Many of the listed explanations are intended for those who are not familiar with TMS technology.
Modes of magnetic stimulation
Related to experiments
Related to instrumentation
| MS | general term for magnetic stimulation, including TMS and stimulation of the peripheral nervous system |
| TMS | general term for all modes of transcranial magnetic stimulation |
| rTMS | repetitive magnetic stimulation |
| single-pulse TMS | non-repetitive TMS |
| low-frequency TMS slow TMS | repetition rate below 1 Hz |
| high-frequency TMS rapid-rate TMS | repetition rate above 1 Hz |
| dual-pulse TMS paired-pulse TMS | stimulation with two distinct stimuli through the same coil at a range of different intervals; the intensities can be varied independently |
| quadruple-pulse TMS | as dual-pulse stimulation, but with 4 pulses |
| double TMS | stimulation with two stimulation coils applied to different cerebral loci; the timing and stimulus intensity are adjusted separately |
| multichannel TMS | TMS with multiple (say, 20-100) coils that are independently controlled |
| TMS mapping | performed by changing the coil position above the head while observing its effects |
| EMG | electromyography, recording of electrical activity associated with muscle movements |
| MEP | motor-evoked potential; an excitatory response to TMS |
| kindling | seizure induction with many subconvulsive stimuli; has never been observed in TMS or rTMS |
| silent period | an inhibitory response to TMS; a period after the stimulus during which a second stimulus is ineffective |
| threshold intensity | the smallest intensity of TMS that causes measurable responses |
| 8-shaped coil (also: buttefly, figure-of-eight, double) | a stimulating coil with two planar wings with opposing current directions; induces a better focused electric field than a circular coil |
| coil current i | the current circulating in the coil; typically one (biphasic) or more (oscillating) sinusoidal pulses |
| current rise time | rise time of the coil current from zero to peak, often around 70-100 ms |
| electric field E | nerves are excited with E, which is induced by a changing B; hence, pulsed magnetic fields are needed for nervous excitation |
| magnetic field B | The tissue is entirely transparent to B and hence the intensity of B does not describe the efficacy of stimulation; often about 2 tesla on the coil surface and 0.5 T in the cortex |
| rate of change of current di/dt | maximum occurs always in the beginning of the current pulse, being equal to capacitor voltage or coil inductance; typically, 150 A/ms |
| stimulator output | often expressed in % of the maximum output; should be used cautiously, since output varies among stimulator units |
| thyristor | a semiconductor switch capable of handling high peak currents in a short time; used to discharge the power capacitor trough the coil |
Original content by Jarmo Ruohonen, updated and converted to HTML 4.0 by Jussi Nurminen
To BioMag TMS page