The eye is an organ that's easy to access, and biologists have been able to study it in detail. Light is sensed by special cells that are photoreceptors, and the information they collect is converted into nerve signals that are sent to the brain. We know a lot about how vision happens. But scientists have just discovered a new type of cell in the mammalian retina. The cell is a type of neuron, and the researchers called it a Campana cell because of its shape - the cell is shaped like a hand bell, which is sometimes called a campina. These cells are part of the complex system of circuitry that enables organisms to sense and react to their environments.
Campana cells seem to be a kind of intermediary, transmitting signals from what is seen by rod and cone photoreceptors, which sense light, on to other cells. Campana cells were found to have some things in common with retinal bipolar cells; they can both receive input from photoreceptors and relay information to retinal ganglion cells. More work will be needed to decipher their exact functions.
“Based on its morphology, physiology, and genetic properties, this cell doesn’t fit into the five classes of retinal neurons first identified more than 100 years ago,” said research team leader Ning Tian, PhD of the University of Utah. “We propose they might belong to a new retinal neuron class by themselves.”
In this study, which was reported in the Proceedings of the National Academy of Sciences, the researchrs showed that once Campana cells are stimulated, they stay active for an unusually long time. For example, a 10 millisecond light flash caused an activation that lasted for as long as 30 seconds.
“In the brain, persistent firing cells are believed to be involved in memory and learning,” said Tian. “Since Campana cells have a similar behavior, we theorize they could play a role in prompting a temporal memory of a recent stimulation.”
In the video, a Campana cell sits at the center. Other retinal cell types can also be seen; a bipolar cell is on the left and amacrine cells are seen on the right, both of which have some similarities with the Campana cell. The structure of the Campana cell is a kind of hybrid of the other two cell types.
Sources: University of Utah, Proceedings of the National Academy of Sciences
