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'Vegetative' patient speaks to scientists using his brainwaves

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Re: 'Vegetative' patient speaks to scientists using his brainwaves

#21

Post by ghotli »

There was a book written by a man with locked-in syndrome after a stroke. It made me want to write a living will.

"The entire book was written by Bauby blinking his left eyelid, which took ten months (four hours a day). A transcriber repeatedly recited a French language frequency-ordered alphabet (E, S, A, R, I, N, T, U, L, etc.), until Bauby blinked to choose the next letter. The book took about 200,000 blinks to write and an average word took approximately two minutes. The book also chronicles everyday events for a person with locked-in syndrome."

http://en.wikipedia.org/wiki/The_Diving_Bell_and_the_Butterf...

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#22

Post by RK »

mckilljoy wrote: post #17

This whole story is really very fascinating, although a few details seem a bit odd. For example, the patient didn't answer the last question because.. he fell asleep? I would imagine if I was trapped inside my body and suddenly given a mechanism to communicate, I would be too excited to fall asleep. Did they observe any signs of excitement that I would expect a person to feel in this situation? Increased heart rate o…

For example, the patient didn't answer the last question because.. he fell asleep? I would imagine if I was trapped inside my body and suddenly given a mechanism to communicate, I would be too excited to fall asleep.

They probably made that assumption because people fall asleep inside MRI's all of the time, especially during extremely long fMRI tests, when they try to isolate the senses (i.e. it's very dark, you wear earplugs and ear phones). Also, the brain damage might predispose someone to have a short attention span/wakeful periods.

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#23

Post by Sforlips »

mckilljoy wrote: post #17

This whole story is really very fascinating, although a few details seem a bit odd. For example, the patient didn't answer the last question because.. he fell asleep? I would imagine if I was trapped inside my body and suddenly given a mechanism to communicate, I would be too excited to fall asleep. Did they observe any signs of excitement that I would expect a person to feel in this situation? Increased heart rate o…

Actually, detecting brain activity in an MRI requires long aquisition times. Around 30 seconds per answer at least (which is the duration used in this study AFAIK). That means that a single "yes" (imagining you're playing tennis) or "no" (imagining you're walking in your house) requires 30 seconds of sustained attention.

This patient is obviously severely brain damaged.

If you've ever seen a person recovering from brain trauma, you'll know that their ability to focus is usually minimal. Answering questions for this patient may very well have been exhausting. This means that out of the other 22 patients in the study, some may be conscious but unable to cooperate long enough for the mnesic trace to be recorded.

Regarding other signs of activity, you can't detect random activity using fMRI. I haven't read this paper so I don't know the details (I'm only familiar with previous studies done by this team), but regarding heart rate, blod presure, etc, the brain damage may prevent it from occurring too.

Since he was only able to produce yes and no ansers using a contrieved process, he was of course unable to produce any other message.

He's definitely conscious.

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#24

Post by mckilljoy »

ghotli wrote: post #21

There was a book written by a man with locked-in syndrome after a stroke. It made me want to write a living will. "The entire book was written by Bauby blinking his left eyelid, which took ten months (four hours a day). A transcriber repeatedly recited a French language frequency-ordered alphabet (E, S, A, R, I, N, T, U, L, etc.), until Bauby blinked to choose the next letter. The book took about 200,000 blinks to wr…

So she went linearly through the whole alphabet until he found the letter he wanted? Sounds like somebody should have used a binary search! Hey-oooo!

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#25

Post by dandelany »

aarongough wrote: post #16
aaronblohowiak wrote: post #11

Earlier quoted context omitted.

The "trapped in a body" thing has a name and is well-researched: http://en.wikipedia.org/wiki/Locked-in_syndrome You should consider a living will if you are serious about avoiding this.

Good point on the living will... Up until now I have just made every person close to me promise to pull the plug if it ever came to a situation like this. I'll look into that some more...

I don't think a verbal promise like this would legally allow anyone to pull the plug, although I don't really know. Can any lawyers comment on this?

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#26

Post by mckilljoy »

pohl wrote: post #19
mckilljoy wrote: post #17

This whole story is really very fascinating, although a few details seem a bit odd. For example, the patient didn't answer the last question because.. he fell asleep? I would imagine if I was trapped inside my body and suddenly given a mechanism to communicate, I would be too excited to fall asleep. Did they observe any signs of excitement that I would expect a person to feel in this situation? Increased heart rate o…

Did the man try to convey his own message using the new-found communication mechanism? If I understand correctly, he was given the means to convey "yes" by imagining himself playing tennis. The concept of "no" was encoded by the absence of "yes". If he had wanted to send some message, like "tell my children I love them", or "I feel pain in my abdomen", how would he encode it?

He certainly can't send messages as complicated as that, but if I only had one bit to flip, I would be flipping it as much as possible to get someone's attention.

That said, he probably did the correct thing by simply answering their questions. That shows that "someone is home" better than flipping his bit randomly.

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#27

Post by bitwize »

pohl wrote: post #19
mckilljoy wrote: post #17

This whole story is really very fascinating, although a few details seem a bit odd. For example, the patient didn't answer the last question because.. he fell asleep? I would imagine if I was trapped inside my body and suddenly given a mechanism to communicate, I would be too excited to fall asleep. Did they observe any signs of excitement that I would expect a person to feel in this situation? Increased heart rate o…

Did the man try to convey his own message using the new-found communication mechanism? If I understand correctly, he was given the means to convey "yes" by imagining himself playing tennis. The concept of "no" was encoded by the absence of "yes". If he had wanted to send some message, like "tell my children I love them", or "I feel pain in my abdomen", how would he encode it?

"No" was encoded by imagining himself walking from room to room.

The absence of anything was recorded as "no answer".

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#28

Post by metamemetics »

rms wrote: post #15
aarongough wrote: post #6

If that patient is actually aware of his surroundings, then he has been trapped in a body with almost no sensory input for almost 6 years. Personally, that sounds like the worst hell imaginable. I've told everyone close to me that if I am injured badly they are to ask for 'no extreme measures' for this exact reason...

I think within a few months you would descend into a self-hallucinatory dreamworld -- you'd be insane, but I don't think it would be the worst hell imaginable. Not even close.

Hallucinations are caused by sensory-deprivation rather than motor parylization. For example, float tanks, also there are specially designed rooms that have as close to no background noise as possible, and people report hearing all kind of audio hallucinations such as bees, etc.

This test demonstrates he can at least hear sound. I'd imagine the effects would resemble senility from lack of engagement more.

Also, interesting side note, sleeping drugs such as Ambien in some cases allowed patients in coma to regain awareness and even hold CONVERSATION: http://www.guardian.co.uk/science/2006/sep/12/health.healtha...

Over stimulation by excitatory neurotransmitters is the primary cause of neuron death during stroke, the idea is that many neurons thought to be dead might have just shutdown to prevent from being overstimulated. And if baseline stimulation is reduced enough through what is normally sleeping medication, they might actually start to activate again.

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#29

Post by albertni »

mckilljoy wrote: post #24
ghotli wrote: post #21

There was a book written by a man with locked-in syndrome after a stroke. It made me want to write a living will. "The entire book was written by Bauby blinking his left eyelid, which took ten months (four hours a day). A transcriber repeatedly recited a French language frequency-ordered alphabet (E, S, A, R, I, N, T, U, L, etc.), until Bauby blinked to choose the next letter. The book took about 200,000 blinks to wr…

So she went linearly through the whole alphabet until he found the letter he wanted? Sounds like somebody should have used a binary search! Hey-oooo!

I wonder which would actually faster - binary search on the standard ordered alphabet or going linearly in order of letter frequency.

Even better - some hybrid algorithm that goes through the most common letters then goes into binary search for the remaining letters (many of which appear at approximately equal frequency)

Re: 'Vegetative' patient speaks to scientists using his brainwaves

#30

Post by jey »

mckilljoy wrote: post #24
ghotli wrote: post #21

There was a book written by a man with locked-in syndrome after a stroke. It made me want to write a living will. "The entire book was written by Bauby blinking his left eyelid, which took ten months (four hours a day). A transcriber repeatedly recited a French language frequency-ordered alphabet (E, S, A, R, I, N, T, U, L, etc.), until Bauby blinked to choose the next letter. The book took about 200,000 blinks to wr…

So she went linearly through the whole alphabet until he found the letter he wanted? Sounds like somebody should have used a binary search! Hey-oooo!

Frequency order is analogous to Huffman coding while still being easy enough for a human to use, so it's probably better than binary search.
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