

Scientist discovers new way to repair damaged nerves  - edw519
http://www.theglobeandmail.com/news/technology/science/scientist-discovers-new-way-to-repair-damaged-nerves/article1396395/

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jasongullickson
Very interesting, but makes me wonder, why would the body naturally suppress
this growth at a certain age and what possible side-effects could come about
if this were altered?

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dunstad
At a guess, I'd say it suppresses the growth to conserve energy, but that's
just speculation. Were that the case, it seems like side effects would be
minimal.

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ars
I'd say quite different. It suppresses the growth in order to develop a mature
brain. Adults with the brains of babies probably don't do well.

To use an analogy.

Think of a blank canvas. Now add tons of random colored paints everywhere.
That's a baby. Over time remove the paint that is not part of the desired
painting (painting in reverse if you will).

If you make a mistake - no problem, more paint is constantly being thrown on
the canvas.

Over time less and less new paint is being thrown on, and your desired
painting emerges. Eventually no more paint is thrown on, and you have the
adult brain.

This is not a perfect analogy obviously, but it's the general idea.

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dunstad
I like this better than what I came up with, but there are parts of it I still
don't understand. I'm reading it like this: the new paint represents the
growing neurons, and when the neurons grow that's increasing your potential
brainpower.

The article says that you learn by pruning connections. I get the idea that as
a baby you think anything is possible, and as life goes on you learn that
trees can only walk in fiction, and when you touch something hot you get
burned. That would be like removing paint.

But what I don't get is this: say you read an article about something you
didn't know before, doesn't your brain make new connections (synapses) between
neurons? How are those and neuron growth different, and how does the synapse
learning fit into the paint model? Or am I misunderstanding how synapses work?

~~~
ars
> and when the neurons grow that's increasing your potential brainpower

No, not exactly.

> I get the idea that as a baby you think anything is possible

Also, no.

> But what I don't get is this: say you read an article about something you
> didn't know before, doesn't your brain make new connections (synapses)
> between neurons? How are those and neuron growth different, and how does the
> synapse learning fit into the paint model? Or am I misunderstanding how
> synapses work?

Exactly.

The thing that is growing by pruning is the _ability_ to learn. NOT the
learning itself.

A babies brain is disorganized, and doesn't have thought like an adult brain.
Over time it learns how to learn, it learns about cause and effect. It learns
there is an external world, and that it can effect that world.

It learns that it can reason about that world - if I do this, this happens -
and I thought of it.

It's like having raw hardware, without software. A baby creates the software
on the fly.

Later in life it fills the memory of the program with information, but the
program itself is learned early.

And by program, a better term might be firmware, since a person can learn new
way to think later in life. It's the machinery of thinking itself that a baby
creates.

That's why the environment during infancy and childhood has such a massive
effect later in life. It's why babies in almost any situation will adapt and
mange.

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rw
"The next step is to see if this is enough to restore the vision of the blind
mice [..] Baby mice with the same injury to the optic nerve repair the damage
without intervention."

The implications of the research are awesome, but the way they go about doing
it...

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albertcardona
It is a know fact that very young babies can regrow the distal tips of fingers
when cut off by accident. Human babies lose this ability after a few months
into life.

Body parts regrow forever: the skin is redone every 30 days. The regrowth,
though, is not a separate process from self-renewal from wear and tear. Bones,
for instance, remake themselves to the last atom every 4 years, yet a broken
bone won't regain its original shape in a human adult.

So the question is a matter of restoring a pattern. Why that doesn't happen is
not understood. Some vertebrates can do it without much trouble--think
salamanders being able to regrow part of their brain and eye, beyond the well-
known limb and tail cases.

From an evolutionary perspective we can speculate that the formation of a scar
is a big deal: it enhances short-term survival, which is a prerequisite for
long-term survival (this is not something silly to say). Current medical
research is showing (and already applying) that preventing scars allows some
tissues to regrow normally, the nervous system included. Still a long way
until medicine can regenerate a lost limb in a human, but there's supporting
evidence towards its feasibility in the near future.

