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?
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.
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.
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?
> 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.
More speculation... Perhaps it is constricted by the size of the skull? At some point, the skull stops growing and larger neurons could put stress on the existing ones and cause damage.
"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...
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.
