Mental Practice

 "mental simulation of movements activates some of the same central neural structures required for the performance of the actual movements.  In so doing, mental practice alone seems to be sufficient to promote the modulation of neural circuits involved in the early stages of motor skill learning.  This modulation not only results in marked improvements in performance, but also seems to place the subjects at an advantage for further skill learning with minimal physical practice.  The combination of mental and physical practice leads to greater performance improvement than does physical practice alone, a phenomenon for which our findings provide a physiological explanation."
From Musicophilia: Tales of Music and the Brain by Oliver Sacks

An excellent reminder that practicing is not about wiggling our fingers for a set amount of time, but about being mindful.  During his residency last month, Mark Nuccio talked about how he was practicing for 10 hours a day in grad school but that all of this practice was not necessarily with the instrument.