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 A. Pyramidal cell. A pyramidal cell (or pyramidal neuron, or projection neuron) is a multipolar Neuron located in the Hippocampus and Cerebral B. Small multipolar cell, in which the dendrites quickly divides into numerous branches. A multipolar neuron is a type of Neuron that possesses a single (usually long Axon and many Dendrites allowing for the integration of a great deal of information C. Small fusiform cell. The fusiform gyrus is part of the Temporal lobe. It is also known as the (discontinuous occipitotemporal gyrus. D and E. Ganglion cells |
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| Location | Varies by type |
| Function | Varies but often excitatory projection |
| Morphology | Varies |
A ganglion cell (more correctly, a retinal ganglion cell or RGC) is a type of neuron typically located near the inner surface of the retina of the eye that receives visual information from photoreceptors via two intermediate neuron types (bipolar cells and amacrine cells). A ganglion cell (more correctly a retinal ganglion cell or RGC) is a type of Neuron typically located near the inner surface of the Retina The term morphology in Biology refers to the outward appearance ( Shape, Structure, Colour, Pattern) of an Organism Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information The vertebrate retina is a light sensitive part inside the inner layer of the Eye. Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain Photoreceptor can refer to In anatomy/cell biology Photoreceptor cell: a photosensitive cell most commonly referring to a specialized type of neuron A bipolar cell is a type of Neuron which has two extensions Bipolar cells are specialized sensory neurons for the transmission of special senses Amacrine cells are Interneurons in the Retina. Amacrine cells are responsible for 70% of input to retinal ganglion cells Retinal ganglion cells collectively transmit visual information from the retina to several regions in the thalamus, hypothalamus, and mesencephalon, or midbrain. The thalamus (from Greek θάλαμος = room chamber, IPA= /ˈθæləməs/ is a pair and symmetric part of the brain The hypothalamus links the Nervous system to the Endocrine system via the Pituitary gland (hypophysis In biological anatomy the mesencephalon (or midbrain) comprises the Tectum (or corpora quadrigemini Tegmentum, the ventricular mesocoelia (or "iter" In biological anatomy the mesencephalon (or midbrain) comprises the Tectum (or corpora quadrigemini Tegmentum, the ventricular mesocoelia (or "iter" Retinal ganglion cells vary significantly in terms of their size, connections, and responses to visual stimulation but they all share the defining property of having a long axon that extends into the brain. An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell These axons form the optic nerve, optic chiasm, and optic tract. The optic nerve, also called cranial nerve II, is the Nerve that transmits visual information from the Retina to the Brain. The optic chiasm ( Greek χίασμα "crossing" from the Greek χλαζειν 'to mark with an X' after the Greek letter ' Χ ' chi) is the The optic tract is a part of the Visual system in the Brain. It is a continuation of the Optic nerve and runs from the Optic chiasm (where
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Function
There are about 1. 2 to 1. 5 million retinal ganglion cells in the human retina. With about 105 million photoreceptors per retina, on average each retinal ganglion cell receives inputs from about 100 rods and cones. Rod cells, or rods, are Photoreceptor cells in the Retina of the Eye that can function in less intense Light than can the other type Cone cells, or cones, are Photoreceptor cells in the Retina of the Eye which function best in relatively bright Light. However, these number vary greatly among individuals and as a function of retinal location. In the fovea (center of the retina), a single photoreceptor will communicate with as many as five ganglion cells. The fovea, also known as the fovea centralis, is a part of the Eye, located in the center of the Macula region of the Retina. In the extreme periphery (ends of the retina), a single ganglion cell will receive information from many thousands of photoreceptors.
Retinal ganglion cells spontaneously fire action potentials at a base rate while at rest. In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal Excitation of retinal ganglion cells results in an increased firing rate while inhibition results in a depressed rate of firing.
Ganglion cells also reside in the adrenal medulla. The adrenal medulla is part of the Adrenal gland. It is located at the center of the gland being surrounded by the Adrenal cortex. They are involved in the sympathetic nervous system's release of epinephrine and norepinephrine into the blood stream. The Sympathetic Nervous System ( SNS) is a branch of the Autonomic nervous system along with the Enteric nervous system and Parasympathetic nervous Norepinephrine ( INN) (abbreviated norepi or NE) or noradrenaline ( BAN) (abbreviated NA or NAd) is a Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells such as nutrients and oxygen—and transports Waste products
Types
Based on their projections and functions, there are at least five main classes of retinal ganglion cells:
- Midget (Parvocellular, or P pathway; A cells)
- Parasol (Magnocellular, or M pathway; B cells)
- Bistratified (Koniocellular, or K pathway)
- Other ganglion cells projecting to the superior colliculus for eye movements (saccades) [reference: Principles of Neural Science 4th Ed. The superior colliculus ( Latin, higher hill) is a paired structure that is part of the Brain 's tectal area. A saccade is a fast movement of an eye, head or other part of an animal's body or device Kandel et al. ]
- Photosensitive ganglion cells
Midget
Midget retinal ganglion cells project to the parvocellular layers of the lateral geniculate nucleus. The lateral geniculate nucleus ( LGN) of the Thalamus is a part of the Brain, which is the primary processor of visual information received from the These cells are known as midget retinal ganglion cells, based on the small sizes of their dendritic trees and cell bodies. Dendrites (from Greek δένδρον déndron, “tree” are the branched projections of a Neuron that act to conduct the electrochemical About 80% of RGCs are midget cells in the parvocellular pathway. The visual system is the part of the Nervous system which allows organisms to see. They receive inputs from relatively few rods and cones. They have slow conduction velocity, and respond to changes in color but respond only weakly to changes in contrast unless the change is great (Kandel et al. A nerve conduction study (NCS is a test commonly used to evaluate the function especially the ability of Electrical conduction, of the motor and Sensory nerves , 2000). They have simple center-surround receptive fields, where the center may be either ON or OFF to one of the cones while the surround is the opposite to another cone. The receptive field of a sensory Neuron is a region of space in which the presence of a stimulus will alter the firing of that neuron
Parasol
Parasol retinal ganglion cells project to the magnocellular layers of the lateral geniculate nucleus. These cells are known as parasol retinal ganglion cells, based on the large sizes of their dendritic trees and cell bodies. "Parasol" redirects here For other uses see Umbrella (disambiguation, Umbrella (song or Parasol (disambiguation About 10% of retinal ganglion cells are parasol cells in the magnocellular pathway. They receive inputs from relatively many rods and cones. They have fast conduction velocity, and can respond to low-contrast stimuli, but are not very sensitive to changes in color (Kandel et al. , 2000). They have much larger receptive fields which are nonetheless also center-surround. The receptive field of a sensory Neuron is a region of space in which the presence of a stimulus will alter the firing of that neuron
Bistratified
Bistratified retinal ganglion cells project to the koniocellular layers of the lateral geniculate nucleus. Bistratified retinal ganglion cells have been identified only relatively recently. Koniocellular means “cells as small as dust”; their small size made them hard to find. About 10% of retinal ganglion cells are bistratified cells in the koniocellular pathway. They receive inputs from intermediate numbers of rods and cones. They have moderate spatial resolution, moderate conduction velocity, and can respond to moderate-contrast stimuli. They may be involved in color vision. They have very large receptive fields that only have centers (no surrounds) and are always ON to the blue cone and OFF to both the red and green cone. The receptive field of a sensory Neuron is a region of space in which the presence of a stimulus will alter the firing of that neuron
Other retinal ganglion cells projecting to the LGN
Other retinal ganglion cells projecting to the LGN include cells making connections with the Edinger-Westphal nucleus (EW) for control of the pupillary light reflex and giant retinal ganglion cells. The Edinger-Westphal nucleus (also known as the accessory oculomotor nucleus) is the accessory parasympathetic Cranial nerve nucleus of the Oculomotor Giant retinal ganglion cells are Photosensitive ganglion cells with large dendritic trees discovered in the Human and Macaque Retina by Dacey
Photosensitive ganglion cell
Photosensitive ganglion cells contain their own photopigment, melanopsin, which makes them respond directly to light even in the absence of rods and cones. Photosensitive ganglion cells, or melanopsin-containing ganglion cells, are a recently discovered type of nerve cell in the Retina of the mammalian Photopigments are unstable pigments that undergo a chemical change Melanopsin is a Photopigment found in specialized Photosensitive ganglion cells of the Retina that are involved in the regulation of Circadian rhythms They project to the suprachiasmatic nucleus (SCN) via the retinohypothalamic tract for setting and maintaining circadian rhythms. The suprachiasmatic nucleus ( SCN) is a bilateral region of the brain located in the Hypothalamus, that is responsible for controlling endogenous Circadian rhythms The Retinohypothalamic tract (RHT is a photic input pathway involved in Circadian rhythms.