[extropy-chat] Singularity Drugs

[BillK]

On 4/16/06, Robert Bradbury wrote:
>
<snip>
> With respect to the learning rates of young people, you have to realize that
> young people have more neurons and many more synaptic connections than those
> who are older.  The rapid learning process involves the deletion of synapses
> and the death of neurons which are not "useful" ( i.e. those which are
> exercised at some level).  The learning one does as an adult is a much
> slower process that involves slow neuron replacement and tuning of the
> existing neural network (changing the relative strengths of various synaptic
> connections).  Think of it as the difference between casting a bronze statue
> (molten metal assuming a crystallized state where there was nothing
> previously) and the finishing and polishing of the statue after you take it
> out of the mold.  If you want to get back to the rapid state of "form"
> creation you have to remelt the bronze (regenerate an unpatterned neural
> network) and it isn't easy to do that without losing the pattern which is
> already present. [6]
>

I don't think this paragraph tells the whole story and thus may be misleading.

As Chomsky (1969) demonstrated, children between 5 and 10 years old
are still acquiring the structures of their first language.
Chomsky, N. (1969). The acquisition of syntax in children from 5 to 10.
Cambridge, MA: MIT Press.

Young children (up to 10 yrs) in a foreign country can quickly learn
to communicate with other children. But it is in a very simplified
'here and now' environment.

Current theory in educationalists is that age 11-13 is probably the
best age to learn a second language thoroughly.  But with proper
training and 'incentive' older ages are not much behind them.

Reference:
<http://www.pbs.org/wgbh/pages/frontline/shows/teenbrain/work/how.html>
Quote:
Now, imaging technologies let us visualize even more remarkable
changes in the brains of children and teens. Using MRI scans, we can
watch teenagers' brains change in miraculous patterns as they grow up.
We recently created the first maps of brain growth in individual
children and teens. To our surprise, an extraordinary wave of tissue
growth spread through the brain, from front to back, between the ages
of three and 15. Frontal brain circuits, which control attention, grew
fastest from ages three to six. Language systems, which are further
back in the brain, underwent a rapid growth spurt around the age of 11
to 15, and then drastically shut off in the early teen years.
End quote  --------------------


But there is a lot more involved in learning than just the raw capability.
You know how in many fields more skill and experience can easily
defeat untrained ability.


Also:
<http://www.rds-online.org.uk/pages/headline_detail.asp?i_ToolbarID=6&i_PageID=2114>
Quote:
Scientists once thought the adult brain was set in its ways. Using
mice, they've now discovered that adult neurons have a remarkable
ability to grow and change: some neurons can sprout new branches and
retract old ones. These findings add to a growing body of evidence
that older brains are still agile.

The researchers used mice that had a few neurons labelled with
fluorescent dye. They shaved off a small piece of a mouse's skull and
covered the opening with glass. Using this 'window', they took high
resolution pictures of the fluorescent neurons in the living brain.
They captured images of the same neurons over several weeks.

They found that dendrites (treelike extensions on neurons which
receive information from other brain cells) grew, shrank, and changed
over time – types of growth typical during development. Throughout
life we learn things so synapses must change in some way, but this
suggests that some changes may involve wholesale formation of new
synapses or loss of old ones.
End quote ------------------

The full report is at
<http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0040029>
Quote:
Here we show the first unambiguous evidence (to our knowledge) of
dendrite growth and remodeling in adult neurons. Over a period of
months, neurons could be seen extending and retracting existing
branches, and in rare cases adding new branch tips.
End quote ------------------


BillK