The Brain That Changes Itself
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| The Brain that Changes Itself: Stories of Personal Triumph from the frontiers of Brain Science | |
| Author | Norman Doidge |
|---|---|
| Country | United States |
| Language | English |
| Subject(s) | Neuroplasticity |
| Genre(s) | Non-fiction |
| Publisher | Viking Press |
| Publication date | 2007 |
| Pages | 427 pp |
| ISBN | ISBN 067003830X |
The Brain That Changes Itself: Stories of Personal Triumph from the frontiers of brain science is a book on neuroplasticity by psychiatrist Norman Doidge M.D. It follows the lives of several medically injured patients and details just how the brain adapts to compensate for their disabilities. Doidge unearths the previous work of Paul Broca and Bach-y-Rita to show that the brain is adaptive and thus plastic. Doidge will coin the term "neurplastician" and "the plastic paradox" but is also quick to point out the good and the bad of the brain's plasticity: "What we have learned .. is that neuroplasticity contributes to both the constrained and unconstrained aspects of our nature" and "it renders our brains not only more resourceful but also more vulnerable to outside influences."
Contents |
[edit] Skills
An important example of neuroplasticity is how we gain skills. Doidge presents an experiment performed by Pascual Leone where he mapped the brains of blind people learning to read Braille. Braille reading is a motor activity, which involves scanning with a reading finger, and a sensory activity, which involves feeling the raised bumps. The brain maintains a representation of these sensory and motor aspects and they are located on the sensory and motor cortexes respectively. The blind subjects practiced 2 hours a day, Monday through Friday, with an extra hour of homework. The mapping of their brains took place on Monday, after the weekend, and Friday, immediately after their week cram. What the scans ultimately showed is that the maps dramatically increased in size on Friday scans but returned to a "baseline" size on the following Monday. It took 6 months for the baseline Monday map to gradually increase and by 10 months they plateaued. After the blind subjects took a two month break, they were remapped, and their maps were unchanged from their last Monday mapping. What this shows is that long lasting changes as the result of skill learning took 10 months of repeated practice. The reason why short-term improvements were made based on the Friday mappings, but eventually disappeared, is the result of the type of neuronal connections that were taking place. The Friday mappings were the result of the strengthening of existing neuronal connections. Monday mappings, though showing little progress initially and plateauing at 10 months, were the result of the creation of new neural connections.
[edit] A woman perpetually falling
Doidge begins his series of case studies with a woman named Cheryl who feels as if she's "perpetually falling." The fear inevitably leads her to falling on the floor and so overwhelms her thoughts that she can't think of anything else. Doidge explains that the problem Cheryl is experiencing is a loss of balance, or a loss of Vestibular sense. The vestibular sense is maintained by hair cells in fluid canals. The ear contains three, each dedicated to different aspects of motion (horizontal, vertical, and forward and backward). When the fluid's motion excites the hairs, an electrical signal is sent to the vestibular nuclei in the brain which will then alert the body's muscles. All of this is done unconsciously so we can maintain a sense of balance.
[edit] Cure
So how does Cheryl regain her sense of balance?
Cheryl regains her sense of balance by wearing an electrode hat with a thin strip for her tongue. The hat, like the ear's natural hair cell's, detects motion and "translates it" onto a computer map. The computer map is then sent to the tongue strip with 144 electrodes. When Cheryl moves forward, a taste of chapagne bubbles arrives at the front of the tongue. When Cheryl moves backward, the feeling moves toward the back. This process allows Cheryl to stand upright and maintain balance, even though the sensations are coming from her tongue. When Cheryl removes the hat there is a "residual effect" - malfunctioning aspects of the vestibular tissue which were constantly sending signals are now quieted and the proper vestibular pathway is now reinforced. The hat also recruits other pathways, improving her vestibular sense.
[edit] Reviews
[edit] References
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