Maturation of Cyclopean Visual Evoked Potential Phase in Preterm and Full-Term Infants

PURPOSE. P1 is the major positive component of pattern-reversal visual evoked potentials (PR-VEPs). The rapid decrease of its latency correlates with the progressive myelination in the developing infant brain, which affects signal transmission in the visual system. An age-dependent phase shift, analogous to P1 peak latency, can be observed in dynamic random dot correlogram (DRDC)-evoked VEPs (DRDC-VEPs), a method used to assess binocular function. Our goal was to study the relationship between cyclopean DRDC-VEP phases and PR-VEP P1 latencies in full-term and preterm infants so as to further explore the experience dependence of early binocular developmental processes. METHODS. DRDC-VEPs and PR-VEPs were recorded in 128 full-term and 47 preterm healthy infants and toddlers. DRDC stimuli were presented on the red and green channels of a CRT monitor while infants wore red-green goggles for dichoptic viewing. Reliability of VEP responses was assessed by the T(circ)(2)statistic. Logistic function was fit to the phase and latency data as a function of age, and goodness of fit was assessed by analysis of residuals. RESULTS. The phase shift of DRDC-VEPs and the rapid decrease of P1 latencies occur at identical postconceptual ages. A correlation also was found between P1 latencies and DRDC-VEP phases. CONCLUSIONS. Although development of binocularity is an extremely experience-dependent process, our data suggest that DRDC-VEP phase and P1 latency mature independently from visual experience. We propose that both the phase shift and decreasing P1 latency are indicators of myelination and increasingly faster signal transmission in the developing visual system.