated by inherited retinal diseases like retinitis pigmentosa (RP), genetic and environmental diseases like age-related macular degeneration (AMD) and other insults to the eye/retina …
Continue reading “Retinal Degeneration, Remodeling and Plasticity by Bryan William Jones, Robert E. Marc and Rebecca L. Pfeiffer”
1 Introduction “Nothing in biology makes sense except in the light of evolution” (1). Theodosius Dobzhansky’s insight is especially apposite in trying to comprehend the nature of our rod and cone photoreceptors, and the organization of our retina. Unless we understand how these cells and structures arose, through hundreds of millions of years of evolution, …
Continue reading “Part XIV: Evolution of Phototransduction, Vertebrate Photoreceptors and Retina by Trevor Lamb”
Ning Tian Introduction The neuronal information of the visual scene that is processed by the retina is conducted to the brain by a set of separate spatio-temporal synaptic pathways. The morphological basis for the formation of these parallel synaptic pathways is the laminar-specific structure of the retina, in which specific subtypes of retinal neurons …
Continue reading “Development of Retinal Ganglion Cell Dendritic Structure and Synaptic Connections by Ning Tian”
By Silke Haverkamp Glycine is a major inhibitory neurotransmitter in the mammalian central nervous system (CNS). Its receptors, the inhibitory glycine receptors (GlyRs), are ligand-gated chloride channels composed of ligand-binding α and β subunits (Betz and Laube, 2006; Lynch, 2009). In mature neurons, the activation of GlyRs allows for an influx of chloride ions …
Continue reading “Glycine Receptor Diversity in the Mammalian Retina by Silke Haverkamp”
Steve Fisher, Geoffrey P. Lewis, Kenneth A Linberg, Edward Barawid and Mark V. Verardo 1. Introduction. What is retinal detachment? The retina is firmly attached to the apical surface of the retinal pigmented epithelium, or RPE (see earlier retinal anatomy sections). When the retina is separated from its normal position apposed to the …
Continue reading “Cellular Remodeling in Mammalian Retina Induced by Retinal Detachment by Steve Fisher, Geoffrey P. Lewis, Kenneth A Linberg, Edward Barawid and Mark V. Verardo”
Ido Perlman 1. Historical view. As early as 1865 Holmgren found that a light stimulus could cause a change in the electrical potential of the amphibian eye. Shortly afterwards, similar findings were reported by Dewar from Scotland. He showed that light illumination through the pupil, which had previously been covered, caused a …
Continue reading “The Electroretinogram: ERG by Ido Perlman”
Josh Morgan and Rachel Wong 1. Introduction. Synaptic connections of the vertebrate retina are organized into distinct laminae (Figure 1). In the outer retina, photoreceptors contact horizontal cells and bipolar cells within a single lamina, the outer plexiform layer (OPL). Within the inner retina, synapses between retinal ganglion cells and their presynaptic partners, the …
Continue reading “Development of cell types and synaptic connections in the retina by Josh Morgan and Rachel Wong”
Victoria Connaughton 1. General overview of synaptic transmission. Cells communicate with each other electrically, through gap junctions, and chemically, using neurotransmitters. Chemical synaptic transmission allows nerve signals to be exchanged between cells which are electrically isolated from each other. The chemical messenger, or neurotransmitter, provides a way to send the signal across the extracellular space, …
Continue reading “Glutamate and glutamate receptors in the vertebrate retina by Victoria Connaughton”
Helga Kolb 1. Circuitry for cone signals. Cone photoreceptors are the sensors of bright light and different wavelengths of light in the retina. They are sensitive in photopic (bright light) conditions and come in several types according to the structure of the visual pigments or opsins in their outer segment regions. In dichromatic …
Continue reading “Cone Pathways through the Retina by Helga Kolb”
Ralph Nelson 1. Overview. Ganglion cells are the final output neurons of the vertebrate retina. Ganglion cells collect information about the visual world from bipolar cells and amacrine cells (retinal interneurons). This information is in the form of chemical messages sensed by receptors on the ganglion cell membrane. Transmembrane receptors, in turn, transform …
Continue reading “Ganglion Cell Physiology by Ralph Nelson”
Helga Kolb 1. Bipolar, amacrine and ganglion cells interact in the inner plexiform layer. The axonal endings of bipolar cells bring information from the outer plexiform layer (OPL) to the neuropil of the inner plexiform layer (IPL). Here bipolar cells talk to different varieties of functionally specialized amacrine cells and to dendrites of …
Continue reading “Inner Plexiform Layer by Helga Kolb”
Helga Kolb A certain degree of integration of the visual message goes on at the first synapse in the retina, in the outer plexiform layer. Here cone pedicles and rod spherules are synaptic upon various bipolar cell and horizontal cell types. In addition, as mentioned in the previous section, cone pedicles pass electrical messages …
Continue reading “Outer Plexiform Layer by Helga Kolb”
Helga Kolb Two or three types of cone photoreceptor and a single type of rod photoreceptor are present in the normal mammalian retina. Some non-mammalian retinas have even more cone types (see later). 1. Light microscopy and ultrastructure of rods and cones. In vertical sections of retina prepared for light microscopy with …
Continue reading “Photoreceptors by Helga Kolb”