New Tools for Old Problems: Magnetic Stimulation to Study (and Help) the Brain

Magnetic stimulation techniques, either repetitive TMS (rTMS) or Static Magnetic Fields, allow to modulate brain activity through the skull in a non invasive and painless way. When rTMS is used, low frequencies of stimulation (≤1 Hz) produce inhibitory changes in excitability whilst higher rates (above 5 Hz) appear to produce increasing excitability Pascual-Leone et al. (J. Clin. Neurophysiol. 15(4):333–343, 1998) [1]. By using two different experimental approaches (anaestethetized cat and monkey) to study the early visual system, we show here that rTMS applied at low and high frequency has opposing effects on the EEG. These effects can be detected locally but also in a wider spatial extent. Further, we report data supporting the suppressive nature of the static magnetic stimulation. It supports the idea that static magnets could be used for different purposes ranging from experimental studies to clinical applications.