Originally published in 2011.
Conjoined Irish Canadian twins, Krista and Tatiana Hogan, are making scientific history. The sisters from British Columbia share a mind.
From the very beginning doctors noticed something strange about the girls. When one was being pricked with a needle the other’s face would be a mirror image or her sister’s; wincing and bursting into tears. One pacifier in one of the baby’s mouths would sooth them both.
This is not to say that they are like many sets of twins who experiences similar feelings or emotions at the same time. These Irish Canadian twins are literally sharing the same consciousness, they are making scientific history.
Having observed the twins behavior, studied scans and examined their brain’s biology doctors believe that their brains are linked, from one thalmus to another. The thalmus is comparable to the switchboard of the brain; it filters sensory input and has long been thought to be the part of the brain which creates consciousness.
Krista and Tatiana are joined by the head, in medical terms this is known as craniopagus. They are one in 2.5 million babies and there was only a fraction of a chance that they would survive.
Douglas Cochrane of British Columbia Children’s Hospital, the twins’ neurosurgeon, describes their condition as their thalamus being linked by a bridge. He says that is the input that one of the twins receives crosses that bridge it is entirely possible that the sense crosses to the other twin’s brain. Their brains are connected by a live wire.
They have been described by one neuroscientist as “a new life form” but they like any other four-year-olds are treated like separate little girls who spend the day chasing their uncle’s puppy, watching “Dora the Explorer”, testing their grandmother’s patience and playing together in their room.
The twins were born, healthy at 34 weeks. The big decision was then on their parents, Felicia Simms and Brendan Hogan, whether to separate the girls. Their neurosurgeon, having consulted with various others, said it was too risky.
James T. Goodrich, director of pediatric neurosurgery for Children’s Hospital at Montefiore in the Bronx consulted on the case. He said “You’d have to have cut through too much normal tissue and split the thalami…It would have potentially been lethal.”
Now that the children are happy and healthy their family is not eager to have them tested and examined by the medical community in the pursuit of science. Doug McKay, their step-grandfather, explains “If one of them needs it for their health, by all means, they can do what they need to do…But I’ll be damned if you’re going to poke and prod and experiment on them.”
Cochrane says the family are “able to play the hand they’ve been dealt . . . and to recognize that these kids are growing and developing. And that they’re not that different from normal kids.”
When the twins were two-years-old Cochrane covered Krista’s eyes and flashed a strobe light in front of Tatiana. Their brain responses appeared to be the same. In a home environment the same thing appears to happen. The family told reporter that when one of the girls is watching TV, and the other’s head is tilted away, they still both laugh at the same time. Similarly the reporter for the New York Times speaks of tickling one of the girl’s feet and the other giggling loudly.
Another example is when their mother put a thermometer in Krista’s mouth and almost instantly Tatiana objects saying “not in the mouth”. Tatiana then curls her tongue as if the apparatus was in her mouth.
Their connection goes right down to their taste buds. For example Krista likes ketchup but Tatiana does not. They discovered this when Tatiana was trying to scrap the ketchup out of her mouth even though she had not eaten it.
Krista and Tatiana run, play, annoy their siblings but every now and then they do something that is surprising. For example in the company of the New York Times reporter they refer to themselves with certainty as “I”. They both simultaneously say “I have two pieces of paper” and repeat the phrase.
They never refer to themselves as “we” always as one person. Although ordinarily people have the ability to default to the idea of “self” and “I” these pair feel what the other feel. They are two people living as one and with the same sensory input. But this begs the question does it goes beyond sensory.
Their family believes that in some way the girls truly share a mind. They say the girls will often get up silently walk over to, for example, a sippy cup. Tatiana will pick it up and pass it directly to Krista who will drink.
* Originally published in 2011.