Abstract: Objective To explore the change of brain cognition function in severe head injury and the correlation between P300 in event-related potential(ERP) and intelligence quotient(IQ) .Methods Auditory P300 was measured and intelligence quotient was tested by Wechsler Adult Intelligence Scale Revised in China(WAIS-RC) in 40 severe head injury patients.Auditory P300 was measured in 40 normal healthy people as control group.Results The latencies of P300 in severe head injury patients group were longer than in control group.There was a significant difference between the two groups(P<0.01) .There were significant negative correlations between P300 latency and VIQ and FIQ respectively(r=-0.335,-0.344,P<0.05) .Conclusion ERP might be taken as an objective index for measuring the change of the brain cognition function in patients with severe head injury.

Key words: event-related potential, ERP, P300, intelligence quotient, severe head injury