The "Fast Track" is intended for students who are certain that they want to affiliate with the Neuroscience Program -- their course requirements are:

The "Traditional Track" is intended for students who are interested in neuroscience but want to keep their options open so that they may affiliate with a different GSBS Program if they choose. These students take the GSBS core course, GS21 1017 Foundations of Biomedical Research, in addition to the courses listed above.  

Students who take the fast track will complete their course requirements in two semesters whereas those who follow the traditional track will complete their requirements in three semesters.