The twin cats example tries to exemplify the notion above such as that even sight (or probably other main senses as well) are heavily dependent on learning. In this case, it was proven that movement is essential for perceptual learning.
In order to develop concepts of reality (again, if such a thing actually exists out there) one uses very little information and when combined with stored information in memory as well as learning, then "some reality" is being built.
Once again, the big father of anatomy, Santiago Ramon Y Cajal, cannot be avoided!
It's the strenght or weaking of existing synaptic connections. The Hebb Hypothesis (1949):
This particular condition makes the synapse stronger. It says that you first activate a spike, in the pre-synaptic cell (with the electrode) - blue electrode). Then, with the red one, you activate a EPSP at the post-synaptic cell. Suddenly, after enough repetition, the synapse becomes stronger. This is called Long-Term Potentiation (LTP), the synapse is potentiated and becomes stronger in time (minutes/hours/days/lifetime...). If you do it in the reverse order of time, meaning that if you first activate the post-synaptic cell and then the pre-synaptic one, the synapse grows weaker and we have Long-Term Depression (LTD).
We refer to structural plasticity as the anatomical/morphological brain tissue changes that are correlated to learning. In 1967, Globus & Scheibel found that sensory experience affects dendritic spine variation (creation or deterioration) in rabbits.
Do new-born cells exist in the mammalian adult brains? This is called neurogenesis and the answer is yes, contrary to the common belief from the past (we can use cell-staining methods to track them).