▁bar rier ▁moment arily ▁and ▁allows ▁free ▁passage ▁of ▁chemical s ▁into ▁the ▁brain . ▁Ult imately ▁the ▁goal ▁for ▁drug ▁delivery ▁is ▁to ▁develop ▁a ▁method ▁that ▁maxim izes ▁the ▁amount ▁of ▁drug ▁in ▁the ▁lo ci ▁with ▁as ▁little ▁de grad ed ▁in ▁the ▁blood ▁stream ▁as ▁possible . ▁ ▁Ne ur om od ulation ▁is ▁a ▁technology ▁currently ▁used ▁for ▁patients ▁with ▁movement ▁dis orders , ▁although ▁research ▁is ▁currently ▁being ▁done ▁to ▁apply ▁this ▁technology ▁to ▁other ▁dis orders . ▁Rec ently , ▁a ▁study ▁was ▁done ▁on ▁if ▁DB S ▁could ▁improve ▁de pression ▁with ▁positive ▁results , ▁indicating ▁that ▁this ▁technology ▁might ▁have ▁potential ▁as ▁a ▁ther apy ▁for ▁multiple ▁dis orders ▁in ▁the ▁brain . ▁DB S ▁is ▁limited ▁by ▁its ▁high ▁cost ▁however , ▁and ▁in ▁developing ▁countries ▁the ▁avail ability ▁of ▁DB S ▁is ▁very ▁limited . ▁A ▁new ▁version ▁of ▁DB S ▁is ▁under ▁investigation ▁and ▁has ▁developed ▁into ▁the ▁novel ▁field , ▁opt ogen et ics . ▁Opt ogen et ics ▁is ▁the ▁combination ▁of ▁deep ▁brain ▁stim ulation ▁with ▁fi ber ▁opt ics ▁and ▁gene ▁ther apy . ▁Ess entially , ▁the ▁fi ber ▁opt ic ▁c ables ▁are ▁designed ▁to ▁light ▁up ▁under ▁elect rical ▁stim ulation , ▁and ▁a ▁protein ▁would ▁be ▁added ▁to ▁a ▁neur on ▁via ▁gene ▁ther apy ▁to ▁ex cite ▁it ▁under ▁light ▁stim uli . ▁So ▁by ▁combining ▁these ▁three ▁independent ▁fields , ▁a ▁sur geon ▁could ▁ex cite ▁a ▁single ▁and ▁specific ▁neur