[Age and changes in the latent periods of the slow human auditory potential]

Regular changes in latencies of slow auditory evoked potentials were found with age. In particular, peak-latencies of comparatively early deflections, i.e. P1, N1 and P2, progressively diminished. The shortening of latencies was 50-60 ms for the age between 3-7, 8-13, and 25-35 msec further on. The latencies of the later waves, namely P3, N3 and P4, increased by 35-65 ms for the age between 3-7 and 8-13. After these ages, the latency of deflection P3 did not change, while deflections N3 and P4 disappeared. Of all the evoked potential components deflection N2 was the most stable, its latency negligibly shortened with age. In children aged 3-7 two complexes of waves (P1N1P2 and P2N2P3) often overlapped, forming a broad nondifferentiated deflection. The division of the latter was completed at the age of about 8. Long-term developmental changes in wave-shape and parameters of the slow evoked potentials are considered as supporting their mainly nonspecific (extralemniscal) orgin. Basing on correlation revealed between the late evoked potential components and EEG synchronization level, a hypothesis is advanced according to which these components are generated with participation of the nonspecific synchronizing system.