The Twins Who Share A Brain

November 5, 2010 10:54 AM

Tatiana and Krista Hogan are 4 year old twin girls who are joined at the head. Amazingly, their brains are interconnected and share the thalamus, the section of the brain that is responsible for relaying physical sensation and motor function to the cerebral cortex. As a result, it is believed that they can experience one another’s sensations, including seeing though each other's eyes.
posted by jpdoane (43 comments total)

Those of us lucky enough to be in the UK can watch the documentary on them through 4OD.
posted by brambory at 11:06 AM on November 5, 2010 [1 favorite]

Cue Daniel Dennett essay in 5...4...3...
posted by mister-o at 11:09 AM on November 5, 2010 [5 favorites]

Nah, I wanna read the Oliver Sacks essay.
posted by echo target at 11:11 AM on November 5, 2010 [11 favorites]

“When one gets in trouble and you try to discipline her, the other one kicks in and starts defending her sister,” says Simms. “I’ve just gotten to the point where if they don’t change their attitude when you talk to them the first time they both go into time out. How do you not?” she asks. “It’s just come down to . . . you can’t discipline one without disciplining the other. It’s just impossible.”

As the father of a four year old girl, I hesitated even to open the link.

But this comment (above) from the mother made me smile - they're just normal kids with normal parents who are finding a way to make a normal life. I am awed and inspired.
posted by three blind mice at 11:12 AM on November 5, 2010 [1 favorite]

You know, the more I think about it, I really want to read the Oliver Sacks essay. Get on a plane already, Ollie!
posted by echo target at 11:13 AM on November 5, 2010

That's just fascinating. I hope for the girls' sake that they make it.
posted by valkyryn at 11:18 AM on November 5, 2010

their brains are interconnected and share the thalamus, the section of the brain that is responsible for relaying physical sensation and motor function to the cerebral cortex

The thalamus deserves more credit than that. Think of information moving through the brain like water does through a fountain; it sprays up through the center and blooms outward to reach all parts of the cortex (the outermost layer of the brain), then trickles back inward where it is sprayed up and out again. In this metaphor, the thalamus is the fountain nozzle. This arrangement results in feedback loops, which are suspected to be essential components of consciousness. It's not just a relay—there is integration and processing going on.

If they truly do share a substantial thalamic bridge, they may in fact be closer to being a single person rather than two.
posted by dephlogisticated at 11:22 AM on November 5, 2010 [21 favorites]

WELL! This sure is interesting.
posted by josher71 at 11:23 AM on November 5, 2010

I hope they study neuroscience and use themselves to discover some really awesome stuff about how the brain functions.

"I'm not explaining this right. Put on your Hogan device so I can show you what I'm thinking."
posted by VTX at 11:24 AM on November 5, 2010 [6 favorites]

"I'm not explaining this right. Put on your Hogan device so I can show you what I'm thinking."

WATCHA GONNA DOOOO?
posted by lumensimus at 11:27 AM on November 5, 2010 [3 favorites]

Best double post on Metafilter I've ever seen.

There is something in my eye.
posted by chavenet at 11:30 AM on November 5, 2010 [1 favorite]

Amazing, the things people are doing with parallel processing these days.
posted by edguardo at 11:38 AM on November 5, 2010

In that picture of the twins, does the striped sweatshirt have a zipper or button in the back? I can't figure out how you'd get just one of them dressed in that.
posted by emelenjr at 11:40 AM on November 5, 2010

"I'm not explaining this right. Put on your Hogan device so I can show you what I'm thinking."

I think you mean "hold still while I get my point of view gun."
posted by jedicus at 11:41 AM on November 5, 2010

So they can both smell what The Rock is cookin?
posted by blue_beetle at 11:47 AM on November 5, 2010 [1 favorite]

I can't be the only one whose first thought was "Thank DOG they live in Canada!"

But then, I've been on the phone with insurance companies this afternoon. Anyway, amazing, amazing story. I hope these girls have long, happy lives together.
posted by sonika at 11:56 AM on November 5, 2010 [4 favorites]

I'm eager to see follow up stories as the kids get older and can start to explain what the subjective experience is like. If they even can. how do you explain the normal inside of your head and your perceptions?
posted by SaharaRose at 11:56 AM on November 5, 2010

“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.”
posted by dirtdirt at 12:02 PM on November 5, 2010 [6 favorites]

Fascinating. Thanks for sharing.
posted by ThePinkSuperhero at 12:40 PM on November 5, 2010

There's something really intriguing about the first picture in the first link, where you can see that the eyebrows on the sides of their faces that are closer to each other (the concave angle?) are arched, as if they're permanently sharing a joke with each other that the rest of the world wouldn't understand.
posted by Halloween Jack at 12:53 PM on November 5, 2010 [3 favorites]

“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.”

That is just fucking spooky. Does that mean that they can't keep secrets from each other?
posted by spicynuts at 1:00 PM on November 5, 2010

“They’re here for a reason,” she says, as you lace up your shoes and prepare to leave. “We just don’t know the reason yet.”

Short list of possibilities:

1) Some sort of god thought it would be fun/interesting/useful to create conjoined twins who share part of their brain.
2) The stars/fate determined it would be thus.
3) A fertilized human ovum almost split, but not completely, resulting in a rare case of conjoined twins due to purely random but natural causes.

As a trained theologian, I'm going with #3.
posted by Pater Aletheias at 1:18 PM on November 5, 2010 [25 favorites]

Great, now I can't finish my refried beans.

Do you want these, jpdoane?

DO YOU WANT THESE
posted by circular at 1:20 PM on November 5, 2010

“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.”

Actually, I think I did that with my (non-connected) siblings. What were they doing that bothered me? Existing.
posted by echo target at 1:23 PM on November 5, 2010 [20 favorites]

I love this. It poses so many questions about personhood, identity and consciousness. I hope that these two (?) can teach us much about ourselves, but at the same time, I hope they can live happy lives untrammeled by their extraordinary nature.
posted by Mental Wimp at 1:31 PM on November 5, 2010

Nah, I wanna read the Oliver Sacks essay.

The girl who mistook her sister for a hat?
posted by condour75 at 1:33 PM on November 5, 2010 [7 favorites]

“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.”

Yeah, if you think this requires telepathy, Louise, you must be an only child.
posted by eritain at 1:34 PM on November 5, 2010 [5 favorites]

s/Louise/Simms/;
s/bad reading skills/good ones/;
posted by eritain at 1:40 PM on November 5, 2010

What I wouldn't give for the chance to run some cognition experiments on them. Are they even a them? Perhaps they are actually better referred to as she? Where does one person end and the other begin, when sensation, perception and possibly even thought is shared?
posted by Sternmeyer at 1:52 PM on November 5, 2010

I hope they become writers. They could probably come up with awesome stories in the heads that can share visual input.
posted by dabitch at 1:56 PM on November 5, 2010

Slightly obscure question-- has anyone read Spider Robinson? Specifically, Lady Slings The Booze?

If yes-- A) I will love you forever
B) It's Arethusa. Only... more literal!

The rest of you, carry on.
posted by SaharaRose at 3:09 PM on November 5, 2010 [1 favorite]

Of course, nothing is assured. The state of their health can turn on a dime. Every day they defy the odds. So many odds. How many mothers would have done what Felicia Simms did, not terminating the pregnancy, knowing what she knew? How many families would have banded together, and stayed together, and grown stronger in a bond almost as fierce as that of the twins—ignoring, or at least absorbing, the financial hardships, judgmental stares and whispered disapprovals?
Their mother has come to accept each day with them as a gift and a little miracle; its purpose still unfolding. “They’re here for a reason,” she says, as you lace up your shoes and prepare to leave. “We just don’t know the reason yet.”

I know the focus is on the twins, but I don't like how this article is written. It's not wrong to abort. You're not a bad person for having an abortion even if you wanted just a healthy baby and the ultrasound or the tests showed a problem and you decided to abort. You're not especially courageous for seeing a risky pregnancy to term. They're lucky to live in Canada and have healthcare. But it's really unfair to say that this couple is "courageous" because they did not terminate the pregnancy or any of the other five pregnancies that they had. I personally think it's financially reckless and they are lucky to live in a country that makes it possible for them not to have to live in the street.

I also dislike this sentence:“No,” says Tatiana as though dealing with a mental defective. “Bounce it!”

Is this magazine a tabloid?
posted by anniecat at 3:12 PM on November 5, 2010 [7 favorites]

Oh man. I am taking a neuroanatomy course right now and I would KILL to see the MRI of their brain(s). So many questions! What's the corpus callosum like? If they've got one thalamus between them does it evenly project to (and recieve projections from) both sets of cortex or is one twin doing most of the cortical stuff for a given process and then sharing it back? They've definitely got two spines and brainstems, and presumably two cerebellums, so how in the world is one thalamus even resolving the sensorymotor chatter going on so that they can move at will independently!?

Wow.
posted by slow graffiti at 3:23 PM on November 5, 2010 [3 favorites]

Is this magazine a tabloid?

I really hate "[Thing] is the Canadian version of [American thing]," but Maclean's is sort of the Canadian Newsweek. Make of that what you will.
posted by Zozo at 3:33 PM on November 5, 2010 [1 favorite]

If you're interested in the life of conjoined twins, I highly recommend Lori Lansens' novel The Girls, whoch looks at a set of Canadian conjoined twins and is a wonderfully written, captivating book.
posted by DarlingBri at 3:37 PM on November 5, 2010

OK. That just blew my brain.
(And I only have one.)
posted by iamkimiam at 4:25 PM on November 5, 2010

I know the focus is on the twins, but I don't like how this article is written. It's not wrong to abort.

What. It didn't say anything about abortion being wrong, or that their mom was courageous.
posted by emeiji at 5:58 PM on November 5, 2010 [1 favorite]

This is incredible.

FWIW, I think there are certainly two people here, which is, I guess, why I think it's so incredible. Two people who share a brain. Biology is amazing.

I also hope they live full lives that involve writing books. If we are all really lucky, maybe that will lead to putting on a Hogan device.
posted by Leta at 6:58 PM on November 5, 2010

Dear Lord, the name of the series is "Stigmata." Ugh.
posted by bardic at 9:17 PM on November 5, 2010

I wonder what will happen when they get to school and have to start taking tests and exams...
posted by carmel at 7:27 AM on November 6, 2010

... they'll be able to look at each others responses.
posted by de at 11:28 AM on November 6, 2010

Surprised no one has mentioned the Hensel twins, conjoined at the chest. Different but comparable identity issues:

For tasks such as responding to e-mail, they type and respond as one, anticipating each other’s feelings with little verbal communication between them. In such cases as the latter, their choice of grammatical person is to use the first person singular out of habit when they agree, but when their responses do differ, they use their names in the third person singular.
posted by rdc at 12:56 PM on November 8, 2010

I may have mentioned this before, but I've seen the Hensel twins walking down the street in Minneapolis with several friends. I was walking with my wife to a play at the Guthrie and was absorbed in our conversations when I glanced over to my right and thought half-consciously, "This is a strange time of year for someone to be dressing up in a Halloween costume." It was only after a double take that I realized who they were.
posted by Mental Wimp at 2:33 PM on November 8, 2010