Optimizing Functional Accuracy of TMS in Cognitive Studies: A Comparison of Methods
International Clinical TMS Certification Course
The Academy of Brain Stimulation
Transcranial magnetic stimulation (TMS) is a tool for inducing transient disruptions of neural activity noninvasively in conscious human volunteers.
In recent years, the investigative domain of TMS has expanded and now encompasses causal structure–function relationships across the whole gamut of cognitive functions and associated cortical brain regions.
Consequently, the importance of how to determine the target stimulation site has increased and a number of alternative methods have emerged.
Comparison across studies is precluded because different studies necessarily use different tasks, sites, TMS conditions, and have different goals.
Therefore, in this study four commonly used TMS coil positioning approaches were systematically compared by using them to induce behavioral change in a single cognitive study.
Specifically, the behavioral impact of right parietal TMS during a number comparison task was investigated, while basing TMS localization either on (i) individual fMRI-guided TMS neuronavigation, (ii) individual MRI-guided TMS neuronavigation, (iii) group functional Talairach coordinates, or (iv) 10–20 EEG position P4.
The exact behavioral effects induced by TMS using each approach were quantified, the standardized experimental effect sizes were calculated, and a statistical power analysis was conducted in order to calculate the optimal sample size required to reveal statistical significance.
The findings revealed a systematic difference between the four approaches, with the individual fMRI-guided TMS neuronavigation yielding the strongest and the P4 stimulation approach yielding the smallest behavioral effect size.
Accordingly, power analyses revealed that although in the fMRI-guided neuronavigation approach five participants were sufficient to reveal a significant behavioral effect, the number of necessary participants increased to n = 9 when employing MRI-guided neuronavigation, to n = 13 in case of TMS based on group Talairach coordinates, and to n = 47 when applying TMS over P4.
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These graded effect size differences are discussed in light of the revealed interindividual variances in the actual target stimulation site within and between approaches.
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Read the full publication here.
Alexander T. Sack, Roi Cohen Kadosh, Teresa Schuhmann, Michelle Moerel, Vincent Walsh, Rainer Goebel; Optimizing Functional Accuracy of TMS in Cognitive Studies: A Comparison of Methods. J Cogn Neurosci 2009; 21 (2): 207–221. doi: https://doi.org/10.1162/jocn.2009.21126
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1 年fMRI guided TMS neuronavigation makes sence to me but like all things that are very new it needs time to gain acceptance and get established. EEG in TMS has merit as well and much easier proposition if done with current dry EEG systems but its not reimbursed either... So we have all the option. We offer a package of both for $ 1000 at the moment for a limited time to qualifying patients