<qa>  What is the first and second aim of the study?The first and second aim will focus on the physiological aspects of BoNT therapy in PCD. The investigators plan to determine the cortical and corticospinal physiologic changes at the time of peak BoNT effects BoNT ON which are typically seen around 4-8 weeks after the injections and at the time of wearing off related to BoNT therapy which will correspond to the time of the next injection cycle BoNT OFF. The third aim will help the investigators understand the physiological differences between clinical responders and non-responders. Healthy controls will be enrolled for normative physiological data. The main significance of this study is advancement of physiological knowledge related to BoNT therapy in subjects with PCD. 