per ometry . ▁ ▁Elect ro graph ic ▁modal ities ▁by ▁body ▁part ▁ ▁Elect ro phys i ological ▁recording ▁in ▁general ▁is ▁sometimes ▁called ▁electro graph y ▁( from ▁electro - ▁+ ▁- graph y , ▁" elect rical ▁recording "), ▁with ▁the ▁record ▁thus ▁produced ▁being ▁an ▁electro gram . ▁However , ▁the ▁word ▁electro graph y ▁has ▁other ▁sens es ▁( including ▁elect roph ot ography ), ▁and ▁the ▁specific ▁types ▁of ▁electro phys i ological ▁recording ▁are ▁usually ▁called ▁by ▁specific ▁names , ▁constructed ▁on ▁the ▁pattern ▁of ▁electro - ▁+ ▁[ body ▁part ▁combining ▁form ] ▁+ ▁- graph y ▁( ab bre viation ▁Ex G ). ▁Rel ated ly , ▁the ▁word ▁electro gram ▁( not ▁being ▁needed ▁for ▁those ▁other ▁sens es ) ▁often ▁car ries ▁the ▁specific ▁meaning ▁of ▁int rac ard iac ▁electro gram , ▁which ▁is ▁like ▁an ▁electro card i ogram ▁but ▁with ▁some ▁invas ive ▁leads ▁( inside ▁the ▁heart ) ▁rather ▁than ▁only ▁non in vas ive ▁leads ▁( on ▁the ▁skin ). ▁Elect ro phys i ological ▁recording ▁for ▁clin ical ▁di agnostic ▁purposes ▁is ▁included ▁within ▁the ▁category ▁of ▁elect rod i agnostic ▁testing . ▁The ▁various ▁" Ex G " ▁modes ▁are ▁as ▁follows : ▁ ▁Opt ical ▁electro phys i ological ▁techniques ▁ ▁Opt ical ▁electro phys i ological ▁techniques ▁were ▁created ▁by ▁scient ists ▁and ▁engine ers ▁to ▁overcome ▁one ▁of ▁the ▁main ▁limitations ▁of ▁classical ▁techniques . ▁Class ical ▁techniques ▁allow ▁observation ▁of ▁elect