AHS: Can the brain have two separate consciounesses?

[tomgwyther]

Alien hand syndrome - Can the brain have two separate consiousnesses?

My original idea for this post was that it maybe possible to have two separate consciousnesses in one brain (One dominant and one sub-dominant.) from birth, thus giving rise to alien hand syndrome.

This lead me to consider how frustrating it would be to be the 'sub-dominant consciousness; to be self aware in a body you had little or no control over except for the manipulation of one limb.

 

Firstly, it is known to be possible to live a relatively normal life with only one cerebral hemisphere.

In cases of severe brain trauma (e.g. gunshot wound to the head) an entire hemisphere is removed along with half of the corpus callosum. The patient may well have difficulties with memory, sensory perception or motor control, but can otherwise go about their daily business.

Therefore, it is obvious to assume that one hemisphere of the brain is conscious and can operate independently of it's (possibly missing) other half.

 

In the case of alien hand syndrome, could it be that one hemisphere of the brain is actually a physical sub-dominant consciousness, literally with 'a mind of it's own.'?

Especially where the condition is brought about by damage to the corpus callosum and where the limb movements seem deliberate and purposeful.

“For example, one patient was observed putting a cigarette into her mouth with her intact, 'controlled' hand (her right, dominant hand), following which her alien, non-dominant, left hand came up to grasp the cigarette, pull the cigarette out of her mouth, and toss it away before it could be lit by the controlled, dominant, right hand. The patient then surmised that "I guess 'he' doesn't want me to smoke that cigarette" ”

What would it be like to be a sub-dominant consious? Aware of, but unable to interact with ones surroundings.

 

If it is true that each hemisphere can and does function as an individual independent consciousness, what does that mean for the rest of us?

That what we think of as one 'mind' is actually two 'minds' which are both capable of independent thought.

 

What are your thoughts on this? I'm not sure, I'm in two minds about it.

 

References:

http://my.clevelandclinic.org/services/Functional_Hemispherectomy/hic_Functional_Hemispherectomy.aspx

 

http://www.medterms.com/script/main/art.asp?articlekey=12655

 

http://www.damninteresting.com/?p=203

 

http://www.scielo.br/scielo.php?pid=S0004-282X2001000400007&script=sci_arttext

 

http://www.madsci.org/posts/archives/2000-12/976183734.Ns.r.html

[iNow]

Makes me think of this: http://en.wikipedia.org/wiki/Dissociative_identity_disorder

[tomgwyther]

It does sound similar, although D.I.D deals with more than two alter egos and is more psychological than physical.

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It also reminds me of a talk on TED, where a nueroscientist had a stroke and described her left and right hemispheres going on and off-line.

The description of the world she gave whilst her right hemisphere was working was very different to the one she gave when her left hemisphere was on-line.

 

Also, people with Bi-polar disorder tend to have a physically smaller callosum, maybe the occasional manias they encounter are due to a sub-dominant consiousness having it's way for a while.