" Altering connections in a way that strengthens the efficiency of a neuronal circuit over the long term was the first kind of neuroplasticity to be discovered. Plasticity must be a response to experience; after all, the only thing the brain can know and register about some perception is the pattern of neural activity it induces. This neural representation of the event somehow induces physical changes in the brain at the level of neurons and their synapses. These physical changes “allow the representation of the event to be stored and subsequently recalled,” says Tim Bliss of the National Institute for Medical Research in Mill Hill, England. In a very real sense, these physical changes are the memory. "

― Jeffrey M. Schwartz , The Mind and the Brain: Neuroplasticity and the Power of Mental Force