The overall goal is to develop new clinical approaches to restore upper-limb function after incomplete cervical spinal cord injury (SCI). Corticospinal tract (CST) axons are involved in controlling upper-limb function. Paired pulse induced spike-timing dependent plasticity (STDP) enhances synaptic strength between residual CST axons and spinal motoneurons (SMNs) resulting in temporary improvements in upper-limb function in humans with incomplete cervical SCI. Motor training will be combined with paired-pulse STDP stimulation to further enhance plasticity and behavioral recovery.