Mar 18 2008
I recently read a fascinating book, The Brain That Changes Itself by Norman Doidge. He describes case histories and research indicating that the brain is far more malleable than we once thought. We used to think each function was localized to a small area of the brain and if you lost that area of brain tissue the function was gone forever. We once thought you couldn’t teach an old dog new tricks. Now we know better.
Learning a new skill actually changes the structure and function of the brain, even into old age. If you exercise one finger, the area of the brain devoted to that finger enlarges. The old concept of dedicated brain areas for specific functions no longer holds. Areas of the cortex that normally process vision can learn to process totally different inputs such as hearing. This is what happens with blind people: their hearing skills are enhanced when new neural connections for hearing invade the disused visual cortex. They may not actually have better hearing acuity, but they have learned to pay more attention to auditory input and to use it to build up a representation of the world around them.
One of the more intriguing experiments he describes was in monkeys. When sensory input nerves to one arm were severed, the monkey stopped using the arm, even though the motor nerves were intact. When the good arm was put in a sling, the monkey started using the impaired arm again. When both arms were deprived of sensory input, the monkey used both arms.
Researchers hypothesized that the monkeys had “learned” that one arm didn’t work in the period right after the surgery when the spinal cord was still in spinal shock, and then never re-learned that they could use it when the shock passed. When both arms were impaired, the monkeys had to use them to survive, so they were motivated to keep trying. This has implications for treatment of stroke patients, who seem to recover much faster if their good arm is restrained.
He describes the case history of a stroke patient who recovered very little function and was dismissed from conventional rehabilitation as having reached his maximum improvement. His son worked intensively with him as if he were a small child having to learn skills for the first time. He taught him to crawl and to play simple games that one might play with an uncoordinated infant. Eventually the patient made a complete recovery. On autopsy, the stroke area was “dead” with no signs of local recovery; he had co-opted neurons from other parts of the brain to take over the lost functions. Stroke victims may not try very hard to use their affected limbs because they have learned that they don’t work, but when they are prevented from using their good limbs, they may regain more function than we ever imagined.
Patients with phantom limb pain often have the illusion that the phantom limb is unable to move. Ramachandran has cured phantom pain by producing the illusion that the limb is moving using a mirror box so that the intact limb is perceived as being where the phantom limb would be. Doidge says there was a brain map of an unmoving limb that could not be modified because there was no sensory input to modify it, but the mirror box treatment was able to create a new brain map of a moving limb.
He describes new therapies for stroke patients, autism, learning disorders, OCD and other problems. Simple exercises based on knowledge gained from research seem to be able to re-map the brain in ways that are therapeutic, and that coincidentally lead to progress in other areas. Doidge is a bit overenthusiastic, and he is a psychoanalyst who claims that psychoanalysis is another way of changing brain maps. But this is certainly an exciting area of research with potentially far-reaching implications.
Much of chronic pain is learned behavior. In his book The Anatomy of Hope Jerome Groopman, MD, describes how he was disabled for years by back pain following two unsuccessful surgeries. He eventually found a rehabilitation therapist who persuaded him to re-frame his thinking about his pain. Instead of considering it a warning that activity would hurt his body, he began to think of it as a sign that his body had become so de-conditioned that it was mistakenly protesting at normal use. He exercised despite the pain, and eventually became pain-free and fully active again.
Much of chronic illness is learned behavior. Would sufferers from chronic fatigue syndrome and fibromyalgia recover faster if they could somehow re-map their neurons into healthy patterns? What if whiplash injuries were treated to prevent the learning of illness behaviors instead of having the ”sick” role fostered by prolonged compensation litigation? Maybe instead of being sympathetic and permissive with sick people we should be providing a kind of tough-love environment and encouraging them to push the limits of their abilities.
A recent article in the New England Journal of Medicine described the effects of mild traumatic brain injury in soldiers returning from Iraq. These soldiers had a high incidence of associated health problems, but when they controlled for post-traumatic stress disorder (PTSD) and depression, there was no longer any significant association with adverse health outcome.
They discuss the implications of telling a patient he has a traumatic brain injury versus telling him he has recovered from a concussion and his symptoms are due to treatable, transient depression and/or stress reactions. They say, “…the most compelling efficacy data highlight the importance of education to normalize symptoms and provide expectation of rapid recovery.”
They pointed out that, “Screening for mild traumatic brain injury months after the injury is likely to result in the referral of a large number of persons for evaluation and treatment of nonspecific health symptoms attributed to brain injuries, with potential unintended iatrogenic consequences.”
In psychotherapy, when we delve into childhood traumas, are we reinforcing brain maps for the sick role and the victim label? Wouldn’t it be more effective to concentrate on the current life situation and reinforce what coping skills the patient already has? Instead of “Poor you, you can’t get along with your boss because your Mommy didn’t love you” what if we said, “Good for you, you’ve overcome a bad start in life and have finished school, you have a girlfriend, you have become good at making friends, and you coped with the recent death of your dog by playing sports to keep your mind off your grief. You’ve done well, so let’s look at how you can use some of those strengths and coping skills to help you solve this current problem.” What if we helped consolidate the positive brain maps and helped prevent negative brain maps from wiring together? If nothing else, the concepts of neuroplasticity can contribute to a brain-based understanding of what various psychotherapies can accomplish.
Could we prevent some illnesses from developing in the first place? I read the transcript of a psychotherapy session where the patient started talking about feeling like a little boy, and talking in a childish voice. The psychiatrist nipped it in the bud by telling her to cut the crap. If he had said, “What’s your name, little boy? How old are you? Is there anyone else there?” he could have easily persuaded his very imaginative patient that she had multiple personality disorder.
The principle is that “nerves that fire together wire together.” And of course, nerves that fire apart wire apart. Could we some day learn to use this knowledge to change addictions, food likes and dislikes, antisocial behavior patterns, sexual perversions? Could we apply the concepts of brain plasticity to enhance the placebo response? Could we reduce side effects from pharmaceuticals by building pleasant associations? The possibilities seem endless: the quacks will magnify those possibilities and scientific doctors will find that there are limits to what we can accomplish. There is potential for a lot of good, and of course there is potential for evil (mind control by sinister agencies?).
And of course, there is great potential for financial gain. Quacks will jump on the neuroplasticity bandwagon and offer their own untested treatments. Programs like The Brain Gym and the Brain Fitness Program are already out there, promising far more than they have any right to.
Recent discoveries about neuroplasticity give a whole new meaning to the phrase “mind over matter.” By encouraging repeated thoughts and repeated motor actions, we can actually re-wire the physical brain to some extent. We can monitor some of these changes with neuroimaging studies. It will be fascinating to follow this developing field in the years to come.
63 Responses to “Thoughts on Neuroplasticity”