The human brain is pretty special, because it has this feature called plasticity.  Imagine the brain is gooey like play-dough.  As things change in our environment we can mould and reshape our brain to suit!  What we know about young brains is that they are extra gooey, and they can change based on two principles:
  1. Experience expected plasticity
  2. Experience dependent plasticity

Experience expectant plasticity

Now this one is really cool, and helps the human race to evolve to take advantage of changing environments.  Our genetics give our neurons a stencil or template on how they should probably connect up together after birth.  But our genes don’t have the final say!  After a human baby is born it fine tunes all of its connections based on the environmental conditions that it experiences and moulds its brain connections to take the best advantage of conditions.  To make sure that the brain succeeds in this it actually produces way more connections than it needs in each area, so it can then remove anything that is not needed later.

So, you can imagine brain areas like a hedge!  Say you moved into a dangerous neighbourhood and thought having a hedge shaped like a lion in your front garden would be the best way to scare away danger and thrive in your new environment.  What you would do is first grow a great big tall hedge, much larger than you need.  Then once it is grown you would start to shape and sculpt it to look more and more like the perfect lion that you need.  Prune a few leaves here and there, chop out a branch and reshape some areas.  This is what our brain is capable of!
hedge

Our babies need to explore and be exposed to lots of different things in order to join up connections in their brain.  Their brain then locates the BEST connections to help them in their environment and strengthens these while pruning away the less necessary connections.

Experience dependent plasticity

We can also mould our brains by using learning and memory.   That is, the brain changes itself as it learns information and stores some of the information in connections that we know as our ‘memory’. 

The first 3 years

The few years of your child’ s life involve a huge amount of making connections in the brain (synaptogenesis) but also a huge amount of getting rid of connections too (pruning)!  Connections that are repeated are strengthened, but those that aren’t repeated fade away.