Cortical Silent Period in Laryngeal Dystonia

An anatomical T1 magnetic resonance image (MRI) with high resolution will be acquired on a separate day before the TMS experiment. The image will be imported into the neuronavigation system (Nexstim, Helsinki, Finland) to guide the localization of the primary motor cortex (M1) for laryngeal muscle representation. Prior to M1 mapping for laryngeal muscle representation, mapping of the representation for hand muscle representation will be performed. Hand region excitability (abductor pollicis brevis, APB) will be evaluated by using surface electrodes attached to the right-hand APB muscle. The cSP threshold is defined as the lowest TMS intensity that elicits a cSP in 5 out of 10 consecutive trials. Single-pulse cortical stimulations will be performed during the vocalization of sustained /i/ sound.