Physical mechanisms in neuroelectromagnetic therapies.

Physical parameters that are used to characterize different types of electromagnetic devices used in neurotherapy can include power, frequency, carrier frequency, current, magnetic field intensity, and whether an application is primarily electric or primarily magnetic. Currents can range from tens of microamperes to hundreds of milliamperes, magnetic fields from tens of microtesla to more than one tesla, and frequencies from a few Hz to more than 50 GHz. A division into three device categories is proposed, based on the current applied and the specificity of the therapeutic signal. Two research areas have great potential for new neuroelectromagnetic strategies. Studies of endogenous neural oscillatory states suggest using external fields to reinforce or inhibit such states. Also, various independent groups have reported that weak magnetic fields, in particular ion cyclotron resonance fields, are capable of sharply altering behavior in rats.