Removing a side of the brain, can the patient still be conscious?

[revv]

I was wondering if there is anyone in the world that has had a side of there brain completely or partially removed and still be considered conscious? And if so is there a difference removing the left or right side of the brain? Like if you remove the left part of the brain are they still conscious? Or if you remove the right side?

 

[Ryan_m_b]

It’s rare but complete removal of one half of the brain is a medical procedure. There are (understandably) complications from it, but less than one would think:
https://en.m.wikipedia.org/wiki/Hemispherectomy

 

[revv]

Hm... it seems like some of them lead normal lives even after the operation if I read this correctly, so they are still conscious even if the left part is completely removed or right part? Is that right? If so that is really weird... consciousness still exist even if they remove one or the other side?

 

[jim mcnamara]

Yes. Consciousness is usually retained. And afterwards many epileptic patients are able to think more clearly, and not have a lot of the other problems associated with severe epilepsy. Obviously hemispherectomy is a serious operation so it is considered as a last resort.

-- that is what the link tells you minus the medical terminology - somewhat faster to get a hold of.

 

[revv]

Isn't that remarkable? I mean this brings up another question, how much of the brain can you take out until you aren't conscious anymore? Or is there a part where consciousness is located? I will do some more research on this but curious as to what you guys also think!

 

[revv]

Well I guess we already know where consciousness is "located" in the claustrum apparently, but now that I read into it consciousness doesn't seem that special, I mean according to the definition of it it is just self awareness and that doesn't seem like that big of a deal unless I am missing something. I guess what I find interesting is that you are still somewhat yourself even tho you are missing half of your brain or parts of it.

 

[BillTre]

Consciousness is not easy to define.
There has been much discussion about what is consciousness, how it is defined, how it might be identified in lower animals or computers.
How do we even know it even exists in people (either pre- or post-operation)?
That is, what is the test for this?

Just talking to them and coming to a decision reminds me of a low grade Turing test.

 

[Roddy]

Well what if someone removed all the gray matter or pink matter in a brain (I get it’d probably be death but still since this article is asking about removing parts from a brain)

 

[hyunxu]

Well what if someone removed all the gray matter or pink matter in a brain (I get it’d probably be death but still since this article is asking about removing parts from a brain)

https://en.m.wikipedia.org/wiki/Grey_matter

The respective function will not happen. Still each and every neuron found in brain is important. More over non-myelinated or non- medullated or grey neurons are present in grey matter of cerebrum.

 

[Bandersnatch]

I remember reading about two very interesting (and unrelated) cases of people with significant brain loss:
https://www.nature.com/news/2007/070716/full/news070716-15.html
https://en.wikipedia.org/wiki/Robert_Lawrence_(British_Army_officer)
Remarkably, both seem to have managed to lead normal lives. The hydrocephalus sufferer is a civil worker and a father of two. The veteran managed to charm an aristocrat and write a book.

 

[.Scott]

Well I guess we already know where consciousness is "located" in the claustrum apparently, but now that I read into it consciousness doesn't seem that special, I mean according to the definition of it it is just self awareness and that doesn't seem like that big of a deal unless I am missing something. I guess what I find interesting is that you are still somewhat yourself even tho you are missing half of your brain or parts of it.

This article looks at the function of the claustrum:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569501/
It seems tied to the sensory system at too basic a level to be the "seat of consciousness".

 

[.Scott]

Consciousness is not easy to define.
There has been much discussion about what is consciousness, how it is defined, how it might be identified in lower animals or computers.
How do we even know it even exists in people (either pre- or post-operation)?
That is, what is the test for this?

Just talking to them and coming to a decision reminds me of a low grade Turing test.

Short of a definition, we can identify some of its characteristics. First: when I am conscious, I am always conscious of something - information. Second: the something that I am conscious of would require many bits to encode. Third: when I or someone else reports they are conscious, they are presumably being earnest - so the conscious mechanism can have an effect on behavior.
You can judge for yourself whether this i consistent with your experience.

Moving on to neurology, we know that it seems to persist even when large parts of the brain have been damaged. And in split-brain situations, both hemispheres remain active and opinionated (although only one gets language). This suggests that it is not one location - but distributed. I would suggest there are many sites capable of creating the conscious experience, each with its specialty, but only one gets to record to memory and suggest intention.

 

[rootone]

I wonder how complex an organism has to be so that it can reasonably be asserted that it has consciousness.
It certainly is not a specific attribute of humans.
For example I see dogs waiting patiently outside a shop for their owner to emerge.
They are definitely conscious.

 

[.Scott]

I wonder how complex an organism has to be so that it can reasonably be asserted that it has consciousness.
It certainly is not a specific attribute of humans.
For example I see dogs waiting patiently outside a shop for their owner to emerge.
They are definitely conscious.

As a long-time software engineer, I would not connect "complexity" with "consciousness".
Humans (and likely all mammals) have consciousness mechanisms that serve some unclear Darwinian purpose. We also have lots of other mechanisms (memory, language center, visual processing, etc,) which give us rich channels of processed data to be conscious of.

When things get complicated to the point of apparent intractability, people often respond by describing the situation in summary terms but with the illusion that what they have is a complete picture. This is at its worse in trying to explain consciousness. It is common for people to explain consciousness as the natural result of complexity. I assure you that no system I have ever designed, no matter how complex, will ever experience a nanosecond of consciousness. Nor will the worlds communication systems, despite their complexity and inter-connectivity ever spontaneously awake.

But getting back to how the "complexity" of an organism relates to consciousness... Perhaps nothing has a more acute reputation for underscoring consciousness than pain - so let's use it as an example. The purpose of pain is to recruit the problem-solving parts of the brain to an urgent matter related to the preservation and repair of the body. You walk into a room after a good exercise and you immediately enjoy the A/C. But after 30 or 40 minutes, you feel cold. You are inspired to treat this as a problem. Perhaps, if others agree, you can turn the A/C down. Perhaps you can put on a sweater or use a blanket.

So the first thing the organism needs to feel pain is the ability to use the information. If it can never consciously solve such problems, there would be no purpose to the pain. Just about any mammal will meet that criteria.
In humans, pain takes on another aspect. Not only will it recruit your problem-solving resources - potentially to the exclusion of all other conscious activity - but it could drive you to grimace or cry. It's social! And being social, we are also impressed when others grimace or cry - potentially to the point of adopting it as our problem as well. Dogs are also social and will also whimper or cry - so presumably, they too are wired to be conscious of pain in others.
The point is even if an animal is conscious of pain (or other things), they won't necessarily share the same kind of conscious experience we do.

 

[jim mcnamara]

Thanks for the posts.

We are veering off-course here. Consciousness is an interesting subject, but as things stand now in the medical and biological communities it is largely a fringe discipline. Since everyone wants to do that, this is being moved to a non-science forum.