The term ‘ganglion cell’ usually refers to ganglion cells of the retina. Retinal ganglion cells receive visual information from photoreceptors in the retina and transmit nerve impulses to the visual cortex of the brain via the optic nerve.
What Are Ganglion Cells?
Ganglion cells are cells of the ganglion, which is a collection of nerve cells in the peripheral nervous system. However, the term ‘ganglion cell’ is usually used to refer to retinal ganglion cells (RGCs), which are found in the retina of the eye.
Location of Ganglion Cells
The term ‘ganglion cell’ may be used to refer to any type of cell found in the ganglion. The ganglion is any group of neurons in the peripheral nervous system (PNS). A group of neurons in the central nervous system (CNS) is called a nucleus.
Usually, when people say ‘ganglion cell’ they are referring to cells of the ganglion layer in the retina of the eye. These are also known as retinal ganglion cells (RGCs), and their key function is to transmit visual information to the visual cortex of the brain.
Structure of the Retina
The human retina contains over a million RGCs, which are located near the inner surface (or ganglion cell layer) of the retina. They form synapses with bipolar and amacrine cells in the inner plexiform layer (IPL) of the retina. Bipolar cells are interneurons, and also from synapses with photoreceptor cells called rods and cones.
Photoreceptors are specialized neurons that convert light signals into nerve impulses. Rods are the photoreceptors that allow us to see in the dark. They contain a photosensitive pigment and can detect shapes and movement in very low light. However, they are not sensitive to color, which is why it is hard to perceive color in a dim environment.
Cones are not as sensitive to light, but they are better at detecting color than rods. Cones work best in bright conditions and are activated by either red, blue, or green light. When light strikes a cone, it transmits a signal through the bipolar cells, to the RGCs and into the brain, where it is processed and interpreted as color.
Function of Retinal Ganglion Cells
The function of the RGCs is to transmit visual information collected by photoreceptors in the retina to the brain. When photoreceptors in the eye are stimulated by light, they send a signal to the bipolar cells which, in turn, pass it to the retinal ganglion cells. The axons of the RBCs form the optic nerve, which connects the retina to the visual cortex of the brain.
The optic nerve leaves the back of the eye through an opening called the optic disc, and transmits nerve impulses to the brain, where they are processed and interpreted as images.