- A A Aleksandrov: Department of Higher Nervous Activity and Psychophysiology, Faculty of Biology and Agriculture, St. Petersburg State University, 7/9 Universitetskaya Bank, 199034 St. Petersburg, Russia.
Experiments were performed to measure the critical duration of acoustic stimuli at which the generation of mismatch negativity is still possible in auditory evoked potentials in the human brain, arising in conditions of presentation of standard and deviant stimuli differing in terms of frequency (1000 and 1200 Hz respectively). Studies were performed in two groups of adolescents (aged 11-14 years): 1) those with normal attention characteristics and 2) children with attention deficit. The results showed that normal children had the same critical duration for sound stimuli at which mismatch negativity could be generated as adults. Mismatch negativity still appeared at a stimulus duration of 50 msec, while the mechanism generating mismatch negativity did not operate at durations of 30 and 11 msec. In children with attention deficit, statistically significant mismatch negativity was not seen at all durations of short acoustic stimuli (11, 30, and 50 msec).