Parasol cell

Parasol cell is a type of retinal ganglion cell found in the mammalian retina. Named for their large, umbrella-like dendritic fields, parasol cells are one of the two primary types of retinal ganglion cells, along with midget cells. They play a crucial role in visual perception, particularly in the detection of motion and the perception of contrast.

Anatomy and Physiology

Parasol cells are characterized by their large dendritic fields, which are typically about twice the size of those of midget cells. They receive input from multiple bipolar cells and amacrine cells, and their axons form the majority of the optic nerve.

Parasol cells are further divided into two subtypes: on-parasol cells and off-parasol cells. On-parasol cells increase their firing rate in response to an increase in light intensity, while off-parasol cells increase their firing rate in response to a decrease in light intensity.

Function

Parasol cells are primarily responsible for detecting motion and contrast. They have a high sensitivity to changes in light intensity and are particularly active in low-light conditions. They also contribute to the perception of depth and spatial resolution.

Parasol cells are part of the magnocellular pathway, which carries information about motion and spatial relationships to the lateral geniculate nucleus (LGN) of the thalamus. From there, the information is relayed to the primary visual cortex.

Clinical Significance

Damage to parasol cells can result in a variety of visual impairments, including difficulties with motion perception and contrast sensitivity. They may also be affected in certain neurological conditions, such as glaucoma and Alzheimer's disease.

See Also

• Retinal ganglion cell
• Midget cell
• Magnocellular pathway
• Lateral geniculate nucleus
• Visual cortex