[PDF] Impulse encoding mechanisms of ganglion cells in the tiger salamander retina. | Semantic Scholar (2024)

FAQs

How are ganglion cells of the retina stimulated? ›

The classical receptive field of a ganglion cell is defined as the area of the retina where stimulation with a small spot of light produces a change in ganglion cell firing rate.

Three distinct morphological types of cat retinal ganglion cells have been identified and categorized as alpha, beta and gamma. Alpha ganglion cells have dendritic field diameters from 180 to 1000 mum; beta, about 25 to 300 mum; gamma, 180 to 800 mum, possibly more.

Ganglion cell axons terminate in brain visual centers, principally the lateral geniculate nucleus and the superior colliculus. Ganglion cell axons are directed to specific visual centers depending on the visual trigger features they encode. The optic nerve collects all the axons of the ganglion cells.

In the retina, RGCs synapse with bipolar and amacrine cells in the inner plexiform layer (IPL) to receive excitatory and inhibitory synaptic inputs respectively.

Ganglion cells show diverse responses to step changes of light (Figure 1(a)). Generally, responses can be divided into ON (activated by increases of light intensity), OFF (activated by decreases of light intensity), and ON–OFF (activated by both increases and decreases of light intensity).

Outside of the area centralis most retinal ganglion cells respond best to stimuli oriented radially, i.e., oriented parallel to the line connecting their receptive fields to the area centralis (Levick and Thibos, '82).

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. These axons form the optic nerve, optic chiasm, and optic tract.

Types of Retinal Ganglion Cells

Although there is some degree of consensus on major retinal ganglion cell types including midget RGCs, parasol RGCs and small bistratified RGCs, there has been some debate over classification of the remaining types.

These cells are a subset of retinal ganglion cells (RGCs) expressing the photopigment melanopsin that renders them sensitive to light.

General morphology.

Ganglion cells are larger on average than most preceding retinal interneurons and have large diameter axons capable of passing the electrical signal, in the form of transient spike trains, to the retinal recipient areas of the brain many millimeters or centimeters distant from the retina.

What is the distribution of ganglion cells in the human retina? ›

Retinal ganglion cells exhibit a topographic distribution across the retinal surface. They reach a peak density in a horizontally orientated elliptical ring surrounding the foveal center, though they are absent over the fovea itself (Standring, 2016; Ross and Pawlina, 2006).

Retinal ganglion cells process visual information that begins as light entering the eye and transmit it to the brain via their axons, which are long fibers that make up the optic nerve. There are over a million retinal ganglion cells in the human retina, and they allow you to see as they send the image to your brain.

Of the retina's nerve cells, only the retinal ganglion cells and few amacrine cells create action potentials. In the retinal ganglion cells there are two types of response, depending on the receptive field of the cell.

Retinal ganglion cells (RGC) have been described to react to light stimuli either by producing short bursts of spikes or by maintaining a longer, continuous train of action potentials.

It is the axons of the retinal ganglion cells (the 3° visual afferents) that exit the eye to form the optic nerve and deliver visual information to the lateral geniculate nucleus of the thalamus and to other diencephalic and midbrain structures.

Placing new RGCs into the diseased retina is only the first step in functional vision restoration. Once present, RGCs must elaborate dendrites within the inner plexiform layer (IPL) and generate synapses with bipolar and amacrine cells to receive visual information that will be processed and relayed to the brain.

Instead, the SCN-projecting retinal ganglion cells (RGCs) function as autonomous photoreceptors and exhibit light responses independent of rod- and cone-driven input.