Developmental change of short latency somatosensory evoked potential waves between P3 and N1 components in children

We attempted to isolate and identify the negative waves between the conventional P3 and N1 components of short latency somatosensory evoked potentials (S-SEPs) in children. Twenty normal children ranging in age from 3 months to 12 years, and 11 adolescents and adults were studied. The median nerve was stimulated and recordings from F (F3 or F4) and C' (1-2 cm posterior to C3 or C4) contralateral to the stimulation site were simultaneously obtained in order to identify each negative wave in the C' recording. The wave of C' coincident with that of F was regarded as the far-field potential, and the wave of C' that diverged from F as the near-field potential at the scalp. There were one negative wave (N1) in the far-field potential and 2 negative waves (N2 and N1(3)) in the near-field potential, after the P3 component. "N1(3)" was conventional N1 and "N2" was the negative wave just before N1(3). In infants and younger children, the interpeak latencies of P3-N1(3) and P3-N2 were markedly elongated in comparison with that in older children. These interpeak latencies may be useful as an index of cerebral maturation.