They are the rarest of the rarest of the rare. Tatiana and Krista are not just conjoined, but they are craniopagus, sharing a skull and also a bridge between each girl’s thalamus, a part of the brain that processes and relays sensory information to other parts of the brain. Or perhaps in this case, to both brains. There is evidence that they can see through each other’s eyes and perhaps share each other’s unspoken thoughts. And if that proves true, it will be the rarest thing of all. They will be unique in the world.
They have been drawing international attention, both public and scientific, since before their birth. Dr. Douglas Cochrane, a neurosurgeon at Children’s Hospital, is part of the team that has been watching over them since they were in the womb. Last year he conducted tests in which one twin looked at an object while he measured the brain activity in the other. “Their brains are recording signals from the other twin’s visual field,” he cautiously concluded. “One might be seeing what the other one is seeing.”
Adding to the conundrum, of course, are their linked brains, and the mysterious hints of what passes between them. The family regularly sees evidence of it. The way their heads are joined, they have markedly different fields of view. One child will look at a toy or a cup. The other can reach across and grab it, even though her own eyes couldn’t possibly see its location. “They share thoughts, too,” says Louise. “Nobody will be saying anything,” adds Simms, “and Tati will just pipe up and say, ‘Stop that!’ And she’ll smack her sister.” While their verbal development is delayed, it continues to get better. Their sentences are two or three words at most so far, and their enunciation is at first difficult to understand. Both the family, and researchers, anxiously await the children’s explanation for what they are experiencing.