Transcranial magnetic stimulation (TMS) is a method which allows researchers to non-invasively stimulate the brain in humans. To understand how TMS activates the brain, we can record neural activity using methods such as electroencephalography (EEG). EEG involves placing sensors on the scalp and recording the small fluctuations in electrical activity that occur as neurons fire (also known as brain waves). Combined TMS-EEG is becoming very popular as a new method for assessing brain structure and function, and many researchers are using this technique to study the brain mechanisms underlying severe mental and neurological disorders.


Using EEG with TMS is extremely difficult, as the TMS pulse causes numerous artifacts in EEG recordings which obscure these small brain signals. To overcome these limitations, a group of international researchers from Australia, Finland, Canada and the US lead by Dr. Rogasch developed TESA (the TMS-EEG signal analyser). TESA is an open-source toolbox for cleaning and analysing TMS-EEG data which works in EEGLAB, one of the world’s most popular open-source EEG analysis software. Importantly, all of the code for TESA is freely available, meaning anyone can replicate analysis performed with TESA. Furthermore, TESA works through the EEGLAB graphical user interface, meaning that all functions can be accessed using point-and-click, removing the need for any coding knowledge by the user. To accompany our paper which introduced TESA to the research community, we also wrote a free online book which provides a step-by-step description on how to use TESA to perform TMS-EEG analysis. As such, TESA opens TMS-EEG analysis to all researchers, including those learning how to use the technique.

Rogasch, N. C., Sullivan, C., Thomson, R. H., Rose, N. S., Bailey, N. W., Fitzgerald, P. B., Farzan, F., Hernandez-Pavon, J. C. (2017). Analysing concurrent transcranial magnetic stimulation and electroencephalographic data: a review and introduction to the open-source TESA software. NeuroImage. Feb 15;147:934-951.

For full text, please click here.

To access the open-source toolbox (TESA) click here, and for the user manual please click here.


People Involved

Nigel Rogasch