sinapses&weights

[Bruno Herencic]

How are those sinapse weights set in a human brain? I understand we can
simulate a simple neural net on a computer and change those weights, but how
did the nature set those weights? when? are they being changed over the
time... how? if a brain wants to remember something, memorize, or do
something, it must change those weights, doesn't it? this means input data
can have some inapct on those nets in the brain...?