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be sprouting those nerve endings soon die because they rely on growth factors, the proteins that support their survival, to be shunted up the nerve endings that once connected to the hippocampus. Eventually, the person can no longer achieve short-term memory and learning, and dementia sets in. The result is devastating. As one saying goes, you don’t know you have Alzheimer’s because you forget where you put your car keys. You know you have Alzheimer’s when you forget what they are for.
    In his seminal study, Geddes and his colleagues showed that in this area of massive neuronal demise, something nothing short of the magical occurs. The surviving neighboring neurons begin to sprout new projections to compensate for the ones that were lost. This is a form of neuroplasticity called compensatory regeneration. For the first time, Rudy was encountering one of the most miraculous properties of the brain. It was as if a rose were plucked from a bush, and the bush next to it handed it a new rose.
    Rudy suddenly had a deep appreciation for the exquisite power and resilience of the human brain. Never count the brain out, he thought. With neuroplasticity, the brain has evolved into a marvelously adaptable and remarkably regenerative organ. Hope existed that even in a brain being damaged by Alzheimer’s, one need onlycatch it early enough, and neuroplasticity may be triggered. It’s one of the brightest possibilities for future research.
    Myth 2. The brain’s hardwiring cannot be changed
    During all the time before neuroplasticity was proved to be legitimate, medicine could have listened to the Swiss philosopher Jean-Jacques Rousseau, who argued in the middle 1700s that nature was not stagnant or machinelike but alive and dynamic. He went on to propose that the brain was continually reorganized according to our experiences. Therefore, people should practice mental exercise the same as physical exercise. For all intents and purposes, this may have been the first declaration that our brains are flexible and plastic, capable of adapting to changes in our environment.
    Much later, in the middle of the twentieth century, American psychologist Karl Lashley provided evidence for this phenomenon. Lashley trained rats to seek out food rewards in a maze and then removed large portions of their cerebral cortex, bit by bit, to test when they would forget what they had previously learned. He assumed, given how delicate brain tissue is and how totally dependent a creature is on its brain, that removing a small portion would lead to severe memory loss.
    Shockingly, Lashley found that he could take out 90 percent of a rat’s cortex, and the animal still successfully navigated the maze. As it turned out, in learning the maze, the rats create many different types of redundant synapses based on all their senses. Many different parts of their brains interact to form a variety of overlapping sensory associations. In other words, the rats were not just seeing their way to the food in the maze; they were smelling and feeling their way as well. When bits of the cerebral cortex were removed, the brain would sprout new projections (axons) and form new synapses to take advantage of other senses, using the cues that remained, however tiny.
    Here we have the first strong clue that “hardwiring” should be greeted with skepticism. The brain has circuitry but no wires; thecircuits are made of living tissue. More important, they are reshaped by thoughts, memories, desires, and experiences. Deepak remembers a controversial medical article from 1980 entitled, half in jest, “Is the Brain Really Necessary?” It was based on the work of British neurologist John Lorber, who had been working with victims of a brain disorder known as hydrocephalus (“water on the brain”), in which excessive fluid builds up. The pressure that results squeezes the life out of brain cells. Hydrocephalus leads to retardation as well as other severe damage and even death.
    Lorber