The purpose of this study was to investigate the maturation characteristics of neonates.

Ninety three neonates underwent a somatosensory evoked potentials(SEPs) testing. Twenty four point seven percent of them were neonates at risks including the neonatal asphyxia, low birth weight under 1500 g, or a suspicious CNS abnormality.

Seventy five point three percent of neonates showed normal median SEPs, and 24.7% of them showed abnormal or a flat response. The mean latency of the first cortical component(N1) was 25.3⁑5.4 msec, duration 16.3⁑5.5 msec and amplitude 1.00⁑1.27 ㄍV.

Thirty one point two percent of neonates showed normal posterior tibial SEPs, and 68.8% showed abnormal or a flat response. The mean latency of the first cortical component(P1) was 44.9⁑5.6 msec, duration 17.5⁑3.9 msec and amplitude 0.47⁑0.38 ㄍV.

This result suggests that the maturation of rostal nervous system develops earlier than the caudal system.

Linear decrease of the cortical latency with post-menstrual age reflects maturation of the central pathway and not merely maturation of the peripheral nerves. But our study showed much less frequency of recordings of the tibial nerve SEPs than the median nerve responses, which suggested that the maturation of spinal cord and lower-limb nerves would be slow, in addition to that the length of pathway was increasing. This result suggests that the maturation of the proximal shorter nervous pathway develops earlier than the distal longer pathway.