1. A system to facilitate locating an optimal site within a brain of a patient for deep brain stimulation, said system comprising: a main cannula having an internal lumen; a guiding cannula configured to pass through said lumen of said main cannula and to guide a microelectrode into said brain, said guiding cannula having a bent distal end portion; a depth adjustment mechanism configured to adjust an insertion depth of said guiding cannula; and a longitudinal angle adjustment device configured to adjust a longitudinal angle of said guiding cannula; wherein said depth adjustment mechanism and longitudinal angle adjustment device adjust a position of said guiding cannula such that said microelectrode locates said optimal site for said deep brain stimulation.