Single-pulse TMS (Bistim2, Magstim, UK) with a 50mm figure-of-eight coil (P/N4186-00,Magstim, UK) will be used to assess cortical excitability from the M1 region of both the ipsilesional and contralesional hemispheres under the guidance of a frameless stereotactic neuronavigation system (Brainsight, Rogue Research, Montreal, Quebec, Canada). Each infant's MRI will be projected onto the neuronavigation system to assist with localization of the motor cortex (T1 MPRage).