Abstract:The PINV has been widely applied to psychiatric investigations in which the definition of its abnormality depended on the visual evaluation without giving attention to its wave form. We have developed a new method of evaluating the PINV by applying the exponential regression correlation to raw and smoothed PINVs for the amplitude of the 15 points at the intervals of 70 msec. The significant correlation between the PINV wave form and the exponential curve was observed both in the raw and smoothed PINVs. Coefficient A was positively correlated with the PINV duration quantified by a visual measurement. Coefficients A and B had the negative and positive correlation with the CNV magnitude. The, findings obtained in 28 healthy subjects suggest that the PINV may correlate to the CNV magnitude.