ettes ▁( elect ro des ) ▁are ▁again ▁like ▁those ▁for ▁patch ▁cl amp ▁pulled ▁from ▁glass ▁cap ill aries , ▁but ▁the ▁p ore ▁is ▁much ▁smaller ▁so ▁that ▁there ▁is ▁very ▁little ▁ion ▁exchange ▁between ▁the ▁int rac ell ular ▁fluid ▁and ▁the ▁electro ly te ▁in ▁the ▁pip ette . ▁The ▁resistance ▁of ▁the ▁mic rop ip ette ▁electro de ▁is ▁tens ▁or ▁hundreds ▁of ▁M Ω . ▁O ften ▁the ▁tip ▁of ▁the ▁electro de ▁is ▁filled ▁with ▁various ▁kinds ▁of ▁d yes ▁like ▁Luc ifer ▁yellow ▁to ▁fill ▁the ▁cells ▁recorded ▁from , ▁for ▁later ▁confirm ation ▁of ▁their ▁morph ology ▁under ▁a ▁mic ros cope . ▁The ▁d yes ▁are ▁inject ed ▁by ▁applying ▁a ▁positive ▁or ▁negative , ▁DC ▁or ▁p uls ed ▁voltage ▁to ▁the ▁electro des ▁ ▁depending ▁on ▁the ▁polar ity ▁of ▁the ▁d ye . ▁ ▁Ext rac ell ular ▁recording ▁ ▁Single - unit ▁recording ▁ ▁An ▁electro de ▁introduced ▁into ▁the ▁brain ▁of ▁a ▁living ▁animal ▁will ▁detect ▁elect rical ▁activity ▁that ▁is ▁generated ▁by ▁the ▁neur ons ▁adjacent ▁to ▁the ▁electro de ▁tip . ▁If ▁the ▁electro de ▁is ▁a ▁micro elect ro de , ▁with ▁a ▁tip ▁size ▁of ▁about ▁ 1 ▁mic rom et re , ▁the ▁electro de ▁will ▁usually ▁detect ▁the ▁activity ▁of ▁at ▁most ▁one ▁neur on . ▁Rec ording ▁in ▁this ▁way ▁is ▁in ▁general ▁called ▁" single - unit " ▁recording . ▁The ▁action ▁potential s ▁recorded ▁are ▁very ▁much ▁like ▁the