Pharmacological Modulation of TMS-EEG
A commonly used measure in TMS-EEG research is TEP, the time-locked EEG response to a single TMS pulse. TEP is characterized by peaks and troughs lasting up to 300 ms poststimulus and is believed to represent cortical excitability and connectivity. However, its underlying neurophysiological nature remains less known. Pharmaco-TMS-EEG has opened up new opportunities for understanding the role of specific neurotransmission in TMS-EEG responses. Previous studies have shown that GABAergic and glutamatergic neurotransmissions, to some extent, shaped TEP resulting from M1 stimulation ([1],[2],[3]). It is still unclear whether other neurotransmission systems, such as cholinergic signaling, contribute to TEP while targeting cortical regions outside M1. Studying the role of cholinergic transmission is not only helpful in deciphering the neurophysiological basis of TMS-EEG responses but also in developing TMS-EEG biomarkers for disorders such as Alzheimer's disease, Parkinson’s disease, and schizophrenia. Here, we aim to investigate the effects of anticholinergic drugs, scopolamine, and biperiden, on TEP resulting from stimulating cortical regions mPFC, AG, and SMA in healthy participants. We expect that the amplitude of TEP amplitude would be altered following drug administration.
Abbreviations: AG: angular gyrus; mPFC: medial prefrontal cortex; SMA, supplementary motor area; TEPs: TMS evoked EEG potentials. TMS-EEG, Transcranial magnetic stimulation Electroencephalography.
Literature:
[1]. Premoli, I., Castellanos, N., Rivolta, D., Belardinelli, P., Bajo, R., Zipser, C., ... & Ziemann, U. (2014). TMS-EEG signatures of GABAergic neurotransmission in the human cortex. Journal of Neuroscience, 34(16), 5603-5612.
[2]. Belardinelli, P., König, F., Liang, C., Premoli, I., Desideri, D., Müller-Dahlhaus, F., ... & Ziemann, U. (2021). TMS-EEG signatures of glutamatergic neurotransmission in human cortex. Scientific reports, 11(1), 8159.
[3]. Gordon, P. C., Song, Y. F., Jovellar, D. B., Rostami, M., Belardinelli, P., & Ziemann, U. (2023). Untangling TMS‐EEG responses caused by TMS versus sensory input using optimized sham control and GABAergic challenge. The Journal of Physiology, 601(10), 1981-1998.
Project contributors: Yufei Song with Pedro Gordon
Funding: German Research Foundation (Deutsche Forschungsgemeinschaft – DFG – project number 466 458 984), European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (ConnectToBrain, ERC synergy grant agreement No. 810377)
