Sites of electrode placement for the electrogastrography. An indifferent electrode was set at the midpoint between the sternal xiphoid process and the umbilicus along the median line. Electrode 1 (CH1) was set at the midpoint between the sternal xiphoid process and the indifferent electrode along the right midclavicular line. Electrode 2 (CH2) was set at the midpoint between the sternal xiphoid process and the indifferent electrode along the left midclavicular line. Electrode 3 (CH3) was set at the lower 1/2 of the segment between the indifferent electrode and the umbilicus along the right midclavicular line. Electrode 4 (CH4) was set at the lower 1/2 of the segment between the indifferent electrode and the umbilicus along the left midclavicular line.