Researchers have now discovered that the cells in the retina are developed and so sensitive as connected to the brain. These electrically connected cells are called light-sensitive cells before the fetus cells can distinguish images may play a larger role in the developing eye and brain than previously thought. Intrinsically photosensitive retinal ganglion cells seemingly help establish blood supply to the retina, circadian rhythms and the pupillary light reflex. Researchers have now discovered that these cells are electrically connected in a network that is able to detect light intensity, suggesting a bigger role in development.
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 behaviour 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 the 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 and senior author of a paper that appeared this month in the journal Current 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."