The waveform of the group mean SEP of normal human subjects

The following conclusions were deduced from 200 SEPs recorded from 100 male and 100 female controls, of average age 22.34 +/- 1.70 years. (1) It was confirmed that the waveforms of a group mean SEP and of a group SD converge to a waveform which is not a flat horizontal line. (2) The waveform of the group mean SEP for the 200 normal subjects consisted of 12 components and was tetraphasic within 500 msec latency. The waveform of the group SD for the 200 normal subjects was also shown. (3) Some coincidences were established in early components within 50 msec latency, between the group mean SEP obtained in the present study and the group schematic SEPs reported by others, but large discrepancies were noted in later components. (4) With scaled SEPs, which were converted from unscaled SEPs by amplitude scaling in order to eliminate individual variation in absolute amplitude, similar results were obtained to those with unscaled SEPs. These results indicate the possibility of data reduction by amplitude scaling.