Interpeak components of event-related potentials--comparison between normal and schizophrenic groups]

Event-related potentials (ERPs) during a two-tone discrimination task were recorded in 85 normal subjects and 110 schizophrenic subjects. We divided ERPs into 4 interpeak components. We named them A, A', B and B'. A is the component from the stimulus point to n100 peak. A' is the one from n100 peak to p200 peak. B is the one from p200 peak to n200 peak. B' is the one from n200 peak to p300 peak. Their latency was named Al, A'l, Bl, and B'l respectively. Their amplitude was also named Aa, A'a, Ba and B'a respectively. Bl and A'l of the schizophrenic group were both significantly longer than those of the normal group. B'a of the schizophrenic group was significantly smaller than that of the normal group. Interrelations between interpeak components of the normal group were examined statistically. Regarding latency, a significant negative correlation was seen between Al and A'l, and also between Bl and B'l. Regarding amplitude, a significant positive one was seen between Aa and A'a, and also between Ba and B'a. Interrelations between Al and A'l, Bl and B'l, Aa and A'a, and Ba and B'a of the schizophrenic group were the same as those of the normal group. These negative correlations in latency suggest that n100 peaks and n200 peaks have 'jitter'. A combination of interpeak components is supposed to reflect a higher function of the brain. There was a significant negative correlation between (A + A')l and (B + B')l in the normal group, but there was not a significant one between them in the schizophrenic group. The schizophrenic group is supposed to have a certain abnormality in a higher function of the brain. Our result suggests that we may possibly be able to associate an abnormal focus around p200 peak with some symptoms and signs of schizophrenia.