“…In clinical practice, these potentials are recorded using electrodes which are positioned on the skull surface, according with the International System 10–20 (SI 10–20) of the American Society of Eletroencephalography 7 . Nonetheless, there is no consensus in relation to the number and positioning of the live electrodes, having seen that some authors use only one live electrode placed on Cz 8 , 9 , 10 , 11 , others use two live electrodes, placed on Fz and Cz 12 , 3 , 13 , Fz and Pz 14 , Cz and Pz 15 , 16 , or even three live electrodes, placed on Fz, Cz and Pz 17 .…”