Even Retina Cells Need Their Personal Space

Neurons don't exactly like crowds. Researchers have determined that nerve cells in the human eye actually have a mechanism in place to ensure that they don't go invading one another's "personal space" when forming, according to a recent study.

The study, published in the Proceedings of the National Academy of Sciences, details how researchers determined that a gene commonly known for regulating other parts of the body, and even involved pituitary tumor formation, may also be the driving factor that keeps nerve cells evenly spaced in the retina.

The retina has long been known as a home to "free-floating" neurons called cholinergic amacrine cells. Unlike other nerve cells in the body, the placement of these cells does not appear to vary from person to person. Instead, they always appear evenly spaced in a non-random pattern.

"Rather than being distributed as regular lattices of nerve cells, populations in the retina appear to abide by a simple rule, that of minimizing proximity to other cells of the same type," study author Patrick Keeley said in a statement. "We would like to understand how such populations create and maintain such spacing behavior."

According to the researchers, these retinal cells appear to position themselves much like strangers tend to evenly distance themselves in a crowded room, never invading one another's "personal space."

The reason for this is simple. If all neurons were not evenly spaced along the eye's retina, the organ's sensory functions would not be nearly as effective. Covering as much surface area as possible will send the proper signals for the brain to interpret.

Analyzing genetic factors that could influence retinal formation in mice, the researchers found that Pttg1, a genome previously not known to be involved in the retina, plays a significant role.

"Within this class of retinal neurons, [Pttg1] should be regulating the way in which cells integrate signals from their immediate neighbors, translating that information to position the cell farthest from those neighbors," Keeley explained.

Understanding neural networks in the most complex portions of the body is extremely important to science.

Earlier this month, stem cell researcher managed to successfully craft human retinal tissue in a lab. However, they explained that this retina was far from transplant ready - as many of the neural mechanisms involved in its formation were likely not fully functional. Understanding how these mechanisms work can help such research advance in the approaching years.