I had the pleasure of spending a day last week talking with a world authority on brain plasticity issues, Harvard professor Alvaro Pascual-Leone. Dr. Pascual-Leone has employed a special tool in many of his studies, both to document brain change, and to induce it for the benefit of patients. That tool is direct magnetic stimulation of the brain. A very powerful magnetic pulse applied externally over the scalp can be localized to excite a limited brain area. Alvaro and his colleagues showed, historically, that they could actually reconstruct the orderly representations of body movements in the brain by systematically moving the site of stimulation across the surfaces of your skull. Moving from the top of the head down toward the ears, they evoke fine movements from the feet then legs then trunk then arm then wrist then hand and digits then face. Among many interesting plasticity studies, they then trained individuals to improve their control of particular movements of the hand, and showed that those movements GREW in extent as a result, manifesting progressive plastic changes in hand movement representations induced by training.
Dr. Pascual-Leone — and other investigators in the Neurology Institute at NIH and in other world neurology laboratories — have conducted a substantial variety of such studies documenting the fact of large-scale brain plasticity in human brains. Especially over the past decade, medical scientists have also tried to employ such stimulation to drive enduring, helpful plastic changes in the brains of individuals in need of help. In some applications, stimulation is applied in forms that are believed to suppress activity in underlying cortical areas (e.g., to weaken a source of activity that might be generating epileptic seizures; persistent pain; etc.). In other applications, stimulation is applied to activate a source of ‘corrective’ activity (e.g., to activate a cortical area contributing to positive feelings, to help chronically depressed patients).
Interestingly, these medical strategies have evolved empirically without scientific documentation of EXACTLY what changes in cortical activities are induced by magnetic stimulation. Alvaro and I have agreed to try to answer these fundamental questions together, once and for all, because the answers can clarify ways in which these strategies can be more effectively and broadly applied — and can further inform us about both positive and negative consequences of its use.
If you are interested in meeting this great Spanish-American neurologist talk about this science in his own words, check out the video below:
