Activity-dependent synaptic plasticity is likely to provide a mechanism for learning and memory. Cortical synaptic responses that are strengthened within a fixed synaptic modification range after 5 days of motor skill learning, are driven near the top of their range, leaving only limited room for additional synaptic strengthening. If synaptic strengthening is a requisite step for acquiring new skills, near saturation of LTP should impede further learning or the LTP mechanism should recover following single task learning. Here we show that the initial learning-induced synaptic enhancement is sustained even long after training has been discontinued and that the synaptic modification range shifts upwards. This range shift places increased baseline synaptic efficacy back within the middle of its operating range, allowing pre-learning levels of LTP and LTD. Persistent synaptic strengthening might be a substrate for long-term retention in motor cortex, while the shift in synaptic modification range ensures the availability for new synaptic strengthening.