Intelligent Design Mind Neuroscience

Michael Egnor’s thought experiment on partial brain transplants

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You might, Egnor thinks, end up seeing double out of an eye a thousand miles away. If you don’t agree, what do you think would happen?

… let’s assume a science fiction scenario — a thought experiment — in which there is an exchange. Jack gets Mary’s right eye/hemisphere and Mary gets Jack’s right eye/hemisphere. Both parties, who live on different parts of the planet, survive. For simplicity, we will focus on Jack’s right eye/hemisphere, which is now literally inside Mary’s head.

Jack’s right eye/hemisphere is surgically connected to Mary’s blood vessels, etc., so it remains alive. But it’s no longer connected with Jack’s body. It also can’t connect with Mary’s body because central nervous system tissue doesn’t regrow when cut. As a result, Jack’s right eye/hemisphere wouldn’t communicate via neurons with either Jack’s body or Mary’s.

That doesn’t necessarily mean that Jack’s right eye/hemisphere would do nothing. What if it simply does what it is capable of doing — mediating Jack’s visual perception from his right eye?

Jack would see out of his left eye/hemisphere. But he might also see something out of the transplanted right eye in Mary’s skull, even if he and Mary are thousands of miles apart. He would have something like double vision — two superimposed scenes, a thousand miles separated.

But how is this possible, even in a thought experiment? How does the right eye/hemisphere communicate with Jack? By what medium?

We tend to assume that there must be a medium of communication both between our eyes and our whole brain in order to see. But people who have had split brain surgery see quite well even though their hemispheres have been separated (thus there is no direct connection). If the eyes (and hemispheres) are separated by 4000 miles, would the principle be any different? On this view, we see where our eyes are, not matter how far they are apart.

Michael Egnor, “What if only part — not all — of your brain were transplanted?” at Mind Matters News

Our senses don’t actually work quite the way we think.

Note: Posting here a comment under News in the combox, for clarification, in response to a commenter:

“AaronS1978 at 1, it’s a thought experiment. Briefly, hearts pump blood and kidneys process urine. Unless you are getting distress signals, you don’t even know about it – because they are not sensory organs. They’re there to do a job, not to inform you about it.

The question is, if sensory organs were transplanted, whose would the sensations – if any – be? Dr. Egnor’s point is that it isn’t self-evident that there must be a specific kind of connection for sensation – split brain surgery demonstrates that, in his view. So, he asks, what would really happen in an experiment (that we hope will never be done)?”

Dr. Frankenstein has agreed to stay on a few more minutes to take your calls.

See also: Can cryogenics (freezing at death) preserve memories or consciousness? The question cryogenics of the connectome raises is, can we freeze and then recover consciousness itself as opposed to simply saving imprints of a person’s memories? Dr. Frankenstein is now taking your calls.

You may also wish to read: Are human brain transplants even possible? What would be the outcome if one person received transplants from the brains of others? If it’s not possible, there may be a good reason why not. If tiny bits of the brains from all the people in my neighborhood were transplanted into my brain, would there be a neighborhood in my skull? (Michael Egnor)

and

Researchers: our conscious visual perception lies outside our visual cortex. They concluded that the end step of perceiving where objects are occurs in the frontal lobes, a finding they describe as “radical”

6 Replies to “Michael Egnor’s thought experiment on partial brain transplants

  1. 1
    AaronS1978 says:

    So I have a few areas of contention here and I don’t agree with him on this

    Here’s why and I hope you hear me out

    1. This would be evidence we are just our brain

    2. If the soul is immutable, this could honestly be proof that it’s most certainly not has it can be separated

    3. When it comes to split brain patients and communication in the brain, you still have other nerves and connections that could in theory compensate for the disconnection. One such nerve is the claustrum. It could help but not fully solve the issue.

    4. This brings us back to the original problem with the head transplant of which you might as well say the soul and the brain are one same

    5. Now if the brain was a receiver then you might be right. However if I took the old tubes out of my tv while watching the Simpons and put them in a new tv in someone else’s home would the tv tubes still be on the simpons? Probably not

    Honestly if the soul is immortal and immutable it wouldn’t matter the parts you swap. It’s still the soul only with these new pieces

    I can’t see it binging remotely possibly that type of communication either

    Even split brains can still establish the slightest amount of communication between hemispheres

    Furthermore more when Dr. Egnor has performed such surgeries like removing sections of the brain, would his patients not have experience bizarre out of body side effects from the removed section of brain?

    Would the patients still have experienced those parts of their brains dying?

    I understand the brain for the most part can’t feel, however there is still data and processing going on in that section before it dies which could still be communicated to the soul if he was right.

  2. 2
    AaronS1978 says:

    Ugh this actually kind of upsets me and makes me doubt my perspective

  3. 3
  4. 4
    polistra says:

    Inside the head there’s always a total “holographic” connection via waves, which are probably at least as important as the electrochemical axon-to-synapse connections. The waves tend to entrain neurons to make new electrochemical connections. If the transplanted section can sync with the existing section, new growth of synapses MIGHT happen. I don’t know if the sync would be possible; there might be unique ‘grace notes’ in each resonance that cause an immune response. The existing brain might say “this isn’t my kind of music” and try to cancel it in a literal counter-wave way.

  5. 5
    News says:

    AaronS1978 at 1, it’s a thought experiment. Briefly, hearts pump blood and kidneys process urine. Unless you are getting distress signals, you don’t even know about it – because they are not sensory organs. They’re there to do a job, not to inform you about it.

    The question is, if sensory organs were transplanted, whose would the sensations – if any – be? Dr. Egnor’s point is that it isn’t self-evident that there must be a specific kind of connection for sensation – split brain surgery demonstrates that, in his view. So, he asks, what would really happen in an experiment that we hope will never be done?

  6. 6
    AaronS1978 says:

    @ 5
    I understand that, my concern, at least as how I read it is that you would have effective remote vision. Which I can see how that would work, no matter which view of the soul you have. Maybe the soul might experience both but there is no way for the body to know or record that

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