It varies by school, by year, and whether you're applying for NSERC, CIHR or SSHRC.
I know each school has a pre-determined number of each that will be awarded to students at that school for any given year. Here is the link: https://www.nserc-crsng.gc.ca/students-etudiants/cgsallocations-quotasbesc_eng.asp. If you're in Neuro at alberta I assume you're either NSERC or CIHR, which would be a competition for 61 or 24 awards respectively (this year). If my understanding is correct, the school first reviews applications internally producing an initial ranking, then sends the applications alongside rankings to NSERC, CIHR or SSHRC for the national competition. (Exception is for students applying from year-4 undergrad for 1st-year CGS-M; theirs get forwarded automatically to national). Then another selection process occurs, producing a second ranking which the school can then use to fulfill its allotted number of each award. Those that were deemed meritous but ranked below the allotted number are wait listed I think. I do not know what determines the length of a wait list. Hope that helps somewhat