Australia’s Aborigines or First People (that first we know about) have a rich mythology that includes the “Dreamtime”. It is their creation myth where spiritual beings shaped the world that we now know and inhabit, their wondrous deeds leaving in their wake the mountains and rivers, land and seas, forests, fish, animals and birds that make up our world.
According to new neuroscience research, babies of mice and people have our own dreamtime before we are born. In our mother’s womb our eye-brain system gets in practice for deciphering and responding to visual signals of a moving world, by dreaming it in advance. Or something like it.
Yale graduate students Xinxin Ge and Kathy Zhang, and their neuroscience professor Michael Crair, were curious as to how animals such as mice are able to react appropriately to visual signals very quickly after birth. They reasoned that when (for instance) a baby mouse’s eyes opened for the first time, it would be receiving visual information for the first time and the system would take a little time to learn how to make sense of visual sense; and nature’s fight for survival, how to react in the best way to stay alive.
Rodents like mice are born in quite a premature state, pink and hairless (a litter looks like a spoonful of baked beans) and with their eyes shut for a week or so. By some very clever imaging technology this team looked inside a new-born mouse’s brain, and they found “waves of activity that emanate from the neonatal retina in mice before their eyes ever open”.
“At eye opening, mammals are capable of pretty sophisticated behavior,” said Crair. “But how do the circuits form that allow us to perceive motion and navigate the world? It turns out we are born capable of many of these behaviors, at least in rudimentary form.”
Crair’s team explored the origins of these waves of activity. Imaging the brains of mice soon after birth but before their eyes opened, the Yale team found that these retinal waves flow in a pattern that mimics the activity that would occur if the animal were moving forward through the environment.
“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,” Michael Crair noted.
Here is the animated image of the retinal waves that the Yale team detected in the neonatal eyes-still-shut mice. They employed fluorescent calcium imaging to get these remarkable images of the baby mouse’s dreamtime:
Mice, of course, differ from humans in their ability to quickly navigate their environment soon after birth. However, human babies are also able to immediately detect objects and identify motion, such as a finger moving across their field of vision, suggesting that their visual system was also primed before birth.
“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.”
So as our babies dream in the womb, what dreams do they see? How does the eye-brain guess that the world – or mother – looks like? When they open their little eyes for the first time and see us looking back at them – it it deja-vu already?