A new method of TMS has been developed by a researchers at the Institute of Neurology at University College London spearheaded by John Rothwell. This new method produces rapid, consistent and controllable changes in the motor cortex that last over an hour. This could lead to more useful research and therapeutic applications.
In their studies, the researchers positioned the magnet over the motor cortex, an area that controls hand movement, and measured the movements in muscles in the participant's hands.
Initial tests at low intensities showed no long-lasting effects from the new method, so in later experimentation the intensity was increased.
The researchers found they could produce the effects using short bursts of low-insensity pulses over a short period, ranging from 20 seconds to 3 minutes. In contrast to previous TMS methods, this method was also able to favor either excitatory or inhibitory responses within the brain. Specifically, the excitatory effect of TMS builds up rapidly, within about a second, while the inhibitory effect builds up within several seconds. By adjusting the length of stimulation they were able to choose whether to have more excitation or inhibition.
"We have found these stimulation paradigms to be safe in normal subjects and capable of producing consistent, rapid, and controllable electrophysiological and behavioral changes in the function of the human motor system that outlast the period of stimulation by more than 60 minutes" concluded the researchers.
"The method may prove useful not only in the motor cortex but also in other regions of the brain for both the study of normal human physiology and for therapeutic manipulation of brain plasticity," they said.
