A physiological interpretation is presented of ERP parameters, in rela
tion to their origin. This interpretation is based on the type of the
electric contribution of every active neuron to the ERP wave registere
d. Through the solid-angle theorem it is shown that an active neuron c
ontributes to the ERP with a low electric potential while its activati
on lasts. This gives a physiological meaning to the parameters which d
escribe the ERP wave.