Are there any systems available for carrying out repetitive transcranial magnetic stimulation (rTMS) and EEG recording at the same time without major artifact due to the stimulation? What would these systems be and how much do they approximately cost?
Yes it is possible, since some teams have already explored how rTMS produces it effects on behavior (see Johnson et al., 2010; Capotosto et al., 2011). They employ independent EEG and rTMS tools (i mean not a 'common' system). Moreover, recent methods as ICA would limit the effect of stimulation artifacts. In both studies, the stimulation is delivered through a 8-shaped coil connected with a standard Mag-Stim Rapid 2 stimulator and EEG recording is performed with BrainAmp amplifiers. Actually, I don't know if we dispose of more modern tools for that purpose.
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Hello,
I agree with Martin, it is possible to record simultaneous EEG with rTMS using independent systems. Also, as he points out, you will still find some major artifacts but their effect on EEG could be minimize using methods such as ICA.
However, and depending on your research questions and aims, it is much easier to deal with artifacts of tDCS on simultaenous EEG recordings. Indeed, neuroelectrics (neuroelectrics.com) have developed a combined system to stimulate and simultaneously record which is accompanied by a software with a built in solution to clear stimulation artifacts. But as I said, this option, would depende on whether you can adapt your research question to the use of tDCS instead of rTMS.
Hope this help
It is not possible to record with absolutely no artefacts, even if you are using a sample and hold (or sample and attenuate) amplifier you will still pick up some magnetic artefacts. However, it is very possible to get rid of them using ICA (Hamidi et al demonstrate the use of this method in rtms http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2850212/)
I do a lot of work with combined tms-eeg, and would be more than happy to discuss this topic further. The caveat of this is that you need to accept that ICA is not a perfect approach, thus depending on your expertise (or available expertise) I would certainly consider experimenting with a variety of approaches.
I agree with Nik. I have conducted rTMS-EEG for a number of years and found that no post-processing technique will 100% get rid of magnetic artefacts. You need to have substantial experience to conduct rTMS-EEG. Type of electrodes you use is very important as well, in addition to the hardware used to record the EEG signals. Conducting these experiments on subjects with low motor thresholds is always an advantage when it comes to reducing magnetic artefact. As Nik pointed out, you should consider experimenting with a variety of approaches. I used to sometimes experiment on cantelopes covered with towels sprayed with saline solution and then I'd connect a battery / tDCS device to induce current through it, then conduct rTMS-EEG to see the 'best' way to reduce artefacts in the data.
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