Any ideas how your eyes identify something coming to your way unexpectedly and avoid you from getting hit, or prevent something like accident from happening? Now the scientists at Washington University School of Medicine in St. Louis have identified eye’s motion sensors responsible for that rapid reaction after being studied on mice.
They have identified specific cell types that form a neural circuit in the retina at the back of eye that carries signal from the eye’s photoreceptors to the brain’s visual cortex, which then get translated into an image, enabling the eye to detect movement.
“This ability to detect motion is key for animals, allowing them to detect the presence of predators,” said Daniel Kerschensteiner, MD, an assistant professor of ophthalmology and visual sciences.
“And we know that these same cells are found not only in mice but in rabbits, cats, primates and likely humans, too. The cells look similar in every species, and we would assume they function in a similar manner as well.”
The identified specific type of cell is known as an amacrine cell – a small nerve cell within the retina which is responsible for detecting motion.
These amacrine cells make certain that the brain does not get flooded with too much visual information, which could distort an image, by refraining the activity of others cells called ganglion cells or gangliocytes.
The researchers also showed that when there is motion in the visual field, a specific secondary type of amacrine cell excites ganglion cells, signaling the brain so it becomes aware that an object is in motion.
“There are many elements in the retinal circuitry that we haven’t figured out yet,” said Kerschensteiner.
“We know the signals from the rods and cones are transmitted to the retina — where the amacrine and ganglion cells are located — and that’s really where the ‘magic’ happens that allows us to see what we see. Unfortunately, we still have a very limited understanding of what most of the cells in the inner retina actually do.”
The researchers hope with the study of this type, they would be able to build artificial retinas for people who have suffered vision loss.