| |
You are here: Experts > Science > Neurosciences > Neuroscience > TMP, TMS
Expert: Kai Schreiber
Date: 11/30/2007
Subject: TMP, TMS
Question
QUESTION: When using TMP or TMS a magnetic field is used to stimulate a part of the human brain, much like its natural processes. What kind of magnetic field is used and what frequency is it? does it variate with different parts/functions of the brain? I presume that it is low voltage and possibly even frequency.
ANSWER: Hi Daniel,
there is different kinds of TMS, but in general, the idea is to use a quick and strong pulse to induce eddy currents in the conductive tissue and trigger action potentials and neuronal activity with that. The exact mechanism of how that works, is still mainly unclear, however.
For single pulse TMS, a single such pulse is all that is delivered, and the strength of it is often determined by applying pulses of increasing strength until a desired reaction is elicited. There also is a version of TMS where repetitive pulses are delivered for longer time periods, these are then usually kept just below the threshold where single pulses would elicit a direct reaction.
Best,
Kai
---------- FOLLOW-UP ----------
QUESTION: Thank you for your answer. What frequency is the pulse usually transmitted at?
Answer
Hi Daniel,
well, as I said, for standard TMS it's a single pulse, so it just has a rising and a falling slope. Common rise time (0 to peak current) would be around 100 ms, so I guess you could call that a 1.5 Hz stimulus, if you thought about it as one half of a sine wave, but it doesn't really have a frequency assigned to it.
For repeated TMS, the frequencies of pulse repetitions are usually in the range of fractions of a Hertz to a few Hertz.
Best
Kai
Add to this Answer
Ask a Question
|
|
