Excerpted from the book: The Brain That Changes Itself
Stories of Personal Triumph from the Frontiers of Brain Science
By Norman Doidge, MD, Penguin Publishing, December, 2007
The arrival of Bill Jenkins at Michael Merzenich's lab ushered in a new phase of research that would help Merzenich develop practical applications of his discoveries. Jenkins, trained as a behavioral psychologist, was especially interested in understanding how we learn. He suggested they teach animals to learn new skills, to observe how learning affected their neurons and maps.
In one basic experiment they mapped a monkey's sensory cortex. Then they trained it to touch a spinning disk with its fingertip, with just the right amount of pressure for ten seconds to get a banana-pellet reward. This required the monkey to pay close attention, learning to touch the disk very lightly and judge time accurately. After thousands of trials, Merzenich and Jenkins remapped the monkey's brain and saw that the area mapping the monkey's fingertip had enlarged as the monkey had learned how to touch the disk with the right amount of pressure. The experiment showed that when an animal is motivated to learn, the brain responds plastically.
The experiment also showed that as brain maps get bigger, the individual neurons get more efficient in two stages. At first, as the monkey trained, the map for the fingertip grew to take up more space. But after a while, individual neurons within the map became more efficient, and eventually fewer neurons were required to perform the task.
This more efficient use of neurons occurs whenever we become proficient at a skill, and it explains why we don't quickly run out of map space as we practice or add skills to our repertoire.
Fast ForWord is the name of the training program they developed for language-impaired and learning-disabled children. The program exercises every basic brain function involved in language from decoding sounds up to comprehension — a kind of cerebral cross-training.
This "reward" is a crucial feature of the program, because each time the child is rewarded, his brain secretes such neurotransmitters as dopamine and acetylcholine, which help consolidate the map changes he has just made. (Dopamine reinforces the reward, and acetylcholine helps the brain "tune in" and sharpen memories.)
Merzenich claims that when learning occurs in a way consistent with the laws that govern brain plasticity, the mental "machinery" of the brain can be improved so that we learn and perceive with greater precision, speed, and retention. Clearly when we learn, we increase what we know. But Merzenich's claim is that we can also change the very structure of the brain itself and increase its capacity to learn. Unlike a computer, the brain is constantly adapting itself.
"The cerebral cortex," he says of the thin outer layer of the brain, "is actually selectively refining its processing capacities to fit each task at hand." It doesn't simply learn; it is always "learning how to learn."
It is Merzenich who has made the most ambitious claims for the field: that brain exercises may be as useful as drugs to treat diseases as severe as schizophrenia; that plasticity exists from the cradle to the grave; and that radical improvements in cognitive functioning — how we learn, think, perceive, and remember — are possible even in the elderly.
His latest patents are for techniques that show promise in allowing adults to learn language skills, without effortful memorization. Merzenich argues that practicing a new skill, under the right conditions, can change hundreds of millions and possibly billions of the connections between the nerve cells in our brain maps.
"The most frustrating thing," says Merzenich, "was that I saw that neuroplasticity had all kinds of potential implications for medical therapeutics — for the interpretation of human neuropathology and psychiatry. And nobody paid any attention."
If this post strikes a chord with you, we take brain plasticity possibilities a step further in Impossible Dream, the extraordinary story of triumph over disability told from the first-person perspective of a young woman living with autism.