Updated: Dec 18, 2018
A large amount of evidence has displayed altered brain structures in response to the acquisition of new skills or knowledge. These changes not only occur at the overall structural level but also the cellular level.
To firstly brief you, a neuron is a unit comprising of an axon and several dendrites, which commonly transmit signals via neurotransmitters, from the end of one neuron to the dendrite of the next, where they are received by receptor cells.
Neuroplasticity can work in many ways, one major one being Long Term Potentiation (LTP) , which results in an increase in the count of receptors on the other side of the neuron, consequently increasing the likelihood of the firing of that neural pathway.
On a larger structural level, in addition to such strengthening of the synapses, there are the formation of new synapses among previously unconnected neurons, or the modification of existing connections between synapses . Ultimately, this results in a changing in the functional hierarchy of the mind based on experience.
Another application of neuroplasticity is from recovery from injury, where another part of the brain may take over a lost function due to brain damage . Interestingly, I was just reading a book describing how such plasticity is possible due to the coherent, organised and repetitive structure of the brain - being build of ‘blocks’ of neurons rather than a mesh of randomly interconnected neurons. Thus, each element of the brain used for a particular function is simply that section optimised for that particular action. This explains why other parts of the brain can take over lost control (due to their similarities in structure), but can never be quite as proficient (due to lack of optimisation, and difficulty to achieve such optimisation while having to manage other functions as well) .
A third form of ‘plasticity’, connected to the above point, involves the letting go or elimination of unpracticed functions, however this is primarily a feature among adolescents . If a particular memory or behavior is not recalled over time, the strength of the synaptic connection slowly dies in similar manners as explained above, resulting in loss of such ability.
Hence, yes, the brain is mouldable, but the extent of plasticity differs with age and various other factors, upon which research is still being conducted currently.