In Chapter 11, Dr. Doidge introduces us to Michelle Mack, a 29-year-old who was born with only the right hemisphere of her brain. At birth, her doctors were not aware of this and now that they do know, they only have theories of what happened before birth. In order for Michelle to function well, her right hemisphere had to learn the function of the left hemisphere and economize its own function. At 29 she holds down a part time job and enjoys her family. There are some outwards signs of her lack of a left hemisphere: bent, twisted right hand that can be used for some things; brace on right leg; she is a lefty, and her left limbs are normal. Her right visual field is limited as she has a hard time seeing things coming from her right. Blindness on her right side has helped her develop an extremely keen sense of hearing. Thus, she can experience sensory overload in her hearing and touch.
During pregnancy, Michelle’s mother had some difficulties and apparently her body was trying to miscarriage. Both mom and daughter are happy it didn’t. Michelle’s parents began to notice things that indicated developmental problems – vision, motor. They noticed that she was tracking visually so she was not totally blind. Her dad noticed that she likes music and wanted to hear certain music over and over. He had her crawl to the record player to earn listening again. This helped develop her brain and function.
Michelle explained to Dr. Doidge that she would use rhyming, nonsensical words when frustrated. Concrete thinking is much easier than abstract thinking. She can play Solitaire very quickly because the decisions are very concrete. Other, more abstract decisions are more difficult for her.
Michelle demonstrated savant abilities. She could tell what day of the week a date was within the last 18 years by memory. For those dates before that time, she would have to figure it out, but still could do it quickly and accurately. Doidge told her about the work of Alexandr Luria, a Russian neuropsychologist with a memory artist who had a photographic memory. Also, he told her about “synesthetes” whose senses were “cross-wired” so that they had a color code for days of the week. Michelle said she had a scene connected with days of week.
Dr. Jordan Grafman, the chief of the Cognitive Neurosciences section of the National Institutes of Health, National Institute of Neurological Disorders and Stroke has been working with Michelle Mack. His background includes working with a woman whose brain was damaged in an assault. After five years, other doctors had given up on increasing this woman’s function. However, Grafman began an intensive program of rehab – mind and body –and the woman’s function increased. He also served our military personnel in Viet Nam. In this case as well, he saw increase in function where none was expected. He formulated a theory integrating “nondoctrinaire localization and plasticity. His research revealed four kinds of plasticity.
1) “Map Expansion” – neurons in the center of an area focus more on a task than the ones on the outer limit. Different areas compete for those peripheral neurons. The greater the demand the more likely the use for that area.
2) “Sensory Reassignment” – When one sense is blocked, another area takes over the function of the blocked sense. In blindness, the senses of hearing or touch develop more and are keener.
3)“Compensatory Masquerade” – once explained as “alternative strategies” when there is more than one way to do something.
4) “Mirror Region Takeover” – this occurs when a part of one hemisphere fails to do its job, the mirror region on the other side takes over the function as well as it can. When the damage occurs before specialization develops, function approximates “normal” more than when it is later. P. 276 This is true for Michelle, the damage was before birth, while her brain was being formed.
Michelle’s parents are making preparations for Michelle’s care after they are gone, but she is pretty happy the way she is. Doidge again introduces a person and researchers as windows into the plasticity of the brain.