Defining an adult - question

[marita_c]

This is for something that I’m writing:

Let’s say that a man (21+ y.o.) has ‘amnesia’: His language capabilities are intact, he can still win a game of Trivia, can operate a computer and play the piano – BUT his episodic memory is gone for good. He doesn’t know who he is, has absolutely no recollection of any previous experiences, events or people. 100% clean slate.

Many people say that it’s the experience the shapes the person – what you’ve been through throughout your life has made you into what you are.

According to this, once that man suffers said amnesia, he’s reduced, in many ways, to an infant. Would you consider that person to be an adult? Would you allow him to vote, drink alcohol, have sex? 

Comments

[nanfreak.livejournal.com]

Hmmm, whoever could you be speaking of? New story idea? *bounces* Don't let the squick stop the assporn, pls?

I would think that some suspension of disbelief is required, without memory, how could you speak, or walk, these are all learned skills. If he can't remember learning it, it's gone.

[marita-c.livejournal.com]

I'm afraid there's no assporn...

Of course some suspension of disbelief is required, in addition to some hardcore neuroscience, but not necessarily for the reason you're describing. I don't remember learning to walk and speak, yet I can do both. There are many things that I know, but can't recall the exact moment when I learned them.

[nanfreak.livejournal.com]

Gah, I knew that your science would thwart me... I know that with accident & stroke victims, they do need to relearn certain skills with substantial memory loss. Would memory loss equal brain damage? It seems to me that walking, talking, are long and complex learning processes that are cumulative learning experiences. So if one or two days are removed as an toddler, no likely effect but some formulative years...?

Would these be instinctive skills? How could one play Trivia without memories of learning the facts in school, etc? Not an infant then. How about emotional maturity then? Are learning and memory separate then?

[marita-c.livejournal.com]

see, I was going to spare you boring explanations, but now you're just asking for it, so here we go...

learning and memory are inseparable - whether you're learning to ride a bicycle, memorizing facts from a book or developing social skills - when you look at it in terms of neurons and synapses the processes are similar; All these "memories" or "skills" are encoded by modulating (changing the "strength" of) the connections between brain cells.

Your current ability to ride bicycle, which is well consolidated by now, is encoded separately from your (childhood?) memories of learning to ride a bicycle, and therefore it's possible to destroy one without affecting the other.

The 'suspension of disbelief' part comes into play if you want to turn this into a total and global effect - meaning, the different types of memories are all interconnected, i.e. you don't store all your skills in one area of the brain, all your book knowledge in another, and all your childhood memories elsewhere. Therefore, it's unlikely to end up with a person who's lost NONE of his skills and knowledge, but ALL of his past events and experiences.

When it comes to brain damage things get even more complicated - memories are encoded as refinement of synaptic connections. When there's brain damage you have a PERMANENT loss of cells and synapses. The biological parallel of the normal post-damage (e.g. stroke) "recovery" process is actually the surviving cells "rewiring" to compensate for lost cells and connections, and therefore you can usually get only limited recovery.

However (and here I'm giving away part of my story) even if you could regenerate 100% of the lost tissue, meaning, regrow the same number of brain cells with the same number of connections, the INFORMATION that used to be stored in these connections is still lost for good. BUT - while in the damaged brain your capacity to re-learn is diminished because of the cell loss, in the regenerated brain you have a pool of "blank" cells, or a "clean slate" that can be used to re-learn.

I'll be quiet now. :|