Stroke and the Power of Brain Plasticity
Growing your brain after a stroke
Posted Nov 05, 2016
Although we think that the adult brain remains formed and static, we are finding that the brain changes and heals itself. Even early psychologists like William James (1890) argued that our brain is flexible and changing when he wrote The Principles of Psychology. He called this “plasticity”. But it took another 70 years to provide evidence for this concept. One of the first pioneers was Joseph Altman who first discovered brain cell regeneration—or neurogenesis—in 1962. More recently, by 1999 the psychologist Elizabeth Gould of Princeton University reported that memories can be recorded in neurons that are generated daily.
We are now in the age of bran plasticity. Neurologists and psychologist accept the idea that the brain and its function are not fixed throughout adulthood. Brain plasticity refers to the brain's ability to change throughout life. We continue to learn because the brain keeps reorganizing itself and forming new connections between brain cells. And we have come to understand the method the brain uses to change. Donald Hebb in 1949 wrote The Organization of Behavior and provided us with the Hebbian Theory which specifies that neurons that fire together wire together. If I reward a behavior, my brain will associate that behavior with the reward and encourage that brain connection. In the 1950, after his father suffered a massive stroke, the New York neurologist Paul Bach-y-Rita became interested in how the brain can receive information from different organs. He invented an electrically stimulated chair. Behind the chair, a large camera scanned the area, sending electrical signals of the image to four hundred vibrating stimulators on the chair against the patient's skin. The blind patient could “see” the diffuse image from the senses on his back. He developed this technique into a tongue sensor that goes on top of the tongue while wearing a camera that translates the image to these tongue sensors. The tongue replaces the eye and receives the feedback that the brain “sees”. More recently these techniques have been popularized by Michael Merzenich and Norman Doidge. They developed the idea of both positive and negative plasticity.
We all appreciate positive plasticity. We develop memories and learn new things. Our neurons and white matter that comprise our brain organize in such a way that we form an internal representation of learning and experiences. Representing multiple impressions of the same event under different criterion (smell, look, feel, association, importance, relevance etc.) With positive plasticity we learn new skills and improve our thinking by developing better and more efficient communication between sensory and motor pathways. But with negative plasticity we have followed exactly the same growth but for the wrong outcome. We learn how to behave in ways that are not helpful, and this is not intentional. Negative plasticity causes an increased sense of pain, drug use and compulsive behavior among other negative behaviors. Pain, for example, is generated in the brain, and the only way to stop pain is to retrain the brain. Opioids lead to morphine and eventually leads to a situation where no medication is able to stop the brain from feeling the pain. We have retrained the brain to develop more neural pathways to feel the pain every time we try and numb the pain by medication. The death of Prince and Michael Jackson is a testament to how strong the brain is in feeling pain.
Stroke offers us a window into how fast and dramatic brain plasticity can be. A stroke occurs when a part of the brain dies. It can be caused by a blood clot or obstruction of an artery (Ischemia). Or alternatively where a ruptured artery and the neurons are flooded (Hemorrhage). There are other repercussions from these two events, with an accumulation of fluid/pressure on the brain (Edema) and the disruption of the sodium-potassium pump.
In the Copenhagen stroke study, a study headed by Henrik Jørgensen from Bispebjerg Hospital, Copenhagen, Denmark reported that one in five stroke patients died in hospital, one in seven were discharged to a nursing home, and over half of stroke patients were discharged to their own home. Half of those that went home improved. What happens to these lucky quarter of the stroke victims who improve is a testament about brain plasticity. With all strokes there is a shadow that surrounds the dead tissue in the brain--penumbra. Penumbra are cells waiting to die. Whether these cells die or recover is dependent upon how fast the brain uses these cells for learning. And the clock is ticking. Every minute of delay to treatment is said to cost a patient 1.9 million brain cells. By early referral to physiotherapy, occupational therapy, and speech language pathologist services the brain heals itself.
We have an ageist view of health. Instead of referring older adults to therapy we instead shuffle them over to wards. Brain plasticity is still available for older adults. But in our ageist view we judge older adults as ready to die and we fulfill this judgement by not helping their brain become re-engaged.
© USA Copyrighted 2016 Mario D. Garrett