We have a great deal more control over the age-related decline of the brain than was once thought - "use it or lose it", and the ability to affect change through challenging the mind. Yet it remains the case that new biotechnology and medicine will be required to get to where we want to be, a world without the risk of dementia, fuzzy memory, and slow cognition. Still, the plasticity of the aging brain is encouraging: "There is growing evidence that, beyond what was previously believed, the adult human brain is remarkably malleable and capable of new feats - even in the last decades of life. In fact, new experiences can trigger major physical changes in the brain within just a few days, and certain conditions can accelerate this physical, chemical and functional remodeling of the brain. ... We used to think that the brain was completely formed by development and its basic structure didn't change much in adults, but as research went on we discovered that wasn't true, at least in the cerebral cortex. We now know that an underlying portion of the brain called the thalamus, which feeds the cortex information from our senses, is also remarkably plastic. ... There is no evidence that there is any part of the adult brain that is not plastic. But studies indicate that some aspects of musical training, such as the ability to perceive temporal patterns, require the brain to be trained during early developmental periods when its primed for certain types of stimuli. For other aspects of musical development, such as the ability to perceive and repeat a sequence of tones, it's irrelevant whether you've had that experience and training early in life. ... The brain is plastic for life. The fundamental thing that determines how much [persons with brain disorders] will improve is the level of their initial impairment, but not their age."