Embryonic chicks can be made briefly conscious during the last twenty percent of their time in the egg, if you know how to wake them up. But why would we want to do that?
Above is a chick with an alert and awake brain. It's scrunched up because it's still in the egg, and will remain there for the remaining twenty percent of its development. Before this time, the chick isn't really awake or entirely asleep. Its neurological development, according to scientists at Universidad Carlos III in Madrid and McGill University, its brain patterns are analogous to someone under anesthesia or in a coma. Even then, researchers were surprised to find spontaneous movement of the body, although without any higher brain function.
Once eighty percent of its development was done, though, the higher functions in the brain kicked on, and the chick took on a kind of semi-waking and sleeping cycle, and the spontaneous movement stopped. The cycle wasn't totally in response to what was happening in the egg. The researchers played a series of sounds, some of which were meant to wake the chick up, while others were 'meaningless.'
So what has meaning to a chick? Chicken noises, of course. Making hen noises to chick, what the researchers referred to as 'chicken stimulus,' woke the chick up and got a neurological response. Meanwhile, white noise played to a chick didn't induce the same response. It seems that some instincts kick in, even before the chick is even hatched.
The researchers were excited to see the level of activity while the chick's brain was still being developed. They hope to apply what they learn to the responses of the brain in human fetal development, and even the understanding and treatment of human babies born very prematurely.
Image: Balaban et al. Current Biology