Maturation of the visual evoked response in newborn miniature pigs

As a prelude to neurobehavioral toxicologic studies in neonatal minipigs, normal maturational changes in the visual evoked response (VER) were determined in 6 Hormel-bred minipigs. The VER were highly variable for the 1st several days of life, but were reasonably stable by the 2nd weeks. All adult waveform components were present at birth, and maturational changes primarily affected waveform latency and consistency. Only one waveform (Pi) was sufficiently distinct and consistent for statistical evaluation. At birth the latency to Pi was about 102 ms. The latency of Pi rapidly decreased to about 56 ms during the next 25 days, and subsequent changes were minimal. Comparison with other species indicates many cross-species relationships of specific VER components, with the minipig VER having many maturational and topographic similarities to the human VER.