New and useful neurostimulation systems are provided that include an implantable pulse generator dimensioned and configured for implantation in the skull of a patient. The implantable pulse generator has an electrode operatively associated with a distal end portion thereof and can be provided with adjustment means, such as an adjustable biasing member or spring arranged between the electrode to the distal end portion of the pulse generator. Also provided are systems involving networked neurostimulators that are configured and adapted to work jointly in accordance with prescribed treatment protocol to effect a desired recovery from brain injury. Such networked neurostimulation systems are particularly advantageous for effecting relatively large and/or relatively distant regions of the brain. Additionally, systems and methods for motor-evoked potential (MEP)-based neuromodulation are provided. Further, AC and/or DC stimulation can be utilized, depending on the precise implementation.