Are retinal ganglion cells myelinated?
Purpose.: In most mammalian species, retinal ganglion cell (RGC) axons are myelinated in the optic nerve, but remain nonmyelinated in the retinal nerve fiber layer and the most proximal (i.e., retina-near) region of the nerve.
What are retinal ganglion cells responsible for?
Retinal ganglion cells collectively transmit image-forming and non-image forming visual information from the retina in the form of action potential to several regions in the thalamus, hypothalamus, and mesencephalon, or midbrain.
What is the process of myelination in the brain?
Myelination is the process by which brain oligodendrocytes produce layers of myelin that wrap around the neuronal axons and act as a layer of insulation for the transmission of electric action potentials down the neuronal axon.
What is retinal myelination?
Myelinated retinal nerve fiber layers (MRNF) are retinal nerve fibers anterior to the lamina cribrosa that, unlike normal retinal nerve fibers, have a myelin sheath. Clinically, they appear to be gray-white well-demarcated patches with frayed borders on the anterior surface of the neurosensory retina.
Where do retinal ganglion cells synapse?
Retinal ganglion cells (RGCs) are the output neurons of the retina. In the retina, RGCs synapse with bipolar and amacrine cells in the inner plexiform layer (IPL) to receive excitatory and inhibitory synaptic inputs respectively.
How does myelination affect brain development?
As myelination progresses, more of the frontal lobes contribute to brain function, and this gradually increases the individual’s attention spans and improves the speed of processing information, both of which then improve with age.
What is myelination and what effect does it have?
Much like the insulation around the wires in electrical systems, glial cells form a membraneous sheath surrounding axons called myelin, thereby insulating the axon. This myelination, as it is called, can greatly increase the speed of signals transmitted between neurons (known as action potentials).
What does myelination of nerve Fibres cause?
In most vertebrates, the myelination of the optic nerve fibers commences at the optic disc (Perides et al., 1990). Due to an increase of light scattering, myelination of axons in the nerve fiber layer causes a decrease in the quality of image perception by the underlying photoreceptors.
What causes myelination of optic nerve?
Oligodendrocytes are responsible for the myelination of the ganglion cell axons, which normally begins at the lateral geniculate body and proceeds anteriorly to end at the lamina cribosa, which is thought to act as a barrier to the anterior migration of myelination into the retinal nerve fibres.
Are the axons of retinal ganglion cells myelinated?
In most mammals, the axons of retinal ganglion cells are not myelinated where they pass through the retina. However, the parts of axons that are beyond the retina, are myelinated.
Where do retinal ganglion cells enter the eye?
Axons of retinal ganglion cells conveying input from all areas of the retina converge at the optic disc, where they penetrate the choroid and sclera to form the optic nerve. Within the nerve fiber layer of the retina, ganglion cell axons are unmyelinated.
What is koniocellular retinal ganglion?
Koniocellular means “cells as small as dust”; their small size made them hard to find. About 10% of all retinal ganglion cells are bistratified cells, and these cells go through the koniocellular pathway. They receive inputs from intermediate numbers of rods and cones. They may be involved in color vision.
What is retinal ganglion cell atrophy?
It is a group of optic neuropathies characterized by the death of retinal ganglion cells (RGCs), leading to a specific deformation of the optic nerve head. Peripheral vision declines first in glaucoma, while central vision loss occurs much later.