(CN) — How does a newborn mammal make visual sense of the world the first time it opens its eyes?
Essentially, mammals interpret clues in the womb to dream about the world they’ll be born into, according to a new Yale study published Thursday.
Led by Michael Crair, the William Ziegler III Professor of Neuroscience and professor of ophthalmology and visual science, a team of scientists have discovered waves of activity that emanate from the neonatal retina in unborn mice. Soon after birth, this activity is replaced by neural transmissions of visual stimuli to the brain, where information is encoded.
“At eye opening, mammals are capable of pretty sophisticated behavior,” said Crair.
Remarkably, mammals are born with a rudimentary capacity to perceive motion and navigate the world, the study found.
By imaging the brains of mice soon after birth, scientists found that these retinal waves mimic patterns of activity similar to what would occur if the mice were physically moving through their environment. Such activity prepares the mice to respond to their surroundings quicker than they would otherwise be capable of doing.
Such an ability is a matter of life and death, the study reasoned.
“This early dream-like activity makes evolutionary sense because it allows a mouse to anticipate what it will experience after opening its eyes, and be prepared to respond immediately to environmental threats,” Crair noted.
Researchers also investigated the neural circuitry generating retinal waves that mimic forward motion in unborn mice. By blocking the function of retina cells that release neurotransmitters, scientists could prevent the waves from flowing in the direction that mimics forward motion. Impeding these starburst amacrine cells hinders the mouse’s ability to respond to visual motion after birth.
In adult mice, these same cells are part of a more sophisticated motion detection circuit that allows them to react to environmental cues.
While limited to mice, the study’s larger implications provide insight into the development of a more prominent mammal — a human child. While newborn children cannot navigate their environment as quickly as mice, infants can detect objects and identify such motion as a finger moving across their field of vision. This suggests that their visual systems develop in the womb.
“These brain circuits are self-organized at birth and some of the early teaching is already done,” Crair said. “It’s like dreaming about what you are going to see before you even open your eyes.”
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