Constraint Induced Therapy for Speech
The principles of constraint-induced therapy have been applied by a team headed by Dr. Friedemann Pulvermuller in Germany, which worked with Taub to help stroke patients who have damage to Broca's area and have lost the ability to speak.
About 40 percent of patients who have a left hemisphere stroke have this speech aphasia. Some, like Broca's famous aphasia patient, "Tan," can use only one word; others have more words but are still severely limited. Some do get better spontaneously or get some words back, but it has generally been thought that those who didn't improve within a year couldn't. What is the equivalent of putting a mitt on the mouth or a sling on speech? Patients with aphasia, like those with arm paralysis, tend to fall back on the equivalent of their "good" arm. They use gestures or draw pictures. If they can speak at all, they tend to say what is easiest over and over.
The "constraint" imposed on aphasiacs is not physical, but it's just as real: a series of language rules. Since behavior must be shaped, these rules are introduced slowly. Patients play a therapeutic card game. Four people play with thirty-two cards, made up of sixteen different pictures, two of each picture. A patient with a card with a rock on it must ask the others for the same picture. At first, the only requirement is that they not point to the card, so as not to reinforce learned nonuse. They are allowed to use any kind of circumlocution, as long as it is verbal. If they want a card with a picture of the sun and can't find the word, they are permitted to say "The thing that makes you hot in the day" to get the card they want. Once they get two of a kind, they can discard them. The winner is the player who gets rid of his cards first.
The next stage is to name the object correctly. Now they must ask a precise question, such as "Can I have the dog card?" Next, they must add the person's name and a polite remark: "Mr. Schmidt, may I please have a copy of the sun card?" Later in the training more complex cards are used. Colors and numbers are introduced — a card with three blue socks and two rocks, for instance. At the beginning patients are praised for accomplishing simple tasks; as they progress, only for more difficult ones.
The German team took on a very challenging population — patients who had had their strokes on average 8.3 years before, the very ones whom most had given up on. They studied seventeen patients. Seven in a control group got conventional treatment, simply repeating words; the other ten got CI therapy for language and had to obey the rules of the language game, three hours a day for ten days. Both groups spent the same number of hours, then were given standard language tests. In the ten days of treatment, after only thirty-two hours, the CI therapy group had a 30 percent increase in communication. The conventional treatment group had none.
Based on his work with plasticity, Taub has discovered a number of training principles: training is more effective if the skill closely relates to everyday life; training should be done in increments; and work should be concentrated into a short time, a training technique Taub calls "massed practice," which he has found far more effective than long-term but less frequent training.
Many of these same principles are used in "immersion" learning of a foreign language. How many of us have taken language courses over years and not learned as much as when we went to the country and "immersed" ourselves in the language for a far shorter period? Our time spent with people who don't speak our native tongue, forcing us to speak theirs, is the "constraint." Daily immersion allows us to get "massed practice." Our accent suggests to others that they may have to use simpler language with us; hence we are incrementally challenged, or shaped. Learned nonuse is thwarted, because our survival depends on communication.
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