The reviewed study sample (n = 51 experiments in ~650 participants with the majority being healthy volunteers) represents approximately 40% of all TMS-EEG studies identified during the reviewed period.
The reminder of the TMS-EEG studies (other 60%) consisted of single-pulse TMS experiments studying the TMS-evoked electrical activity and its spreading immediately after stimulation (<1 s) in the absence of pulse-effect summation, or of rTMS experiments that inspected background EEG for TMS-induced epileptiform activity for safety evaluation (for a detailed review of this aspect see Rossi et al. 2009 ).
All reviewed studies either used TMS protocols with repeated pulse administration at fixed pulse repetition frequencies (conventional rTMS protocols) or the protocols of TBS (Huang et al. 2005 (link)) or PAS (Classen et al. 2004 (link)). Within the conventional protocols, only a discrete number of frequencies were tested (0.9–1 Hz: n = 17, 5 Hz: n = 6, 10 Hz: n = 8, 20 Hz: n = 4, 25 Hz: n = 1) often in association with varying number of trains, train-duration, intertrain interval, and TMS-intensities across studies, leading to a large number of employed parameter-combinations (see tables). Three studies used very low frequencies of 0.6 Hz (Van Der Werf and Paus 2006 (link)) and 0.2 Hz (Urushihara et al. 2006 (link); Hosono et al. 2008 (link)) and are discussed separately where of interest. To reduce this parameters space, we collapse for our analysis across low-frequency (0.9–1 Hz) versus high-frequency (5 Hz and above) protocols. This grouping seems reasonable also because previous studies on motor cortex excitability have reported these two protocols to differ in terms of aftereffect-direction (suppression vs. facilitation) (e.g. reviewed in Hallett 2007 (link)). Note that no TMS-EEG study has looked at aftereffects of conventional TMS in the frequency-range between 1 and 5 Hz, where the reversal of effect-direction is to be expected. In regards to TBS and PAS, employed parameters were more uniform across studies.
Table 1 provides a summary of TMS parameters broken down by TMS-protocols (average and range over studies/experiments). The figures and Table 2 depict the results per individual study/experiment.
The reminder of the TMS-EEG studies (other 60%) consisted of single-pulse TMS experiments studying the TMS-evoked electrical activity and its spreading immediately after stimulation (<1 s) in the absence of pulse-effect summation, or of rTMS experiments that inspected background EEG for TMS-induced epileptiform activity for safety evaluation (for a detailed review of this aspect see Rossi et al. 2009 ).
All reviewed studies either used TMS protocols with repeated pulse administration at fixed pulse repetition frequencies (conventional rTMS protocols) or the protocols of TBS (Huang et al. 2005 (link)) or PAS (Classen et al. 2004 (link)). Within the conventional protocols, only a discrete number of frequencies were tested (0.9–1 Hz: n = 17, 5 Hz: n = 6, 10 Hz: n = 8, 20 Hz: n = 4, 25 Hz: n = 1) often in association with varying number of trains, train-duration, intertrain interval, and TMS-intensities across studies, leading to a large number of employed parameter-combinations (see tables). Three studies used very low frequencies of 0.6 Hz (Van Der Werf and Paus 2006 (link)) and 0.2 Hz (Urushihara et al. 2006 (link); Hosono et al. 2008 (link)) and are discussed separately where of interest. To reduce this parameters space, we collapse for our analysis across low-frequency (0.9–1 Hz) versus high-frequency (5 Hz and above) protocols. This grouping seems reasonable also because previous studies on motor cortex excitability have reported these two protocols to differ in terms of aftereffect-direction (suppression vs. facilitation) (e.g. reviewed in Hallett 2007 (link)). Note that no TMS-EEG study has looked at aftereffects of conventional TMS in the frequency-range between 1 and 5 Hz, where the reversal of effect-direction is to be expected. In regards to TBS and PAS, employed parameters were more uniform across studies.
