This is the most compelling book I have read all year. It delves into neuroplasticity—the brain's ability to change itself with experience—by exploring its origin, interviewing the brilliant minds who pushed the field forward, and digging into its applications in areas from love to stroke rehabilitation. I simply cannot stop talking about it to anyone who will listen. “Look!”, I now yell from the rooftops, “Look at what we are capable of”.

Until recently, the scientific community believed the adult brain to be unchanging and machine-like, with specific regions hardwired to perform specific functions, enshrined as the revered principle of localizationism. Once fully developed, there was believed to be no scope for reorganization. Brain damage was therefore believed to be permanent and any resulting loss of function irreversible. For example, if someone damaged the part of the brain that controlled the left side of the body (such as during a stroke), the damage was considered permanent and that person was relegated to a life without that function. Neuroplasticity, on the other hand, is the ability of the brain to reorganize itself, especially in response to learning or experience or following injury.

The book starts out with how Michael Merzenich made it his life's work to take the notion of neuroplasticity from an idea that was dismissed as fantastical hearsay by the scientific community to an accepted scientific principle. Through a series of ingenious experiments, he proved beyond scientific reproach that the "maps" in the human brain—the areas responsible for particular functions—were not hard wired but were capable of reorganizing themselves with experience. He established the conditions that are required for plastic changes in the brain (i.e. long lasting reorganization),

1. Motivation: To achieve plastic change, there must be sufficient motivation to perform the repetitive motions required for such change
2. A reward or punishment system that incentivizes the desired changes and releases the chemicals needed to make these changes in the brain long lasting.
3. Intense focus: plastic changes can only occur with intense focus which creates the right conditions for strengthening the relationship between neurons in the brain and is also responsible for activating the part of the brain—the nucleus basalis—that actually facilitates plastic changes in the brain.

He also established other fundamental principles of neuroplasticity through his experimentation:

1. Neurons that fire together in time wire together: parts of our brain that work together often become second nature to us over time. For example, a seasoned pianist over time does not think much while hammering out a Beethoven tune. That’s largely because the part of their brain responsible for this behavior has been reshaped by experience.
2. Competitive neuroplasticity: “use it or lose it”. There is heavy competition for cortical real estate in the brain and any brain maps that are not used for extended periods of time are taken over by other functions. This explains why, for example, blind people may possess heightened senses of hearing or smelling, or why we become rusty at a skill we allow to atrophy for a few years.

Merzenich did not stop there; he took the principles of neuroplasticity to the world with his program “Fast Forward” through which he has successfully treated children with autism and learning disabilities through scientifically designed exercises that motivate, reward, and encourage focus to cause plastic change to the areas of the brain that had not developed adequately during childhood. He designed a similar platform called BrainHQ to help older people delay the onset of cognitive decline.

The book goes on to introduce another scientist, Edward Taub, who took the principles of neuroplasticity to the area of stroke rehabilitation. He developed CI (Constraint Induced) therapy to overcome learned nonuse that often occurs with strokes; patients who become weaker in one part of the body due to the stroke compensate by using the unaffected part to do routine activities which, through the principles of neuroplasticity, reinforces the brain pathways that keep the affected part non-usable.

Constraint Induced therapy uses the same principles of neuroplasticity to teach the brain how to use the once affected part:

1. It constrains, for example, the "good" arm while the person must use the affected one for day to day activities.
2. Instead of rewarding a complete action, it uses "shaping" wherein even the first step towards an action is rewarded.
3. Massed practice, which is several concentrated hours of practice of a particular function, is used to rewire the brain and teach it that the affected part is, in fact, usable.

All of these principles together teach the brain to rewire itself such that even though a part of the brain has been damaged, the function for the affected body part can be effectively taken over by the remaining “good” parts of the brain.

Taub's work is both famous and infamous. The Society for Neuroscience cited his technique to treat stroke patients as one of the top 10 Neuroscience accomplishments of the 20th century; he was awarded the 2004 Distinguished Scientific Contribution Award from the American Psychological Association. On the other hand, for his research on monkeys at the infamous Silver Springs Lab to develop this technique, he was embroiled in a decade long legal battle with PETA during which his career was stalled, his monkeys confiscated, and his scientific reputation tarnished. He fought hard to appeal the charges against him and managed to get his research back on track after a vicious and tumultuous decade of fighting for his right to do science. At the age of 91, he continues to help stroke victims regain the lives they once had.

The other chapters of the book talk about the application of neuroplasticity to healing trauma, healing phantom pain in the body, and understanding love and attraction. Perhaps the biggest paradox of all of this is that the same plasticity that enables us to change our brains for the better also enables us to entrench ourselves even deeper in our existing ways. The same thing that makes us flexible makes us equally inflexible. The human mind is an incredible thing. Indeed, look at what we are capable of.