
When you split the brain, do you split the person? - Yossi_Frenkel
https://aeon.co/ideas/when-you-split-the-brain-do-you-split-the-person
======
otakucode
Dualism is wholly wrong. There is no mind-body split. Even speaking of 'the
brain' is just a rough convenience. Individual neurons stretch from that
tangled mass of them up in your skull all the way down your spine and to the
soles of your feet. Every nerve fiber extends from nearly every point in your
body right into your brain. Perception pours in from every point, and it is
all extremely important. Emotion, for instance, primarily arises from
biofeedback. Remove the feedback of feeling your 'expression' of emotion and
you will cease to be capable of 'feeling' that emotion.

Consciousness is not a 'thing', it is a property. Thus far we know of only one
sort of system that can hold the property (human beings in our environment)
although we do gain some information from observing humans of different
configurations (such as seeing that people with total facial paralysis
experience significant emotional dulling and substantial changes to their
subjective personal experience over time) that hints at what things are
important for different aspects. So far as we have evidence for, there is no
reason to think that you might be able to, for instance, simulate solely a
brain and have anything akin to consciousness. Just removing patterned sensory
input from a typical person via sensory deprivation quickly results in their
consciousness dissolving. So how a brain without a body and without an
environment to perceive might ever have a hope of consciousness I've no idea.

~~~
amelius
> Consciousness is not a 'thing', it is a property.

But if consciousness is only a property that doesn't influence the actual
physics, then how are we even able to talk about consciousness? Why would it
occur to physical beings that something like consciousness exists?

~~~
kazagistar
Not sure what that question means. An ocean wave is something that emerges
from the basic laws of physics, but its not actually a "thing", its just a
bunch of water exhibiting a property. The only difference between that and the
human mind (and properties of it like consciousness) is the level of
complexity and thus completeness of our ability to model it. The mind is a
wave in an ocean of brain.

~~~
amelius
Ok, so by "not a thing" you mean "abstraction", rather than something which
does not physically exist.

~~~
klank
It's a philosophical question about when does something begin to exist vs. it
is just an abstraction comprised of constituent parts.

[https://plato.stanford.edu/entries/material-
constitution](https://plato.stanford.edu/entries/material-constitution)

------
jpfed
Here's a thought experiment.

Say you had more than one RNN trained for the same task (say, generating
text). How would you couple them?

You could just, character by character, have each RNN generate its output on
its own, and then take a majority vote or do some weighted average to combine
the output, but otherwise let each RNN operate independently. But wouldn't it
be strange for those RNNs whose output was not ultimately selected to continue
processing along the same lines, uncorrected by what was actually selected?

Another possibility is to include a "ultimately selected" input to each RNN so
they can be privy to the group's decisions. Yes, your internal state said that
"e" should be selected, but the group selected "r"\- what will you do now?

Yet another possibility would be to perform "retroactive justification". Let
us say that one RNN (with an internal state S) selected "e", but the group
selected "r". Under retroactive justification, the state used for the next
character is a state (maybe the one closest to S) that would have instead
produced "r" as output.

Split brains are coupled by their shared access to the body and act within the
same environment. How do the hemispheres use that coupling?

~~~
otakucode
Unlike the metaphor you suggest, in the body decisions are not made by vote.
Each half the brain controls particular pieces, with the other not
participating. A closer metaphor would be separate RNN which each determine
one bit of the response, with the response being observed by each.

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AnIdiotOnTheNet
>How does a brain, consisting of many modules, create just one person?

The same way a population, consisting of many people, creates just one state?
The state is not the people and the people are not the state, yet both exist.

~~~
liberte82
But a state isn't conscious

~~~
AnIdiotOnTheNet
By what metric do you make that declaration? I submit that any empirical model
of consciousness applies equally to states as it does to human minds.

~~~
cscurmudgeon
If complexity is consciousness, then NYC's sewer system is conscious too.

~~~
dpark
No one said that complexity is consciousness.

~~~
cscurmudgeon
A lot do. E.g. Tononi's IIT.

~~~
dpark
Let me rephrase. No one _here_ said that complexity is consciousness. In
particular, AnIdiotOnTheNet, who you replied to, did not say that complexity
is consciousness.

Also, tangentially, New York's sewers aren't that complex compared to even a
rat's brain.

~~~
cscurmudgeon
Let me rephrase. No one here said that complexity is consciousness. In
particular, AnIdiotOnTheNet, who you replied to, did not say that complexity
is consciousness.

>Let me rephrase. No one here said that complexity is consciousness. In
particular, AnIdiotOnTheNet, who you replied to, did not say that complexity
is consciousness.

Not directly. If not complexity, is it a kind of computation or something
physical that makes neurons produce consciousness? Those positoins are more
tough to support.

> Also, tangentially, New York's sewers aren't that complex compared to even a
> rat's brain.

What is the magic measure and what is magic threshold using that measure?

What about a future city's sewer system that is complex enough?

~~~
dpark
I’m not sure what your intent is here. “Sewers are conscious” seemed to be a
reductio ad absurdum but now you seem to be arguing that complexity is
consciousness. Regardless, I haven’t proposed any mechanism for consciousness
to arise so I don’t have any “position to support” there.

------
have_faith
> But without the corpus callosum the hemispheres have virtually no means of
> exchanging information

They can communicate physically though. Each half of the brain can access the
eyes and control various parts of the body, they could make the body do things
that they could see/hear in order to act as a basic messaging channel. The
conscious part of the brain could be completely oblivious to these subtle
physical channels.

~~~
d33
Not sure what would be the evolutionary purpose of that. I doubt that many of
our ancestors survived brain split and managed to reproduce in order to pass
the genes, so having that feature would probably mean it's necessary for
something else... sounds like a long shot for me though.

~~~
AnIdiotOnTheNet
I think what is being suggested is not that it is a special function that only
occurs in the case of the corpus callosum being split, but that these other
communication channels are always operating regardless and the corpus callosum
is specialized channel for certain kinds of information. Speculating based on
the article, one would suspect that it allows for fast integration of visual
information, but that other integrations rely on other, probably slower,
channels.

~~~
bencollier49
The Corpus Callosum isn't the only interhemispheric commissure though, there
are several more. The anterior and posterior commissures, as well as the
Fornix etc.

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rwmj
Is he saying that the papers/experiments of Sperry (for which he won the Nobel
Prize) were not reproducible? They only tested two new patients. How rare are
split-brain patients? (I assume very rare indeed if they could only find two
subjects).

~~~
Roverlord
I imagine the neurosurgeons doing it to reduce epilepsy also want to preserve
as much connectivity as possible, so total severance of the tissue between the
hemispheres may be rarer in present population of splitbrain patients as their
technique improved?

------
johndoe489
Fascinating subject. Much more is address in Iain Mc Gilchrist's book

"The Master and his Emissary : the divided brain and the making of the western
world"

[http://iainmcgilchrist.com/](http://iainmcgilchrist.com/)

ps: put short, the book explains how pop psychology belief that left is maths
and right is arts (you get the idea), was wrong, and yet.. there is a
physiologically noticable difference as well as observable differences in how
each hemispheres processes reality. In short, each hemisphere attends to the
world with a different kind of attention, left is narrow and focused for what
we commonly see as intellectual acvitivites, left deals with a map of the
world. Right hemispheres takes the world as one whole, it's broad attention
required to survive in our environment, but it's also necessary for empathy,
etc. The book then tries to show how the over relianceo n our left hemisphere
in today's world has roots in the last few centuries, and that perhaps it is
not in our best interest. BOTH hemispheres are always needed, but we are
increasingly acting in the world from the left hemisphere (hence the book
title "the master and his emissary").

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bmn__
Video illustration of the previous experiments mentioned in the article:

[https://www.youtube.com/watch?v=wfYbgdo8e-8](https://www.youtube.com/watch?v=wfYbgdo8e-8)

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lucozade
> the current understanding seems to only deepen the mystery of consciousness

Not sure I understand that.

What they appear to have established is that, if you sever the direct
connection between the two brain halves, functions that required the direct
communication between the two halves is impaired.

I mean, it's interesting to note what those functions are and the severity of
the impairment. But there doesn't appear to be any effect on consciousness at
all; at least not in the article's description of the effects. Am I missing
something?

~~~
mfoy_
I think that's the point. The previous work referenced in the article seemed
to indicate something _much_ MUCH more profound.

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amelius
Conversely, when you combine two brains, do you "merge" the people?

~~~
anonymfus
[https://en.wikipedia.org/wiki/Krista_and_Tatiana_Hogan](https://en.wikipedia.org/wiki/Krista_and_Tatiana_Hogan)

~~~
emiliobumachar
Wow.

"There is evidence that the twins can see through each other's eyes due to
brain conjoining."

------
peter303
This is part of the philosophical problem of identity. Is there a non-physical
part of the mind? If you duplicate a body by cloning, matter relicator, or
exact uploading into a computer, do you have multiple persons or souls? (Star
Trek explored several variations) Does [any part of] the mind survive death?

------
legohead
The thing that has stuck with me is the career test that was given to someone
with a split brain, and one side wanted to be a racecar driver and the other
wanted to be something completely different. [1]

[1] [https://www.psychologytoday.com/blog/the-superhuman-
mind/201...](https://www.psychologytoday.com/blog/the-superhuman-
mind/201211/split-brains)

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SubiculumCode
There is a video about a split brain patient (somewhere), while they are
shopping. The left hand might put a box of cereal into the shopping cart, but
the right hand puts it right back on the shelf. I wish I cod find the video.

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rqs
> The brain is perhaps the most complex machine in the Universe.

That's when I found how useful a 'perhaps' can be. LOL.

------
Aardwolf
> The brain is perhaps the most complex machine in the Universe

Do you really know what's there in the entire universe?

~~~
jnty
No, hence "perhaps". The meaning and intent of the sentence is entirely clear
so I don't really see what good this sort of pedantry does.

