ulation . ▁ ▁This ▁technique ▁is ▁used ▁to ▁study ▁how ▁a ▁cell ▁respond s ▁when ▁electric ▁current ▁enters ▁a ▁cell ; ▁this ▁is ▁important ▁for ▁instance ▁for ▁understanding ▁how ▁neur ons ▁respond ▁to ▁ne uro trans mit ters ▁that ▁act ▁by ▁opening ▁memb rane ▁ion ▁channels . ▁ ▁Most ▁current - cl amp ▁ampl ifiers ▁provide ▁little ▁or ▁no ▁ampl ification ▁of ▁the ▁voltage ▁changes ▁recorded ▁from ▁the ▁cell . ▁ ▁The ▁" am pl ifier " ▁is ▁actually ▁an ▁elect rom eter , ▁sometimes ▁referred ▁to ▁as ▁a ▁" unity ▁gain ▁ampl ifier "; ▁its ▁main ▁purpose ▁is ▁to ▁reduce ▁the ▁elect rical ▁load ▁on ▁the ▁small ▁signals ▁( in ▁the ▁m V ▁range ) ▁produced ▁by ▁cells ▁so ▁that ▁they ▁can ▁be ▁accur ately ▁recorded ▁by ▁low - imp ed ance ▁electron ics . ▁ ▁The ▁ampl ifier ▁increases ▁the ▁current ▁behind ▁the ▁signal ▁while ▁decre asing ▁the ▁resistance ▁over ▁which ▁that ▁current ▁passes . ▁ ▁Consider ▁this ▁example ▁based ▁on ▁Oh m ' s ▁law : ▁A ▁voltage ▁of ▁ 1 0 ▁m V ▁is ▁generated ▁by ▁passing ▁ 1 0 ▁n ano am per es ▁of ▁current ▁across ▁ 1 ▁M Ω ▁of ▁resistance . ▁ ▁The ▁elect rom eter ▁changes ▁this ▁" high ▁imped ance ▁signal " ▁to ▁a ▁" low ▁imped ance ▁signal " ▁by ▁using ▁a ▁voltage ▁follow er ▁circuit . ▁ ▁A ▁voltage ▁follow er ▁reads ▁the ▁voltage ▁on ▁the ▁input ▁( ca used ▁by ▁a ▁small ▁current ▁through ▁a ▁big ▁res istor ). ▁