Maturation of cortical potentials evoked by tibial-nerve stimulation in newborns, infants and children aged four and eight years.

This study traced changes in cortical activity (SsCEP) evoked by electrical stimulation of leg nerves during the period of fast morphological and functional development of the nervous system from birth to eight years of age. The study revealed complex waveform changes in the SsCEP during this period. At birth low-amplitude potentials with well-defined, simple, three-phasic waveform (P1, N2P2N3, P3) were present in only eight of 26 newborns: no SsCEP could be detected in 13 cases. At one year the SsCEP had a higher amplitude and the simple three-phasic waveform was seen in the majority of cases (15 of 22). At four years an SsCEP with a notch in the middle negative wave was the most common waveform, observed in nine of 18 cases. At eight years adult-like SsCEPs prevailed in the records: they showed well-defined peaks P1 (corresponding to P40 of adults), N2, P2 and N3 (probably corresponding to N75 of adults). Such waveforms were observed in 16 of 24 children. In newborns P1 had a latency of 37 . 5 +/- 2 . 54ms: at one year the latency decreased to 32 +/- 3 . 81ms and increased again in older children, corresponding to increasing body-length.