Don’t underestimate your babies in the womb. They can see more than what you think usually about them.
According to a study, light-sensitive cells active in the retina even before the fetus can distinguish images. By the second trimester, long before a baby’s eyes can see images, they can detect light.
University of California, Berkeley, scientists have now found evidence that these simple cells actually talk to one another as part of an interconnected network that gives the retina more light sensitivity than once thought, and that may enhance the influence of light on behavior and brain development in unsuspected ways.
In the developing eye, perhaps 3% of ganglion cells — the cells in the retina that send messages through the optic nerve into the brain — are sensitive to light and, to date, researchers have found about six different subtypes that communicate with various places in the brain. Some talk to the suprachiasmatic nucleus to tune our internal clock to the day-night cycle. Others send signals to the area that makes our pupils constrict in bright light.
“Given the variety of these ganglion cells and that they project to many different parts of the brain, it makes me wonder whether they play a role in how the retina connects up to the brain,” said Marla Feller, a UC Berkeley professor of molecular and cell biology.
“Maybe not for visual circuits, but for non-vision behaviours. Not only the pupillary light reflex and circadian rhythms, but possibly explaining problems like light-induced migraines, or why light therapy works for depression.”
“We thought they (mouse pups and the human fetus) were blind at this point in development,” said Feller, the Paul Licht Distinguished Professor in Biological Sciences and a member of UC Berkeley’s Helen Wills Neuroscience Institute.