A process that converts synaptic vesicles to a state of competence for calcium triggered fusion with the active zone membrane by bringing the two membranes into very close proximity. Priming typically (but not always) occurs after docking (Jahn and Fasshauer, 2012). Primed vesicles are also capable of spontaneously fusing with the active zone membrane. [ http://www.ncbi.nlm.nih.gov/pubmed/15217342 http://www.ncbi.nlm.nih.gov/pubmed/23060190 ]