Quadripulse stimulation (QPS) is a patterned repetitive transcranial magnetic stimulation (rTMS) protocol that induces long term potentiation (LTP) and depression (LTD) like after-effect [1]. The after-effect of QPS, compared to another patterned rTMS protocol–theta burst stimulation, was reported to be stronger and less variable across participants [2]. Moreover, the after-effect of QPS is not affected by gene-polymorphisms of BDNF [3], often influencing the rTMS after-effect [4]. Therefore, QPS emerges as a promising rTMS protocol for neuro-modulational research and treatment.

Recently, Deymed Diagnostic has developed a new stimulator specifically designed for QPS (DuoMAG MP-Quad, https://deymed. com/duomag-qps), which appears as a promising QPS-stimulator [5]. However, the after-effect induced by the DuoMAG MP-Quad has not yet been systematically investigated. The degree of after-effect may differ between QPS-stimulators considering that the waveform of stimulation pulses slightly differs between manufacturers [6]. We thus studied the QPS after-effects induced by the DuoMAG MP-Quad stimulator.