▁the ▁patch ▁by ▁allowing ▁ex ogen ous ▁p ore - form ing ▁agent ▁within ▁the ▁electro ly te ▁to ▁insert ▁themselves ▁into ▁the ▁memb rane ▁patch ▁( per for ated ▁patch ▁recording ). ▁ ▁Finally , ▁the ▁patch ▁may ▁be ▁left ▁int act ▁( patch ▁recording ). ▁ ▁The ▁electro phys i ologist ▁may ▁choose ▁not ▁to ▁insert ▁the ▁tip ▁into ▁a ▁single ▁cell . ▁Instead , ▁the ▁electro de ▁tip ▁may ▁be ▁left ▁in ▁continu ity ▁with ▁the ▁ext rac ell ular ▁space . ▁If ▁the ▁tip ▁is ▁small ▁enough , ▁such ▁a ▁configuration ▁may ▁allow ▁indirect ▁observation ▁and ▁recording ▁of ▁action ▁potential s ▁from ▁a ▁single ▁cell , ▁term ed ▁single - unit ▁recording . ▁Depending ▁on ▁the ▁prepar ation ▁and ▁precise ▁pla cement , ▁an ▁ext rac ell ular ▁configuration ▁may ▁pick ▁up ▁the ▁activity ▁of ▁several ▁nearby ▁cells ▁simultaneously , ▁term ed ▁multi - unit ▁recording . ▁ ▁As ▁electro de ▁size ▁increases , ▁the ▁resol ving ▁power ▁decre ases . ▁ ▁Lar ger ▁electro des ▁are ▁sensitive ▁only ▁to ▁the ▁net ▁activity ▁of ▁many ▁cells , ▁term ed ▁local ▁field ▁potential s . ▁ ▁Still ▁larger ▁electro des , ▁such ▁as ▁un ins ulated ▁need les ▁and ▁surface ▁electro des ▁used ▁by ▁clin ical ▁and ▁surg ical ▁ne uro phys i olog ists , ▁are ▁sensitive ▁only ▁to ▁certain ▁types ▁of ▁synchron ous ▁activity ▁within ▁populations ▁of ▁cells ▁number ing ▁in ▁the ▁millions . ▁ ▁Other ▁classical ▁electro phys i ological ▁techniques ▁include ▁single ▁channel ▁recording ▁and ▁am