▁enough ▁so ▁that ▁small ▁neur onal ▁signals ▁can ▁be ▁disc ern ed ▁from ▁thermal ▁noise ▁in ▁the ▁electro de ▁tip ). ▁ ▁Vol t age ▁cl amp ▁ ▁The ▁voltage ▁cl amp ▁technique ▁allows ▁an ▁experiment er ▁to ▁" cl amp " ▁the ▁cell ▁potential ▁at ▁a ▁chosen ▁value . ▁This ▁makes ▁it ▁possible ▁to ▁measure ▁how ▁much ▁ion ic ▁current ▁cross es ▁a ▁cell ' s ▁memb rane ▁at ▁any ▁given ▁voltage . ▁ ▁This ▁is ▁important ▁because ▁many ▁of ▁the ▁ion ▁channels ▁in ▁the ▁memb rane ▁of ▁a ▁neur on ▁are ▁voltage - g ated ▁ion ▁channels , ▁which ▁open ▁only ▁when ▁the ▁memb rane ▁voltage ▁is ▁within ▁a ▁certain ▁range . ▁Vol t age ▁cl amp ▁measurements ▁of ▁current ▁are ▁made ▁possible ▁by ▁the ▁near - sim ult aneous ▁digital ▁sub tra ction ▁of ▁trans ient ▁capac itive ▁curr ents ▁that ▁pass ▁as ▁the ▁recording ▁electro de ▁and ▁cell ▁memb rane ▁are ▁charged ▁to ▁alter ▁the ▁cell ' s ▁potential . ▁ ▁Current ▁cl amp ▁▁▁▁ ▁The ▁current ▁cl amp ▁technique ▁records ▁the ▁memb rane ▁potential ▁by ▁inject ing ▁current ▁into ▁a ▁cell ▁through ▁the ▁recording ▁electro de . ▁ ▁Un like ▁in ▁the ▁voltage ▁cl amp ▁mode , ▁where ▁the ▁memb rane ▁potential ▁is ▁held ▁at ▁a ▁level ▁determined ▁by ▁the ▁experiment er , ▁in ▁" current ▁cl amp " ▁mode ▁the ▁memb rane ▁potential ▁is ▁free ▁to ▁vary , ▁and ▁the ▁ampl ifier ▁records ▁whatever ▁voltage ▁the ▁cell ▁generates ▁on ▁its ▁own ▁or ▁as ▁a ▁result ▁of ▁stim