For the first time, scientists studying how the brain reorganizes itself have shown that they can modify this process using a technique called transcranial magnetic stimulation (TMS). The finding suggests new ways to helppeople recover normal function after stroke, amputation, and other injuries.
TMS is a non-invasive technique that consists of a magnetic field emanating from a wire coil held outside the head. The magnetic field induces an electrical current in nearby regions of the brain. While TMS is often used to diagnose brain abnormalities, this report shows that it also can influence brain plasticity, or reorganization. This plasticity is thought to be responsible for much of the recovery seen in people who have suffered brain damage due to trauma, stroke, or other problems. The study, conducted by researchers at the National Institute of Neurological Disorders and Stroke (NINDS), is published in the February 1 issue of The Journal of Neuroscience (1).
Many studies in the last two decades have shown that the brain continually responds to changes in stimuli by reorganizing itself. These changes are often beneficial. For example, people who have been blind from an early age often use part of the brain region normally employed for vision to process sensations from their fingertips, which helps them read Braille. However, in other cases, brain reorganization may lead to problems such as phantom pain, which often develops after amputation. This study suggests that researchers might be able to use TMS or other strategies to enhance plasticity when it is beneficial (as in the blind) and to decrease it when it is harmful (as with phantom pain).
In the new study, researchers Leonardo G. Cohen, M.D., Ulf Ziemann,
M.D., and Brian Corwell used a simple tourniquet around the elbow to shut off
the blood supply to the forearm, blocking nerve signals to the brain and
temporarily mimicking what occurs after amputation.
Contact: Natalie Larsen
NIH/National Institute of Neurological Disorders and Stroke