Objectives: This project will (1) establish the test-retest reliability of a novel transcranial magnetic stimulation-electroencephalography (TMS-EEG) interhemispheric inhibition (IHI) measure and (2) validate it against the TMS-EMG-based IHI measure (the gold standard). It will also (3) compare effects of dual-coil cortico-cortical paired associative stimulation (ccPAS) protocols with different interstimulus intervals (ISI) on this TMS-EEG-based IHI marker in poststroke patients. Methods: Study 1: IHI will be conducted in 20 stroke patients and 20 healthy counterparts using TMS-EEG and TMS-EMG; furthermore, both measures will be repeated after one week for test-retest reliability. Study 2: A randomized-crossover trial where 20 stroke patients undergo a single-session ccPAS in three separate visits (ISI: 8ms: LTD-like, 12ms: LTP-like, 100ms: sham) to investigate the differential modulatory effects in IHI.