Meeting #7: the baseline period before a TMS pulse, 25th July 2025, 14:00 (GMT+1)

[TheHandLab]

Dear all,

the last (or first!) meeting of TMS Multi Lab was very informative, with Jason & Justin discussing how important it is to be consistent when recording EMG signals during TMS. What I took from the meeting is: if you use surface EMG recordings (most TMS people do), then there is no 'absolute' EMG (or MEP) amplitude - everything is relative to the person tested, the skill and precision of electrode placement, the noisiness of the testing environment, and how the data are analysed; controlling for all of this is hard, so we always need some measure of the maximum EMG signal recordable in each experiment. I've already changed my standard EMG analysis code and protocols since the meeting, and we updated the wiki with lots of resources here: https://github.com/TMSMultiLab/TMSMultiLab/wiki/EMG

the next meeting of TMSMultiLab will be on 25th July 2025 at 14:00 BST (GMT+1 / UTC+1). The meeting will be lead by Roisin McMackin @RMcM-Physiol on the topic of the EMG baseline period before TMS. Roisin may well change the topic or content between now and then, but that's the plan.

There is a well-known relationship between the level of background EMG activity before TMS and the size of the MEP that follows. Roisin presented a poster at TMS@40 that showed (if I recall correctly...) some very surprising and sensitive links between the background 'noise' and the MEP amplitudes. Should we use the baseline as a covariate, an exclusion, or something else..? We may find out in 2 weeks' time!

Following some sensible advice, the monthly meeting link is now permanent, so you can add this link into your regular calendar entry for these meetings:

https://bham-ac-uk.zoom.us/j/86201752364?pwd=LnSPVYuBDGa5BEbFNy5SmENqcDsvpC.1

Please forward this email to any individual who may be interested in joining (but not to mailing lists please, to avoid spam). TMSMultiLab needs to grow to have maximal impact. Please think of someone who would appreciate this and invite them!

see you soon,
Nick (& on behalf of Roisin)