Scientist discovers new way to repair damaged nerves
theglobeandmail.com
theglobeandmail.com
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.
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?
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.
The implications of the research are awesome, but the way they go about doing it...
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.