Characteristics of auditory P300 in children: application of single trial analysis.
As, especially in children, cognitive function might vary from one stimulus to the other, even when the same target stimuli are presented in the oddball paradigm, we applied the single trial analysis adopting discrete Fourier transformation followed by inverse discrete Fourier transformation to the auditory P300 for the first time in children. In 9 children, age 9-13 years, a positive peak was clearly identified in approximately a quarter of the processed single sweep responses to target stimuli (single sweep P300), whereas it was observed less frequently for non-target stimuli. In 2 children of age 6 years, it was difficult to discriminate single sweep P300 from background EEG activities even in the processed data. As for the former group, the detection ratio of P300 in single sweep target responses ranged from 10.0 to 40.0%, and its mean latency and amplitude ranged from 311 to 348 ms and from 31.7 to 41.5 microV, respectively. There was a significant correlation between average data and single sweep data in terms of the P300 latency. However, the amplitude of P300 in the average data bore no relation to the detection ratio, mean amplitude or variability of latency among single sweep P300s. As compared with adult data previously reported, the detection ratio of single sweep P300 was lower and the P300 amplitude was higher in childhood. P300 in children, at least past puberty, can be analyzed by using the single trial method, which is expected to provide more information about the development of human higher brain functions, especially cognitive function.