Abstract: Objective　To study the variation of latency and amplitude of the event related potential （ERP） and its distribution in human scalp when the normal subjects were stimulated with different visual fields. Methods　The ERP recorded in scalp with the stimulation of 10° visual field and 60° visual field respectively in 20 healthy volunteers with normal visual function. Results Two different visual field stimulation may evoke the different exogenous components P1（70-125 ms）, N1（90-170 ms）, P2（140-220 ms） and endogenous components N2（190-280 ms） and P3（290-430 ms）. The latencies of all the components evoked by 10° visual field were shorter than that of the 60° visual field while the amplitudes of N1 and N2 were lower and appeared over the extensive encephalic region; and the amplitudes of the P1, P2 and P3 were higher and appeared in occipitotemporal, prefrontal and occipital region, respectively. Conclusion Two different visual field stimulation may evoke all the ERP components with significant differences in the latency, amplitude and distribution. The differences may reflect the different visual information integration and processing in human brain during the different visual field stimulation.

Key words: forensic medicine, evoked potentials, visual fields