>>18With Physics
[1].
Neuron pathways that aren't used "shrink", forming less and less connections over time, being activated less, consuming less resources, and eventually they are entirely relocated.
The brain also performs synaptic pruning
[2] from the time you are born until after puberty, to select the most efficient configuration that will require minimal GC.
[1]
http://arxiv.org/abs/quant-ph/0502072[2]
https://en.wikipedia.org/wiki/Synaptic_pruning