## 4 Discussion
Extensions of the work presented herein would be to move the analysis in the source space and/or expand the range of stimulation intensity values by including higher range supra-LT cases. This would allow for the more appropriate (intuitively) fitting of a sigmoid function, which in turn would lead to more meaningful extrapolations and better understanding of TMS-induced cortical activation. The promising results we report here need to be verified in a larger dataset. If so, they would constitute a further step that could lead toa paradigm shift toward the characterization of TMS on the basis of the induced E-field rather than on the stimulation intensity. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app12157437/s1](https://www.mdpi.com/article/10.3390/app12157437/s1)]([https://www.mdpi.com/article/10.3390/app12157437/s1](https://www.mdpi.com/article/10.3390/app12157437/s1)), Figure S1: As Figure 5, but for dataset A; Figure S2: As Figure 6, but for linear fits; Table S1: Adjusted \(R^{2}\) and statistical significance for the two CEAs and for individual subjects; Table S2: Adjusted \(R^{2}\) for the two CEAs and for different model fits. Conceptualization, I.V., D.K. and V.K.K. ; methodology, I.V., M.T., T.S. and V.K.K. ; software, I.V. and M.T. ; validation, I.V., T.S. and V.K.K. ; formal analysis, I.V. ; investigation, E.C. and V.K.K. ; resources, E.C., I.M., Y.R. and A.Z. ; data curation, I.V., M.T. and M.A.R. ; writing--original draft preparation, I.V. ; writing--review and editing, M.T., A.R., D.K. and V.K.K. ; visualization, I.V. ; supervision, V.K.K. ; project administration, V.K.K. ; funding acquisition, V.K.K. All authors have read and agreed to the published version of the manuscript. This work was supported by the Action \"Bilateral and Multilateral RTD cooperation between Greece and Israel\" supported by GSRT and IIA under grant agreement number 122994/14. The study was conducted in accordance with the Declaration of Helsinki and approved by the Aristotle University of Thessaloniki and National Ethics Committee (protocol code: 118371/2019 and date of approval: 14 October 2019). Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. No publicly archived datasets are available. The data are not publicly available due to privacy reasons. The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. The following abbreviations are used in this manuscript:  
Transcranial Magnetic Stimulation  
E-fields, EF  
Electric Field  
TEP  
TMS-Evoked Potential  
SI  
Stimulus Intensity  
LT  
Lower Cortical Threshold  
EEG  
Electroencephalography  
BEM  
Boundary Element Method  
FEM  
Finite Element Method  
EOG  
Electrooculography  
WBN  
White-based Noise  
ISI  
Interstimulus Interval  
MSO  
Maximal Simulator Output  
CRLS  
Conventional Recursive Least Squares Algorithm  
RANSAC  
Random Sample Consensus  
ASR  
Artifact Subspace Reconstruction  
ICA  
Independent Component Analysis  
CSD  
Current Source Density  
CEA  
Cortical Evoked Activity  
GFP  
Global Field Power  
ROI  
Region of Interest  
MT  
Motor Threshold