Two girls, one brain

No controlled studies have been done; because the girls are so young and because of the challenges involved in studying two conjoined heads, all the advanced imaging technology available has not yet been applied to their brains. Brain imaging is inscrutable enough that numerous neuroscientists, after seeing only one image of hundreds, were reluctant to confirm the specific neuro­anatomy that Cochrane described; but many were inclined to believe, based on that one image, that the brains were most likely connected by a live wire that could allow for some connection of a nature previously unknown. A mere glimpse of that attenuated line between the two brains reduced accomplished neurologists to sputtering incredulities. “OMG!!” Todd Feinberg, a professor of clinical psychiatry and neurology at Albert Einstein College of Medicine, wrote in an e-mail. “Absolutely fantastic. Unbelievable. Unprecedented as far as I know.” A neuroscientist in Kelowna, a city in British Columbia near Vernon, described their case as “ridiculously compelling.” Juliette Hukin, their pediatric neurologist at BC Children’s Hospital, who sees them about once a year, described their brain structure as “mind-blowing.”

An incomparable resource for neuroscientists interested in tracing neural pathways, in the malleability of the brain and in the construction of the self, Tatiana and Krista are also a study in the more expansive neural system of sociology: the feedback loop of how their family responds to difference, how the world outside the walls of their home responds to the family’s response and how the girls respond in turn. For now, for the most part, the girls are not treated as if they were, as one neuroscientist described them, “a new life form.” Although they rarely venture outside their home, they spend most days the way many preschoolers do, chasing after an uncle’s puppy or watching “Dora the Explorer” or testing their grandmother’s considerable patience as they play their private games at bedtime.

“Now I do it,” Tatiana said, reaching for the cup from which her sister was just drinking. She started to chug. Krista’s hand flew to her own stomach. “Whoa!” she said. The girls cracked up. Louise sighed. “Girls,” she said one more time. “It is time to settle down.”