Glia Regulate the Development, Function, and Plasticity of the Visual System From Retina to Cortex

Abstract

Visual experience is mediated through a relay of finely-tuned neural circuits extending from the retina, to retinorecipient nuclei in the midbrain and thalamus, to the cortex which work together to translate light information entering our eyes into a complex and dynamic spatio-temporal representation of the world. While the experience-dependent developmental refinement and mature function of neurons in each major stage of the vertebrate visual system have been extensively characterized, the contributions of the glial cells populating each region are comparatively understudied despite important findings demonstrating that they mediate crucial processes related to the development, function, and plasticity of the system. In this article we review the mechanisms for neuron-glia communication throughout the vertebrate visual system, as well as functional roles attributed to astrocytes and microglia in visual system development and processing. We will also discuss important aspects of glial function that remain unclear, integrating the knowns and unknowns about glia in the visual system to advance new hypotheses to guide future experimental work.

Visual Cortical Plasticity: Molecular Mechanisms as Revealed by Induction Paradigms in Rodents

“…The research conducted in neuron maturation in the vertebrate visual system was extensive in exploring experiencedependent development. However, the contribution of glial cells is much less understood [27]. Microglia activity is being studied for its involvement in this type of plasticity.…”

Retinal dysfunction in Huntington’s disease mouse models concurs with local gliosis and microglia activation

“…The retina is a highly organized tissue of the central nervous system (CNS) characterized by a high cellular diversity arranged in discrete layers. This organization determines the functionality of the retina, in which photoreceptor neurons (rods and cones) transduce light stimuli into the complex network of interneurons (amacrine, bipolar and horizontal cells) to finally converge into ganglion cells, which axons form the optic nerve 12 ; the retina also contains a specialized immune system with resident microglia and macroglia (astrocytes, Müller glia), which together with other nonneural type cells provide homeostatic and regulatory support to this network 13 . The retina can reproduce the disruption of key mechanisms that compromise cell function and viability of several neurodegenerative disorders, therefore the accessibility of this tissue to noninvasive techniques offers unique opportunities to infer the health status of inner regions of the CNS.…”

In vivo timelapse imaging and analysis of Golgi satellite organelle distribution and movement in the neural progenitor cells of the brain

“…Radial glial neural progenitor cells (NPCs) are dividing stem cells in the developing vertebrate brain. Also known as radial astrocytes, they have a periventricular-positioned cell body at the center of the brain, and a radial process (aka, basal process) that projects from the cell body and terminates in a flattened basal endfoot that interfaces with the blood brain barrier (1, 2). The tissue-spanning morphology of NPCs grows with brain development, reaching thousands of microns in some animals (3).…”