▁looking ▁at ▁the ▁individual ' s ▁brain ▁activity . ▁Activity ▁such ▁as ▁which ▁port ions ▁of ▁the ▁brain ▁light ▁up ▁during ▁any ▁situations ▁encountered . ▁ ▁If ▁an ▁electro de ▁is ▁small ▁enough ▁( mic rom eters ) ▁in ▁diameter , ▁then ▁the ▁electro phys i ologist ▁may ▁choose ▁to ▁insert ▁the ▁tip ▁into ▁a ▁single ▁cell . ▁ ▁Such ▁a ▁configuration ▁allows ▁direct ▁observation ▁and ▁recording ▁of ▁the ▁int rac ell ular ▁elect rical ▁activity ▁of ▁a ▁single ▁cell . ▁However , ▁this ▁invas ive ▁setup ▁reduces ▁the ▁life ▁of ▁the ▁cell ▁and ▁causes ▁a ▁leak ▁of ▁subst ances ▁across ▁the ▁cell ▁memb rane . ▁ ▁Int rac ell ular ▁activity ▁may ▁also ▁be ▁observed ▁using ▁a ▁spe cially ▁formed ▁( h ollow ) ▁glass ▁pip ette ▁containing ▁an ▁electro ly te . ▁ ▁In ▁this ▁technique , ▁the ▁micro scop ic ▁pip ette ▁tip ▁is ▁pressed ▁against ▁the ▁cell ▁memb rane , ▁to ▁which ▁it ▁tight ly ▁ad her es ▁by ▁an ▁interaction ▁between ▁glass ▁and ▁lip ids ▁of ▁the ▁cell ▁memb rane . ▁ ▁The ▁electro ly te ▁within ▁the ▁pip ette ▁may ▁be ▁brought ▁into ▁fluid ▁continu ity ▁with ▁the ▁cy top las m ▁by ▁deliver ing ▁a ▁pul se ▁of ▁negative ▁pressure ▁to ▁the ▁pip ette ▁in ▁order ▁to ▁ru pt ure ▁the ▁small ▁patch ▁of ▁memb rane ▁enc irc led ▁by ▁the ▁pip ette ▁rim ▁( who le - cell ▁recording ). ▁Alternatively , ▁ion ic ▁continu ity ▁may ▁be ▁established ▁by ▁" per for ating "